Tuesday, March 28, 2017

Tropical Cyclone information graphics changes for the 2017 season.

The National Hurricane Center (NHC) is making several changes to its tropical cyclone graphics.

The 2017 hurricane season will be here before you know it. So I wanted to go over these changes before June 1st.

1)  The NHC will be issuing advisories even before a disturbance becomes a depression or a named storm.  Any potential tropical cyclones that threaten land area with tropical storm or hurricane force winds within 48 hours will be given advisories, with discussions and tracking maps.

2)  The NHC started posting experimental alerts for storm surge last season. For 2017 those alerts will be mandatory. The NHC will be issuing storm surge watches and warnings for the Gulf and Atlantic Coast, for any storm that has the risk for life threatening surge conditions during any stage of a subtropical or tropical cyclone, even potential tropical cyclones.  

3)  For the 2017 hurricane season, the NHC will be issuing approximate arrival times of tropical storm force winds. The new graphic will display the earliest reasonable arrival time of winds of at least 39 mph.  A probability scale will be used along with the arrival time. The scale will show the probability threshold for 39 mph, 58 mph, and 74 mph wind speed will be met in a particular location. 

4)  The size of the Cone Of Uncertainty will be smaller. The cone will be based on the tracking error over the last four hurricane seasons. The cone doesn't represent where impacts like storm surge, wind, flooding, or tornadoes will be felt.
The old Cone of Uncertainty
The updated Cone of Uncertainty

Table showing the circle radii size of the cone

5)  Advisory graphics will be greatly improved.  New bolder colors and easier to read font should make the carts easier to view and understand.  The new graphics will include tropical storm and hurricane force wind fields.

I hope you found this helpful. As always let me know what you think, or post any questions you might have.

Sunday, March 26, 2017

A first glimpse at the 2017 hurricane season.

With a possible subtropical system developing in the Caribbean, the system could become named, it could even become a full born tropical system . I thought I would post some thoughts I have on the upcoming  2017 Atlantic Hurricane season. This isn't going to go into a lot of detail. There is still a lot of data that has to come in before I can state how things look to go. My official tropical outlook will be released most likely at the end of April.

The first day of the Atlantic Hurricane Season begins on June 1st.  So there is plenty of time to look at the data and trends.

Even though there isn't a lot to go by yet, looking at the current Sea Surface Temperatures (SST)can give us a clue and a few answers.

Here is a look at SST as of 3/26/2017; in it we can see two things. First, is the developing El Nino. The second is the cool water west of Africa, and warm waters off the East Coast of the US. 


The analog years I've been looking at are 1951, 1953, 1957, 1972, 1997, and 2015. Number 1 was 1972 and number 2 was 1997.

The Pacific:

Looking at the tropical Pacific, we see warming in ENSO regions one and two. The current ENSO neutral conditions look to continue for the rest of Spring, then we will transition toward El Nino this Summer , and most likely be in an El Nino this Fall.

History tells us that El Nino's typically inhibit Atlantic tropical activity. The warm SST in the Pacific causes the air to rise over the tropical Pacific. Since weather in the Northern Hemisphere tends to go west to east, that  warm rising air in the Pacific sinks over the Atlantic; this helps stabilizes the atmosphere over the tropical Atlantic. More in the way of stable air leads to less in the way of thunder storm activity.  El Nino's  also tend to cause stronger winds to come off of Central America, these winds extend into the tropical development zone of the Atlantic. The winds shear the tops off of developing tropical cyclones, making it harder for hurricanes to develop. During El Nino years we also tend to see the Atlantic trade winds blow faster. This causes any thunderstorms that do develop to move faster , again leading to fewer hurricanes.

It is still uncertain if El Nino develops, or if it does if the atmosphere will respond quick enough to make a difference.

The Atlantic:

We have cool SSTs west of Africa in the prime development zone.  Tropical cyclones need warm SST's in order to develop. Cooler tropical waters lead to unfavorable hurricane conditions. This along with a developing El Nino means  long track Cape Verde tropical systems will have a hard time this year.

This time of year it's hard to make long term predictions. Why? Because this time of year is always a time of transition.  


It's becoming obvious that the upcoming season will have less ACE points than we saw in 2016.

An article by Weatherbell's Joe Bastardi was shared to me. Here is a few graphics from Bastardi's post. These will prove the point I'm making.
Image credit Joe Bastardi, Weatherbