Monday, December 10, 2012

Winter Will Come

Hi, here it is December 12th and no snow. Today was another abnormally warm day. But the temperatures will cool back closer to normal the rest of the week. I can already hear the comments on this blog saying this winter is just like last year and is hereby canceled. Last year the AO was north all winter, that's about as rare as it gets. Things are starting out warm. But if you read my winter outlook and my Facebook fan page, this warm start to winter 2012-2013 was expected. The first part of December was very warm, 7-10 degrees above normal. But, this will not be the case for much longer and signs are already showing up for more of a cold pattern. We need the low over the Gulf of Alaska (GOA) to be replaced by an Aleutian Low. This will allow a positive PNA pattern with a ridge to the west and trough in the East. With this fix we can get our cold air to come down and visit the Eastern US.

The Teleconnections:

The ENSO is now neutral and should stay there for the remainder of the winter of 2012-2013.

The AO:

The NAO:

The PNA:
There are signs that the low over the GOA is going to breakdown. The current negative Western Pacific Osculation has been going strong for the last few months. it is gone or almost gone. which has been dominant for a couple of months. Because it is gone and forecast to remain gone. This should allow ridging south of Alaska to shift towards the Aleutians, and pump very cold air into Alaska and western Canada. The PNA is super negative at this time. With the negative WPO over, we should see ridging south of Alaska to shift towards the Aleutians, and pump very cold air into Alaska and western Canada.

The EPO is positive right now. The GFS whats to head the EPO back into negative territory. However the EURO is not showing this to any great degree. I think the Euro has a better handle on the EPO, at this time. The Euro is showing a trough for the East and West Coast; this will imply cold air in the east. Based on this I feel the very warm temperatures we've seen in the first part of December are just about history. The air that will be coming in for the 2nd half of the month won't be super cold. But it will be cold enough for snow. It does look like ridging will try to develop northeast of the region. That would favor interior northeast and Northern New England. It looks like the 2nd half of December will be more stormy than the first half; this will be key if we want snow.  

The Euro long range:

The ECMWF (Euro) model long range forecast for the three months of January, February and March is showing that the temps will be near normal for the Northeast. It is also showing that the winter time precipitation will be above normal. Due to licensing issues I can't show the model runs but I can show you this.  
The model is trending toward more in the way of a stormy weather pattern for the Ohio Valley and here in the Northeast for January through March.  One thing that did surprise me was the model is forecasting colder temps for the Great Lakes; if this does verify it would start the lake machine cranking up in a big way, given that the lakes are a few degrees above normal for this time of year.  As always, this is just one of the models and we're looking out three months. But the Euro has a better track record than the other models when it comes to long range forecasting.    
If you what to subscribe to model runs here are a few good sites.  
The models:  
First of all models are not perfect. So a good forecaster only uses them for guidance. If you've been following what I'm saying on blog post and on my Facebook fan page, then you know I said December was not going to be exciting until the second half. The models are showing increased chances for both cold and snowier weather for the Northeast.  
Over the weekend the northern Plains got hammered with a Blizzard. As much as 18 inches of snow fell in parts of Minnesota and Wisconsin. What does this mean for us here in the Northeast, well nothing really. But when the Mid West gets snowstorms in December; the East Coast usually has a good end of December thru February, snowfall wise. why is this? A snowpack in Lower Canada and the Western US allows for the Arctic air to have more staying power. The GFS Ensemble for the 16th of December is showing colder air going into Christmas week.

Christmas week:  After a few snow showers and flurries tomorrow morning. We should see 4 or 5 days of cooler but dry weather. The next storm system will likely move through Saturday night and Sunday with a chance of some rain.
The models overnight have moved towards a solution and are showing two potential significant events. The first one is the low pressure area for December 15th, which looks like it's going to track up through the Northern Plains.  The Second and potentially bigger event would be the first major winter storm the season on or around December 18. With the low pressure area tracking up from Arkansas through Tennessee Eastern Kentucky Eastern Ohio West Virginia and up into the Northeast. The Euro has had it for several runs. The 18 Z GFS is showing activity that could bring snow into the Northeast. I think the Euro is overdoing it a bit, but it's still a possibility.  I feel the Euro will shift toward the GFS. The GFS might come a little more to the west for the 18ht. I do think there is a good chance for a mid-Atlantic/Northeast winter storm early next week.  
The GFS showing the 17th.

gfs_namer_156_1000_500_thickfor the 17th

Winter time precipitation looks to be above average for January, February and March . But remember, This is going to be ENSO neutral, neutral years tend to be see saws as far as temperatures go, with swings between warm outbreaks and cold outbreaks. And since cold air is needed for snow, snow storms would depend on cold air. I can't guarantee which storms will be snowstorms. But if the Euro is right and the next three months in the northeast will be colder and wetter on average. Then I feel it's safe to say snow should end up above average for the winter of 2012-2013. So don't abandon the ship just yet....winter will come.    


Thursday, December 6, 2012

Looking At The Pattern for Mid December.

Many are wondering where is the winter weather, and will this winter be a repeat of 2011-2012. As for where is winter, The real cold air has been locked up across the interior of Alaska and northwest Canada since the middle of November. Parts of Alaska have had  -50 degree temps for over a week, with yesterday being the coldest day yet, –56. As for will this be a repeat of last year? The Short answer is NO. If you’ve read my 2012-2013 winter outlook; you know, I said the first third to half of this winter season would be warmer than average, with the second part of winter coming in colder than average. I still feel this will be the case. Here is a link to the winter outlook. The pattern over the next week or so,will be very unfavorable for sustained periods of cold and snow along the East Coast. But This will change.

As I said, the cold air is bottled up in Alaska and Canada. Why is this happening? The negative PNA and Positive NAO has high pressure high pressure to our south forcing warm air to move in from the southwest. What is the reason for this. The giant vortex up in Alaska is the reason it's been so warm here in the Northeast. This vortex will start to break down soon. I will once again go to the teleconnections, to show you how all of this should workout.  

The Teleconnections:  

I will be going into four indices, three of them I've talked about quite a few times in the past. However, there is one that I have not...I will talk about that after go into the NAO,AO, and the PNA.

   The NAO:

As you can see on the chart the NAO is currently sitting around neutral. If you follow my post on this blog and fan page, then you know, that when the NAO is positive our weather in the Northeast is generally warmer and drier. This is because of the lack of any real block slowing the storms. Looking ahead especially around the 10th-16th and on, the forecast shows the NAO going strongly negative. When this happens we will see a trough develop and the colder air to our north coming down to visit.

The AO:

In order to get real cold air out of Canada, the NAO needs a helping hand. This is where the AO comes in. When the AO is negative it allows the cold air in Canada to drop south into the United States. Now some of you may be wondering the AO is negative. If you look at the AO forecast chart you will see the AO has been negative since the 20th of November; So why is the cold air still locked up in Canada. To answer that we will have to look at two other indexes. The first I've mentioned before, that one is the PNA. However there is one other that I haven't talked about before, that one is the EPO, both of these are playing a role as well.

The PNA:

The PNA does the same thing for the West Coast, that the NAO does for the East Coast. By this I mean, when it's positive the West Coast is warmer and drier; when it negative the exact opposite is true. If you look at the PNA forecast chart, you will see that it has been weakly negative. So the west has been cold....but the cold can't push farther east. just as the NAO being positive has prevented the negative AO from supplying us with colder air. Looking at the PNA forecast chart again, you can see the PNA looks to stay negative going into mid month. The forecast had been calling for it to be neutral to positive, this is a fly in the ointment. So it will have to be watched to see if it trends back more to the positive side. But, the PNA has a variable effect on the East Coast, I will have more on that in a bit. Looking at the NAO and AO forecast charts you can see they will be in a negative phase. Even with a negative PNA I still think we will see colder air infiltrate the Northeast after mid month. How do I know this? For that we have to look at another teleconnection, the EPO.

The EPO:

12zecmwfensepoeuroEPO Now while the PNA has an impact on northeastern pressure patterns, as I said it is variable. But, the EPO whether directly or indirectly has even more influence over the East Coast and the GOM.

The EPO (Eastern Pacific Oscillation). The EPO is, at its simplest, the alternating pattern of high and low atmospheric pressure, located four to seven miles above the Pacific Ocean. The EPO helps determine the pattern of the jet stream moving from the Pacific across North America. This means it's what controls troughs and ridges around Alaska; when it's negative, a trough will be in place near Alaska. So a positive EPO will produce a ridge in the same place. If you look at the EPO forecast chart, you will see that by mid month the EPO looks to be positive.

OK, why the warm weather?

I'm sure all of this negative / positive teleconnection talk is giving some of you a headache. So I will try to explain it another way. Most of us know that generally in the northern hemisphere weather systems moves from west to east. So in order see what the weather will be like down the road here on the East Coast, one has to look to the west. Since the EPO is influencing the weather in the Pacific Northwest, we must look there first.   

OK since the EPO is negative, we see a trough over Alaska and a ridge off the West Coast. This trough in the west lends support for a ridge in the east. Now since the AO will send the cold where the trough is, which in this case is out west. Add in the positive NAO and ta-dah, we have warm weather in the Northeast.

So it makes sense that when the EPO goes positive along with the negative NAO and AO that's being forecast around mid month, that this all points to colder air moving into the eastern part of the United States. The negative NAO should create a Greenland block which will in-turn force coastal storms to form and move into the northern Mid Atlantic and Northeast. How much staying power the block has will depend on the vortex over the Atlantic. ... But all and all, the way the indices are trending is a very good thing if you're a snow lover.

The GFS showing the 17th of December  .


  A look at the GFS 12Z model run showing the 20th.


And here is the GFS showing the 21st.

If you look at the model runs above, you can see the results of what I was talking about. The EPO is no longer negative. and with the high pressure that's been hanging off the East Coast moving out of the way, cold air is moving into the Northeast. The pattern still looks to become more active than we've seen the last 10 days. The NAO does look to become east based. So if we get any storms this will help steer them our way. As I said in my winter outlook, this winter will be a roller coaster as far as cold and warm air outbreaks. As you can see, the GFS does show a lot of cold air in place just before Christmas. The models also show we have a good chance for a storm around that same timeframe. With the Greenland blocking to the north, the storms after mid month will finally have the cold air to play with.    But the bottom line is, we should have plenty of chances for minor to moderate snow events after the 10th of December.

When I looked at past snowy Decembers, many of them had the same general pattern. We are looking fairly far out for any kind of real forecast. But, I feel our chances are good in seeing more in the way of snow in 10 to 14 days.   

Well that’s it for now, I will have more on all this as we go on…just check back here or follow the sidebar gadget to my Facebook fan page.     


Monday, December 3, 2012

Where is the winter?

Ok here is quick post on the change I've been talking about mid month. The timeframe from the 9th to around the 20th of December will see cold arctic air moving south. We will also see more in the way of storminess.

Where is the cold air?

Right now it’s bottled up in Alaska.

  The reason we haven't had any real arctic air in the Northeast is the current orientation of the polar vortex. For those who don't know, in the northern hemisphere, the polar vortex is a large cold core low pressure area located near the North Pole. The polar vortex is analyzed at the 500 millibar level of the atmosphere. The polar vortex can often be located over Canada since the coldest surface air is often found over high latitude icy/land locations. It normally gets stronger during the winter and weaker during the summer.


On this polar chart you can see the PV has been displaced a bit over Siberia. The trough over Eastern Asia and the Bering Sea should help this process along. If they split the PV, we would have a good chance of seeing an arctic outbreak from mid month thru the end of the month. This would collate with the teleconnections I've been talking about.

The NAO, PNA, and the AO.

Over the last week, I've been talking about the PNA and the NAO.  



PNA will be in a positive phase from mid month on.



NAO will be in a negative at the same time.

 The AO


As I said on my weather page the other day; you want a positive PNA and a negative NAO for cold air to infiltrate the Northeast.

The AO will also be in a negative phase. this will give the cold air a chance to dig into the Mid Atlantic and maybe as far south as the Carolinas by mid to late month. With the NAO and AO both negative we should have a Greenland block setup.....this would be good news for snow lovers if the storm track workout.


anomnight_current sst As you can see convection has returned to the mid Pacific tropical zone (around the dateline). Last year, there wasn't a lot of convection in this area. Things will start to change in the Gulf of Alaska . The convection across the dateline extending to the NW will have a part to play on the setup around the Gulf of Alaska.

This ridging is what is going to help displace the vortex near the Gulf of Alaska . This will allow the cold air to move south. These changes will induce stormy weather into the Midwest and East Coast. During this timeframe we should see the lake effect machine also wake up in earnest .  

The convection across the dateline extending to the NW This is what is going to help displace the vortex near the Gulf of Alaska , along with increasing the number of storms move out of the Pacific Northwest. All of this is expected between the Dec 12-17th. which is supporting the change around mid month I've been talking about.  

The 9th and 10th of December.

The Euro showing the 10th of Dec.


 The GFS for the 10th of Dec.


  As you can see the pattern will start to get active around the 9th or 10th.  Right now, We could end up dealing with a severe weather threat in parts of the Tennessee and Ohio river valleys on Dec 9th. This severe threat would move to the east on the 10th. On the GFS you can see the arctic air moving into the Plains….This would end up being a nice snowstorm for the Quad Cities into the northern great lakes. As the cold works it’s way east, so would the snow…

That’s about it, I will have more about this as the time approaches.


Monday, November 19, 2012

Are We Returning To The Weather Patterns Of Past Decades, Part one

Hi it's Rebecca here, we've been hearing terms like unprecedented in describing the weather over the last 3 years. But is it really unprecedented?  I thought I would do a post that covers this. Due to the length of the subject I will most likely break it down into three or four parts. Part one will deal with the hurricanes seasons of 1954,1955, and 1960. It will try to show you, what we've been seeing is nothing truely execptional; when it comes to tropical activity in the Atlantic Basin.

Right after Super storm Sandy stuck, back in the end of October, former Vice President and global warming advocate Al Gore was making the news circuit on TV. Al Gore was claiming that global warming was to blame for Hurricane Sandy’s wrath. Gore said, “The storms are getting stronger. The stronger storms are getting more frequent. And you know, this is the second time in two years that part of Manhattan has been shut down … But the evidence is now so overwhelming.”

In an interview on Fox News a few days later. Joe Bastardi, chief meteorologist at WeatherBell Analytics called Gore’s claims “stunningly ignorant or stunningly deceptive.” According to Bastardi, such storms are nothing new, “In the 1950s 10 major hurricanes ran the eastern seaboard. Six hit the Carolinas northward in two years.” Bastardi also said, referring to Al Gore "He doesn’t know what he’s talking about. And ever since he shot his mouth off about Katrina, we’ve seen total global tropical activity go to record low levels. Just because something happens in your backyard two years in a row, it has nothing to do with the total picture"

In 2006 Bastardi showed evidence that hurricane activity was going to look like the 1950's. He based this on teleconnections patterns. He showed evidence that the cycle of a colder Pacific and warmer Atlantic, leads to increased tropical cyclone activity. When we were in the 50's we had a warm PDO and AMO; but then the PDO switched to the cool side. This lead to warm dry summers and huge droughts.

I'm not a follower of Joe Bastardi in anyway. I've disagreed with him in several areas. But in this I feel his evidence is sound.

If you've follow me on this blog or on my Facebook weather page; you know I'm a big believer in concentric patterns, be it weather or other things in nature and across the universe. With this in mind, research done by the National Center for Atmospheric Research (NCAR) reveals just such a thing when it comes to hurricane activity For the Atlantic and Caribbean NCAR has found a 20-30 year cycle for hurricane frequency The last intense period was in the 1950's and 1960's with a lag between 1970 and 1994. We've been seeing an uptick in the number of Atlantic hurricanes over the last few years. Since the number of hurricanes is increasing, so are the chances for landfall everywhere along the east coast of the U.S.

One term I want you to know is a Cape Verde-type hurricane. This type of hurricane is one that that develops into a tropical storm within 600 miles of the Cape Verde Islands and then becomes a hurricane before reaching the Caribbean.

Looking Back:

Looking back at hurricane activity for the last 160 years. The 1850s to the mid-1860s was fairly inactive, the late 1860s through the 1890s were busy and the first decade of the 1900s were quiescent. The mid 1930s through the 60's were active. We saw low activity 1970-1994, Since the mid 90's hurricane activity has started to become active again.

  The last intense period of hurricane activity was the 1950's into the 60's. Besides meteorology one of my other passions is history. History is many things, but mainly it's a study of what people were thinking and why they thought that way. There's two things that never cease to amaze me about people; the first being how they think things have never been as bad as they are right now. The second is how human societies can sweep anything under the proverbial rug.

The last 50 years on average have been quiet landfalling hurricane wise. Because of the way people think; we've seen a lot of development along the coastline. So even though we can forecast hurricanes more accurately, we are more vulnerable than ever to landfalling tropical cyclones.  

A few of the greatest hurricanes ever recorded in the Atlantic Basin: 

The deadliest natural disaster to ever strike the United States was the Galveston Hurricane. In 1900 this hurricane resulted in an estimated 8,000 -12,000 direct fatalities when it made landfall in Galveston, Texas.      

The Labor Day Hurricane of 1935 was a category 5 hurricane on record to hit the United States. take which was overall a fairly quiet season by most standards with six named storms the entire year. Like Katrina, Rita, and Wilma in 2005, the Labor Day Hurricane underwent explosive growth in a very short time. Only a mere fledgling tropical cyclone entering the Labor Day Weekend in September, 1935, the Labor Day Hurricane rapidly intensified to the most intense hurricane on record at that time with a barometric pressure of 892 mb. Winds were as high as 200 mph.      

The death toll will never be completely known, I've seen 400-600 in many books. However, I know those figures to be wrong. World war 1 veterans and been working on a railroad bridge that was going to connect the Keys to the mainland. The storm was powerful enough to completely destroyed what had been constructed prior to the Labor Day Hurricane. In a telegraph sent to President Roosevelt on September 8, 1935 Colonel Ijams said "LOSS OF LIFE FROM SEPTEMBER 2, 1935 HURRICANE IN FLORIDA CAUSED BY TIDAL WAVE, STOP PROXIMATE 250 MPH WINDS STOP TENTATIVE DEAD AND MISSING 684 STOP WILL INVESTIGATE ..."    

In addition to the veterans, there were those who followed the work camps. As well as most of those from the Seminole tribe were not in any official census records. The bridge project has been dubbed The Bridge That Never Was.      

The Great New England Hurricane of 1938 (Long Island Express) slammed into Long Island, N.Y., without warning as a category 3 storm. It had been nearly a century since New England had been pummeled by a major hurricane, and many did not see the storm coming. At least 700 people were killed, while 9,000 homes and buildings were destroyed. The storm was so powerful, it created 12 new inlets on Long Island.    

The 1950's were very active. If you take a look back, you will find names like Carol, Connie, Diane, Donna, Edna, Hazel.

Before I get started there's one thing I want to bring to your attention. The first US named hurricane (unofficially named) was George, which hit in 1947. They started naming them more or less officially in 1950. Also from 1953 through 1979, only women's names were used, often the same names were used year after year when things were getting started. The National Hurricane Center started using mixed gender names in 1979.        

The 1950 Atlantic hurricane season was a active season with sixteen tropical storms, with eleven of them developing into hurricanes. Eight of these hurricanes were intense enough to be classified as major hurricanes (On the Saffir-Simpson scale a category 3 with wind of 111 mph or greater). The high number of major hurricanes make 1950 the record holder for the most tropical cyclones of such intensity in a single season.        

 In the years1954-1955 there were a total of six hurricanes that affected the Carolinas, the Mid Atlantic and New England.        

1954 Hurricane Season:      

The 1954 hurricane season was unusual in several ways. In total, there were 11 tropical storms, 8 hurricanes, and 3 major hurricanes ( There could have been one more major hurricane. Dolly never made landfall. But, her winds were estimated to have been 100 -115 mph by airplane. Of those 11 tropical cyclones, five of them had an impact on the United States. Two of the tropical systems Alice and Barbara had an effect on Texas. The other three had a landfall on the East Coast. Having almost half of the Atlantic Basin tropical cyclones impacting the U.S. is nothing short of extraordinary

Another unusual feature in 1954 was the absence of tropical cyclones in Florida, Georgia, and the east Gulf States and the passage of three hurricanes through the North Atlantic States and New England.

One other curious fact is none of the 1954 tropical cyclones formed in the western Atlantic; in fact, all were charted west of longitude 65" W, with the exception of Hazel which had its origin between 55' and 65' W. Three of the major hurricanes, Carol, Edna, and Dolly developed only a short distance east of the Bahamas, while Hazel, also a major hurricane, formed in the eastern Caribbean. Of these four, Carol, Edna, and Hazel went on to played mayhem from the Carolinas into New York and New England. All of this in only a 7-weeks, August 30 to October 15 period.      


She formed near the Bahamas on August 25th. On the 27th, when the hurricane was moving east of North Carolina land stations reported category 1 and 2 winds of 90 to 100 mph , with tropical force winds at Cherry Point North Carolina. Carol passed just east of Cape Hatteras with winds between 75 mph to 125 mph. She intensified further as it accelerated northward, striking eastern Long Island as a strong Category 2 or perhaps a Category 3 hurricane. She made her final landfall on Old Saybrook Connecticut late in the day on the 31st. Within a few hours, the hurricane became extra-tropical over New Hampshire, later dissipating over Quebec.      

Across New England , Carol caused a surge in Narragansett Bay that reached 14.4 ft. The hurricane destroyed about 4,000 homes, 3,500 cars, and 3,000 boats. Damage totaled $460 million (1954 dollars), and there were 60 deaths


 Hurricane Edna came close on the heels of Carol, forming east of the Lesser Antilles on September 2. She was moving northward and passed just east of Cape Hatteras early in the night of the 10th and winds of 75 mph. Soon after, Edna started her turn to the very north northeast closely paralleling Carol's path just 11 days earlier. She moved rapidly northeastward, after becoming a major hurricane she pasted very close to Cape Cod on September 11th. Later that night she made landfall in eastern Maine, Nova Scotia, and New Brunswick. Edna accounted for 20 casualties, mostly from people drowning, and over $42 million (1954 dollars) in damage, mainly from the Long Island area northward across New England. Brookhaven National Laboratory in Long Island measured 95 mph winds.      


Hazel came along a month later. She was an extraordinary hurricane for an amazing hurricane season. Hazel formed on October 5 just east of the Windward Islands and intensified into a major hurricane on her way across the Caribbean, winds were 115 mph. on the 7th and 125 mph. on the 8th, as estimated by reconnaissance aircraft.      

After killing as many as 1,000 people in Haiti, Hazel set her sights on the United States. Storm warnings were hoisted at 1100 EST on October 14th from Charleston, S. C., northward to the Virginia Capes, and the remainder of the coast northward to New England was placed on the alert by Washington and Boston Weather Bureau offices (the forerunner of the National Weather Service).      

She made landfall on October 15th near the border between North and South Carolina as a Category 4 hurricane. Moving at extreme speed on a north-northwest track, sometimes at 60 mph. In 12 hours she passed through the western suburbs of Washington, D. C., and spun across Pennsylvania and New York where she merged with an existing powerful cold front. Before moving into Ontario and stalling over the Greater Toronto Area. During this time span Hazel mostly maintained her intensity. Peak wind speeds of 90 mph. or over were reached near and east of the center from the Carolinas through New York. She impacted several states, including Delaware, Maryland, New Jersey, New York, Pennsylvania, Virginia, and West Virginia. It would be 6 years before another hurricane would affect even more eastern seaboard states.    

Hazel resulted in 20 deaths on the Carolina beaches and about $163 million (1954 dollars) in damage to the Carolina beaches and the interior of North Carolina. The death toll for the area along the hurricane's path north of the Carolinas into the Canadian provinces of Quebec and Ontario was about 149 with 78 to 81 of the total in Canada.      

Even though the Atlantic hurricane season is from June 1st and ends November 30th. The 1954 season wasn't done. The final storm of the season, Alice, developed on December 30 from a trough of low pressure in the central Atlantic Ocean in an area of unusually favorable conditions. The storm moved southwestward and gradually strengthened to reach hurricane status. It persisted into the following calendar year, passing through the Leeward Islands on January 2. Alice reached peak winds of 80 mph  before encountering cold air and turning to the southeast. It dissipated on January 6 over the Caribbean Sea.

Here is a video that shows the tropical cyclone tracks in 1954. 


1955 Hurricane Season:        

There were 13 tropical cyclones in 1955, of which 10 attained hurricane force, Three of the storms stuck the East Coast.        


Hurricane Connie was the first of three hurricanes that hit North Carolina in 1955. It hit as a Category 3 hurricane, having weakened from a Category 4 hurricane. Hurricane Connie caused one of the most disastrous and costly floods of record in the northeastern States. The hurricane's slow movement on the l0th, l1th, and 12th resulted in heavy rainfall from North Carolina northward across the northeastern States to the interior of New England. The rains did not let up until the dying remnants of the hurricane had moved into the Great Lakes region on the 14th. The rainfall amounted to 2 to 8 inches in eastern North Carolina and ranged upward to 10 to 12 inches from the Chesapeake Bay area to extreme southern New York, damage in the United States was $40 million (1955 dollars). On August 14 Connie dissipated over the eastern Great Lakes.



Hurricane Diane was the second of three hurricanes that hit North Carolina this season. It hit as a minimal hurricane. The storm turned northward across Virginia, then it turned northeastward and moved back into the Atlantic near Long Island, New York on August 19. The sections worst hit were Pennsylvania, Massachusetts, Rhode Island, Connecticut, and southeastern New York, although there was some serious flooding from North Carolina northward. The sections worst hit were Pennsylvania, Massachusetts, Rhode Island, Connecticut, and southeastern New York; where significant flooding occurred. These same areas had received heavy rain from Hurricane Connie only five days before. The mountain streams quickly became raging torrents and began flooding the valleys within a few hours. The torrential rains broke all existing records in many places. At Windsor Locks, Conn., 12.05 inches fell between 10 a.m., August 18 and 9 a.m., August 19. The previous record at Hartford, extending back 90 years, showed a 24-hour maximum of only 6.2 inches. Damage has been estimated at $754,706,000 (1955 dollars)  of which $600,000,000 occurred in New England. These figures are admittedly incomplete and direct plus indirect damage would indicate that Diane earned the designation of "the first billion dollar hurricane." Approximately 200 persons lost their lives, all from Diane's floods.        


1one developed in an easterly wave which passed through the Cape Verdes on September 6 and the circulation was still quite weak on the 11th; but Ione began to develop on this date and reached hurricane intensity during the night of September 14-15. Ione then pursued a general northwesterly course toward the North Carolina coast. 'It reached greatest intensity on the 17th when a central pressure of 938 mb. was reported with maximum winds of 125 mph. By the time the hurricane reached the North Carolina coastline on the 19th, the central pressure had filled to about 960 mb and the maximum winds had decreased slightly. Ione was the third hurricane to pass through eastern North Carolina within six weeks and the fourth within eleven months. Ione damaged mostly crops in eastern North Carolina. The estimates were around 88 million (1955 dollars). Ione caused seven fatalities.        


Even though she made landfall in Mexico. I wanted to mention Hurricane Janet. She was another Cape Verde hurricane. She formed around the 11th of September. However, as a tropical cyclone, Janet wasn't officially discovered until it attained hurricane status on September 21. That's when, pilot reports from the airlines Air France and Iberia indicated the presence of a weak tropical disturbance at about Latitude 13.5' N. and Longitude 53.0' W. On September 25th a hurricane hunter aircraft reported conditions that showed rapid intensification was in process. At 0830 EST of the 26th, Lt. Comdr. Windham with a crew of eight and two newspapermen, on Hurricane Hunter mission Snowcloud, reported in at Latitude 15.4' N. and Longitude 78.2' W. that they were about to begin penetration of the main core of the storm. That was the last transmission from the plane, no trace of the aircraft or her crew were ever found. This is the only Hurricane Hunter mission lost in the Atlantic. Janet was the most powerful hurricane of the 1955 Atlantic hurricane season and is still one of the strongest Atlantic hurricanes on record. It made landfall as a Category 5 hurricane, causing catastrophic damage and at least 687 deaths in the Lesser Antilles, Yucatán Peninsula.

   Here is a video that shows the tropical cyclone tracks in 1955


1960 Hurricane Season:    

The 1960 Atlantic hurricane season wasn't very active. Only seven tropical cyclones formed in the Atlantic Basin. Four of these reached hurricane status. Two of the storms became major hurricanes. Donna became category 5, Ethel also briefly became a major hurricane, but rapidly weakened prior to landfall. You may find this interesting, of the seven tropical cyclones, five ended up impacting the United States. There may have been below-average activity, But Donna more than made up for it with her ferocity.        

The five systems that hit the U.S., were Tropical storm one which went into Texas, Tropical storm Brenda which went up the East Coast, Hurricane Donna, I will talk about her in a minute, Ethel which impacted the Gulf Coast, and Florence, she made landfall in Florida and drifted over the state for 24 hours, she then went into the Gulf where she made a turn, made another landfall on September 26th on the Alabama / Florida border.      


Hurricane Donna was a Cape Verde-type hurricane.

Hurricane Donna was the most destructive hurricane of the season. Donna produced hurricane-force winds in Florida, the Mid-Atlantic states, and New England.

On September 9th, Donna was over the Florida Keys with sustained winds reaching approximately 138 mph and gusts up to at least 178 mph (near the storm’s center). As a ridge of high pressure in the north began to decay around 10 September and the Westerly began to increase, Donna recurved and crossed the Florida Peninsula on 11 September. Despite its path over land, the storm remained intense and reorganized when it moved back into the Atlantic. In the Mid-Atlantic states, Elizabeth City, North Carolina reported 83 mph sustained winds, while Manteo, North Carolina reported a 120 mph gust. After moving back over the Atlantic; Donna accelerated as she move north northeast, She brushed Maryland, Delaware, and New Jersey. She crossed Long Island and then the New England region on 12 and 13 September (as a Category 3 system in Long Island, Category 1 or 2 everywhere else). In New England, Block Island, Rhode Island reported 95 mph sustained winds with gusts to 130 mph. Donna caused $400 million in damage (1960 dollars), and caused 364 deaths, of which 148 were directly caused by the storm.

There is evidence that she was acquiring extra-tropical characteristics by September 12th So she was most likely a hybrid system by the time she moved into the Northeast. This is most likely true of the Great New England Hurricane of 1938 as well.

Here is a video that shows the tropical cyclone tracks in 1960

As you can see, the active tropical seasons over the last few years is nothing new. In fact, as far as landfalling tropical cyclones it can be a lot worse then anything we've seen so far . Based on what I shown you,  there is no proof that Sandy was unique in anyway. Nor is the fact that a nor'easter inpacked the same area  a week later. None of the storms I've mentioned have ever been attributed to global warming in a way. So if these hurricanes weren't caused by global warming, how can we say the ones happening now are being caused by global warming....It makes no sense to me. How about you?

All of these great disasters were swept under the rug. Other events took over the  media spotlight and soon the memories of the American people. So Development along the coast continued.  It was the same for more recent hurricanes like Camille in 1969 and Andrew in 1992, they were overshadowed by other world events.  So we now find ourselves more vulnerable than ever.

Well that's it for part one.  Part two will deal with some of the reasons for these active seasons. It will also talk more about Hurricane Sandy.

Part two



The Monthy Weather Review, "Hurricanes of 1954"

The Monthy Weather Review, "Hurricanes of 1955"

The Monthy Weather Review, "The Hurricane Season of 1960"

Friday, November 16, 2012

The Leonid Meteor Shower

We will have perfect viewing weather for the Leonid meteor shower. We will have clear conditions for the first half of the overnight  and a thin crescent moon. After 4:00 or 4:30 we will have a weak front move out of Canada. The clouds associated with the front could be enough to interfere with the viewing.

This picture shows where the meteors will be coming from


The Leonid meteors are debris shed into space by the comet Tempel-Tuttle, which swings through the inner solar system at intervals of 33 years. With each visit the comet leaves behind a trail of dust in its wake. Much of the comet’s old dusty trails litter the mid-November part of Earth’s orbit and the Earth glides through this debris zone every year.  

Peak times to see the Leonids:   In the 2012 Observer’s Handbook of the Royal Astronomical Society of Canada, meteor experts Margaret Campbell-Brown and Peter Brown indicate that this year’s peak activity should occur on Saturday morning at about 3 a.m. ET. But while Leonid rates are unpredictable, it is unlikely that more than 10 to 20 meteors per hour may be seen this year.  

Tonight will be cold temps will be in the teens to upper 20’s, so bundle up. The best way to see them is to find a nice, dark place with no street lights and as few trees as possible, and look up. You may be happiest in a lawn chair wrapped inside a blanket or a sleeping bag. Hot coffee, tea or soup might be nice too.  

The meteors will moving quickly; most meteors streak by in a second or less. If you're lucky you might get to see a cluster of meteors. Because they are moving so fast, Leonid meteors tend to produce bright meteors, which leave long-lasting streaks or trains in their wake.

Here's a video of the 2009 Leonid meteor shower. video by Dave Kodama.


Tuesday, November 13, 2012

Will we see a coastal storm around Thanksgiving?

As yesterdays cold front continues to move off the New England Coast this morning, colder air will filter into the region. As you can see on these GFS runs, there are no real storms on the horizon for the next few days, in fact the dry quiet weather will stay in place for the next 6 to 7 days. Now while it will be dry, there won't be a big warm-up nether.

  GFS for tomorrow

  GFS for tomorrow


GFS for Thursday

              Friday GFS    

Friday’s GFS

SAturday GFS with

Saturday’s GFS, it’s still dry in the Northeast. But, the model is showing something trying to from off the Southeast Coast.

Looking out a bit farther, We should have a storm trying to get its act together off the Southeast Coast late this weekend or early next week. The NAO is forecast to go back to the negative side around the same time this storm is forming. Right now, the feel I get from the models and other things I look at. The storm looks to be moderate (at least at this time). If you can gather from my wording, I do believe a storm will form. The question is what track will it take and how strong will it be.

 The ingredients for all of this to happen look to be in place.

1) We will have an strong high over eastern Canada and part of New England.

2) The jet stream will help things along.

We will have a split flow; this will help to get something started off the Southeast Coast.   Most of the models are showing a storm forming late Sunday or Monday. The storm won't be a fast mover (again at this time) So it will have time to deepen as it moves up the East Coast.



Euro for Thanksgiving


 If you read my winter outlook. You know forecasters look at a lot of things: ENSO, NAO, AO, jet stream, and the polar vortex (this is just a big area of low pressure sitting over the North Pole). The vortex is key to when and how strong our cold outbreaks occur here in the Northeast. like I said in my outlook. This winter will see swings between warm ups and cool downs. Where am I going with all of this you ask......fair enough......The biggest fly in the ointment, will be cold air. Right now, our air temps next week look moderate for a snow event in the Northeast. And like I said in my outlook, Snowstorms will depend on the timing between the storms and the cold outbreaks.

That's about all I can say about it now, We will have to see if a storm starts to form Saturday or Sunday off the Southeast Coast.    We have over a week for things to get sorted out.........          


Saturday, November 10, 2012

The Official Winter Outlook For 2012-2013 In The Northeast

Hi it's Rebecca here with the third and final part of my winter outlook for 2012-2013. I might refer to two other parts. This outlook will look at the overall pattern and try to give a overview of what the upcoming winter will be like in terms of precipitation and temperature.. The outlook will not tell you how many individual nor'easters, lake effect snow storms, or daily temperatures across the Northeast. I will have a summary at the end. So, if you don’t want to read all through the entire thing, you are allowed to skip ahead. I won’t take it personally. But I will encourage you to read the whole discussion so you can get an idea of what my reasoning was and that goes into making seasonal weather outlook.

Link to part one of this years outlook.

Link to part two of this years outlook.  

The ENSO (El Nino Southern Oscillation):  

Back during the summer of 2012, I pointed out how most of models were pointing towards an El Nino year. Most of the ensembles were showing a weak to moderate El Nino. CFS v1 and CFS v2 showed a long duration weak El Nino. The SST charts backed this up by showing warm water temps off of Peru and extending well into the central equatorial Pacific. Because of this the National Weather Service issued an El Nino Watch.


However, During the fall the warm sea surface temperature anomaly from the central to eastern equatorial Pacific started decaying, It will in all likely hood disappear by early winter. which means instead of a weak El Nino, it will be neutral.


It's a fact that no two ENSO winter seasons are ever exactly the same, and weak El Nino winters in particular can be very different from each other. Because of this it makes it more difficult to make a long-range outlook. The Summer of 2012 is quite unique. They have been keeping records of the ENSO state for the last 63years. In those 63 years we have never seen an El Nino form in summer and fade in September. I have a very good feeling this is one of the reasons for the 2012 Atlantic Hurricane season being so active.

This will have a big impact on our weather in the Northeast and northern Mid-Atlantic states. Generally when the equatorial Pacific is in a neutral state, the polar jet slide south of us into the Mid Atlantic states. It can also cause an increase in the number of Nor'easters that impact New England. One only has to look back at Sandy and the recent Nor'easter a few days ago, to see this is already happening.

elninouse this oneforelnino


Map with data from the National Oceanic and Atmospheric Administration showing the typical effect on North American winters from ENSO El Nino.


              La-Ninathis is the one to use  

Map with data from the National Oceanic and Atmospheric Administration showing the typical effect on North American winters from ENSO La Nina.

                 enso_neutral this might work better  

Map with data from the National Oceanic and Atmospheric Administration showing the typical effect on North American winters from a ENSO Neutral .    

You can see the jet streams all interact differently with each other during the three ENSO phases. All of which has a profound impact on our weather in the Northeast.

NAO (North Atlantic Oscillation):

This oscillation was the main cause for so much cold air in 2010-2011 but also the reason why last winter was so warm. The NAO is a very good indicator of cold air in the Northeast coast. Only problem is the NAO can only be forecasted out 2-3 weeks at the most.

nao_sprd2 current NAO NAM
The NAO has been very persistent in staying negative over the Sumer and Fall. The negative NAO produced a dry flow over New York and New England this Summer, while keeping us away from the searing heat they saw in the Midwest and the incredible drought in the Plains and Midwest. It did cause the Summer in the Northeast to be very dry.

What a negative NAO leads to is blocking over Greenland. During the winter this type of blocking pattern can lead to more storms moving up the East Coast and more arctic air outbreaks in the Northeast. One only has to look at Sandy to see what a negative NAO can cause, the block helped push Sandy back toward New Jersey.

In past outlooks, I've talked about sea ice. The amount of sea ice had been thought to have reached a low in 2007. However back in August of this year. It reached a new low point. Over the last few months it's been coming back. We didn't see a lot of ice melt in 2010-2011 that could have been what lead to the positive NAO last winter.

There is some evidence that supports the idea, of when the polar vortex isn't strong enough to keep the cold air in place over Greenland it leads To a negative NAO. Nature likes to balance things out, so if the arctic is warmer, the temps in United States are gererally lower. The way things are trending we could see a return of a little cross polar flow.  But in spite of all this I don't see enough evidence for calling for a mostly negative NAO , As I pointed out in August this will be a mostly positive NAO this year, and I will stick with that.

 AO (Arctic Oscillation):

ao_sprd2curentAOThis oscillation is also very hard to predict, it only looks out 2-3 weeks like the NAO. But based on many of the same factors that are working on the NAO. It looks like the AO will predominately negative this winter.

Like the NAO, the AO has a huge impact on winter in the Northeast. One only has to look at the two most recent winters to see the impact. We've been tracking the phases of the AO for the last 62 years. During that time, the winter of 2009-10 was the most negative on record. Whereas the winter of 2011-2012 saw the most positive AO on record. So clearly the AO and NAO are going to be big wild cards

PDO (Pacific Decadal Oscillation):

PDO-index-since-1900 The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds. It's normally a 20 to 30 year cycle. The PDO is currently in a cool phase, with the ENSO going into a neutral and a cool PDO, this would lead Near-normal precipitation. Near-normal to a little below-normal temperatures in the Southeast.

With the polar jet dipped down over the Mid Atlantic states, the storm tracks would favor storms moving over the Southeast and then moving up the eastern seaboard. The conditions in the Southeast could intensify those storms a bit more.   

There have been two full PDO cycles in the past century: During 1890-1924 and again from 1947-1976, saw cool phases. Whereas from 1925-1946 and from 1977 through the mid-1990's, the PDO was in warm phase. A look at those decades would show you how winters turned out on average. For instance, the East Coast saw several years of hard winters during the 50's and 60's. Also, a Study by Rodionov and Assel in 2003 showed a direct correlation between weak to neutral ENSO and a cold PDO. The Data showed cold air outbreaks and snowstorms are  more frequent around the Great Lakes.

PNA (The Pacific/North American):

This is one of the most recognized, influential climate patterns in the Northern Hemisphere. The PNA is also a short term forecast. So like the NAO and AO it is difficult to forecast. The GFS ensemble has been handling the PNA very well this year. The ensemble Index Forecast indicated the PNA would be weakly Negative in the November 8-15 timeframe, as you can see that is just what we have. It is forecasting the PNA to go neutral to weakly positive very soon.

pna-5-pgNOAAPNAindexthisis the one I wantto use

Although the PNA pattern is a natural internal mode of climate variability, it is also strongly influenced by the ENSO. The positive phase of the PNA pattern tends to be associated with El Niño (Pacific warm episodes), and the negative phase tends to be associated with La Nina (Pacific cold episodes).

I'm forecasting the PNA to be mostly positive for the upcoming winter. With ENSO El Nino being very weak or most likely neutral this will have an impact on our winter in the Northeast.
When the PNA is positive you normally see ridging over the western U.S., and deep toughing over the east. This results cold arctic air in Canada being forced southeastward, which results in below normal temperatures over the eastern U.S. It also can lead to more winter weather events in the Southeast.

Lake Erie and Lake Ontario water temps:

I put this in for those who live in and  around the lake effect snowbells.  The Big Lakes saw surface water temps that were very high this Summer. However in spite of that , the lakes cooled off very quickly, thanks to the cooler than average fall temperatures. Now there is no correlation between warm lake water temps and the amount of lake effect snow in the winter. Because if there was last winter would have been a bonanza for the lake effect snowbells.


The surface temps for Nov 10 2012 is 50 degrees Fahrenheit. Here is a chart that shows the average water temps from 1992-2010, by month for Lake Ontario. You can see on the bell curve, that the 50F (10C) reading is right where it's suppose to be for this time in November.      


As most of us know, there is nothing carved in stone or certain about a seasonal outlook. There are many variables which impact seasonal weather that are not completely understood. So as you read the results of my research keep that in mind. If there is anything we've learned is that there are several bellwether things that can affect our climate and in turn the weather. As I said earlier there has never been a recorded instance when the a Summer El Nino turned back around into a neutral ENSO. So, I'm sure it will throw curves and cause surprises. The winter of 2012-2013 will be an interesting one to watch unfold.

If you take a look at the ENSO diagrams, in the ENSO section above, see how in El Nino and La Nina years, the subtropical and polar jet streams tend to be further apart and interact less. whereas, when the ENSO is neutral subtropical jet and polar jet converge over the northern Mid Atlantic states. Because the two jets are fighting for the same real estate, there are frequent outbreaks of cold air from Canada as well as frequent warm and wet intervals.  

Ok with all that said, here is my precipitation and temperature outlook for the winter of 2012-2013.   Temperature: It will variable and swing back and forth. We will see moderately long warm spells followed by moderately long cold spells.  Because we're still transitioning into a neutral ENSO, I think the first 1/3 of the winter will see average to above average temperatures. Then we will see more in the way of cold air outbreaks with more in the way of below average temperatures. The temps should turn colder than normal during February. So over all, I think the temps in the Northeast will be slightly below average.  

Precipitation:   As I said, the first part of winter will start off a bit above normal. Therefore, the cold most likely won't phase with the big storms until later in the winter. Some of these storms will make the headlines, since the big cities would be getting impacted by the winter storms. However, the NAO will be a fly in the ointment. So it should a variable, but interesting winter. Time will tell how it all turns out.  

Because of increased Nor'easters, the eastern US will see snow from Alabama into New England. Above-normal snowfall for parts of the Northeast and mid-Atlantic. Up here in the Northeast New York City, Philadelphia , Boston, and Albany will be in the corridor to see above average snowfall. While areas in Central NY, Western NY and PA, and the Tug Hill see more in the way of average snowfall. We will see more clipper like systems this winter, but they typically aren't big snow makers. Therefore, I think based on the pattern that the snow belts will see near average snowfall, when the lake effect machine kicks in.  

As I said, during an ENSO neutral year generally the storm track moves storms across the Southeast, it will be a wet winter for portions of the Gulf Coast and the Southeast. There will be some severe weather worries for those along the Gulf and parts of the Southeast, especially in Alabama and Florida.  

The reason I feel the Mid Atlantic and Northeast will see above average snowfall is an higher than average number of Nor'easters that will track up the coast. Southern New England could do well…A SW flow is often good to them during the winter.  

Ok here are my predictions for snowfall in some of the major cities in the Northeast.

Albany...... 60-75 inches.    
Boston....... 45 -60 inches.    
Buffalo, NY ........ 90 -105 inches    
New York City...... 32-38 inches    
Rochester, NY....... 95-110 inches    
Syracuse....... 120-135 inches    
Utica...... 90-110 inches

I want to close by saying, I can’t tell you the number of snowstorms, for it to snow it has to be cold. since there will be warm spells and cold spells. The timing will depend on a storm moving through when there’s a cold outbreak.

That’s it…..hope you enjoyed reading the outlook.


Monday, November 5, 2012

Will the Nor'easter Stall off of New Jersey?

Here's an GFS automation  starting 7am Tuesday and going through 7am Friday. You will notice at from  7am Wednesday 7am Through 7am Thursday the Nor'easter sits and spins in the same general area where Sandy made landfall. NOT GOOD for the areas that saw the high surge from Sandy, all  barrier sand bars off shore were taken out by Sandy

The midweek Nor’easter

There's no doubt we will have a Nor'easter Wednesday afternoon into Thursday. But, what is in doubt is the track and timing. Both of these things will have a huge impact on who sees what. I would have posted this on my Facebook weather page ; but every time I try to make an album FB post the image separately.      

The upcoming Nor'easter will be moderate to strong. But at this time, it won't be anything like the Halloween Nor'easter we had last year, while it will bring some strong winds especially on the coast , it's not going to be anything close to Sandy.

Map of path
Here is a quick map I drew. It shows the Where our Nor'easter is sitting a Midnight, Just off of British Columbia. The track will carry it southeast and have it off the Southeast Coast Late Tuesday or early Wednesday. The storm will then move up the coast phase with the polar and subtropical jet and rapidly intensify by the time it gets into the Northeast.

gfs_namer_078_1000_500_thickGFSShowingwindon thewestside
  Here's the GFS it's showing a moderate storm of 988mb. It's running a little faster than most of the other models. It has the Nor'easter South of Long Island Wednesday in the 1:00 - 200: am timeframe and moving across New England during the morning on Thursday. It's more to the east than the other models would bring snow for Cape Cod.

Wind3285032and32mslp_North32America_96EUROruning a few hours behind the CMC
This is the Euro. It's running slower than the other models. It tracks the Nor'easter to the east of Delaware Maryland then moves it south of Long Island and moves it into New England. it also phases the storm and jet stream sooner.

Here is the GGEM it's a Canadian model. it's the most aggressive of the models and shows a strong Nor'easter . It has the track a bit more to the east than the ECMWF (EURO).

Here is Canadian CMC it has a track that is more or less in between the Euro and the GFS. The panel in the upper right is the 1000-500 Thickness Chart.....The chart I posted on the other day. It looks different than the GFS thickness chart that I showed you how to read....but you will see it gives the same information.                      


Another model called the MRF the Mid Range Forecast Model. As you can see all the models say we will have a coastal storm…but where is the big question.

Potential impacts from this coastal storm could include:


 They will have Gale Force winds (50+ mph) on the coast, some coastal flooding and beach erosion ( not great news after the massive erosion caused by Sandy).

If you look at all the models they are showing a tighter pressure gradient on the west side of the storm. So during the overnight and into Thursday, inland areas will see some wind as well. In higher elevations the winds could gust up to near 45 mph. But it will be breezy in the lower terrain as well. One threat would be trees and limbs weakened by Sandy would be at greater risk of coming down.  


The coastal areas will see heavy rain. This would cause flooding of poor drainage areas. In Central and Eastern NYS the lower elevations below 1000 feet will most likely see rain.    


Most likely the rain will turn to snow during the overnight going into Thursday morning. The Precip would be heaver on Thursday. How much is the 100 dollar question at the moment. The Nam, Canadian, along with the GFS have the Nor'easter to the east. In fact the latest run of the NAM is looking more like the GFS. However, the ECMWF has it very close to the coast. The Track will most likely be east of the Euro and West of the others. If you look at the Models and the Map I drew you will see there is a large area of  strong high pressure north of the Nor'easter in Canada. This would help in the cold air department as long as the Nor'easter tracks close enough to the coast. If the Euro is right Eastern New York would see a big hit. with Central New York seeing some snow as well. On the other hand, the GFS would basically be a complete miss. With the GGEM, Canadian, and NAM more of a New England event.  

Elevation: will play a role, areas above 1000 feet will have the best chance of seeing snow. From 1000 - 1500 feet it could be a snow/sleet mix. The areas above 1500 feet would have the best shot at seeing enough snow to make it a plowable event, especially in the Catskills and parts of the Capital District (if the track is right).  As you can see there is still a lot to iron out. Namely how cold it will be, timing, and the track of the storm. So it's too early to make any snowfall forecast at this time. It does look like the precipitation will be later in the day Wednesday and going into Thursday. I'm fairly sure the Catskills will see snow, as will those above 1500 or 1800 feet in southeastern NYS. The lower elevations will see mostly rain, with those between the two seeing a snow, sleet mix. As for how much, I just don't know yet.

That's it....I know it's not much.....there is just too much uncertainty to say anything else. I hope to have a better handle on this by tomorrow sometime.


Saturday, November 3, 2012

How To Read a 1000mb to 500mb thickness chart.

I've been posting a lot of 1000-500mb thickness surface charts lately. I sure at least a few of you don’t know how to read it. So, I thought I would post in the blog  how heck you read all of this stuff. I grabbed one of the model runs I posted on my Facebook page earlier today.

gfs_namer_114_1000_500_thick for blog on thicknessThis particular model is called the Global Forecast System or GFS model. The GFS is run four times a day at 00UTC, 06UTC, 12UTC, and 18UTC. The GFS can look out in the future for 384 hours. It's used for short range and medium range forecasting. It is just of many models that we can use, others are the NAM which stands for North American Mesoscale, the RUC which stands for Rapid Update Cycle, and ECMWF which stands for The European Centre for Medium-Range Weather Forecasts (It is more commonly called just the EURO), and many more.    

The Weather models look different from each other, but they work and show more or less the same things. Models show you different layers of the atmosphere; the 250mb, 500mb, 800mb, and many others. The one I will be talking about is the 1000-500mb Thickness Surface Chart.

How do I read the above chart and what does it all mean?

First of all, this is forecasting future weather. In this case, it is forecasting the surface 1000-500mb thickness for 114 hours in advance. The forecasts is valid for Thursday, Nov 11, 2012 at 06 UTC.

How do we know this?

At the top of the chart we see:   11/03/20 12UTC 114 HR FCST VALID THU 11/08/12 06 UTC NCEP/NWS/NOAA

This is what these numbers mean:

11/03/20 12UTC = The date and time the chart was produced.

114 HR FCST = This indicates how many hours out the forecast is valid (114 hrs).

VALID THU 11/08/12 06 UTC = This map is valid Saturday, 12/26/2009 at 06 UTC.

NCEP/NWS/NOAA = Who produced the chart.

What do we see on the chart?

Precipitation: The first thing that pops out are the colored areas. Once such area is multicolored area approaching the Northeast (This is the Nor'easter, I've been discussing on my Facebook weather page). The different colors indicate different levels of precipitation. the lighter shaded green areas indicate light precipitation. The darker greens indicate heavier precipitation, The blues and purple areas are showing very heavy precipitation.

If you look to the left side of the chart. You will see a scale; this indicating the intensity of the precipitation. What it's telling you is how much precipitation will have fallen by the time the map is valid. For example, the light green area over West Virginia on the chart indicates between 0.01 and 0.10 inches of precipitation will have fallen over West Virginia by the time 11/08/12 06 UTC occurs.

Isobars: these are the dark solid lines on the chart. They represent areas of equal atmospheric pressure. Each line passes through a pressure of a given value. There are certain rules you most follow when dealing with isobars

 1) isobar lines can never cross each other.

2) they are labeled every 4 millibars (millibar = 0.02953 inches of mercury). So allowable lines would be 992, 996, 1000, 1004, 1008, and so on.

3) isobar lines are generally corrected for sea level so you can ignore differences in pressure due to altitude.

It's easy to locate high and low pressure zones as a result of the lines on the chart. Furthermore since winds flow from high pressure to low pressure you can predict what the local wind pattern will be when the chart is valid.

Wind: the isobars can also give you an idea how strong the winds will be. When they are very close together; you know the winds are going to be strong. If you look at the area between British Columba and the Yukon you will see a closed isobar with an (H) and the number 1036 under it. This an area of high pressure. Notice there is no precipitation in the center of the High. If you go east or northwest of that area of high pressure you will see the isobars are far apart; this means the winds are light or even calm. However, if you go south of the area of high pressure the line will get closer together. therefore the winds are stronger. The same thing applies to the area of low pressure approaching Long Island, NY. The isobars are very close. So, the winds will be very strong, with the strongest winds at the center. One other thing you could tell, would be the winds would be coming out of the NW over the Great Lakes.

Thickness lines: these are the blue and red dashed lines. The red dashed lines show where the warmer air is and the blue dashed lines show where the cooler air is. Notice these lines have numbers such as 546, 552, 558, 564 etc. The higher the number, the warmer the air temperature.

During the cold season thickness lines can aid in forecasting where frozen precipitation may fall. Forecasting precipitation type during the cold season, is one of the most challenging types of weather forecasting there is. Forecasting precipitation across the United States during the seasons of late Spring, Summer, and early Fall is usually simple. The primary precipitation type in those seasons is rain. However, during winter, the primary precipitation types are rain, snow, sleet, and freezing rain.

There are several ways to forecast precipitation type.

1) using the 1000-500mb thickness method.

2) the 1000 - 850 and 850 -700mb partial thickness method.

3) using soundings method.

Since we're talking about the 1000-500mb thickness chart. That is the method I will explain. But I will answer any questions you may have on the other two.

The 1000-500mb thickness method is a very general method. It can be used to give you an idea of precipitation type over a given area (method#2 and # 3 are more accurate).   In the Northeast and northern Mid Atlantic states, the critical 1000-500mb thickness value that represents the cutoff between liquid versus solid precipitation is 540 line. Other locations across the country could have a slightly different value. For the Northeast lines that have numbers lower than 540 should see frozen precipitation while regions that have a thickness higher than 540 should see liquid precipitation. The 540 line shows more or less where there is a 50% chance for rain versus or a 50% chance for frozen precipitation.

Well, you should know what your looking at and how to read it. I hope you learned something and found this interesting.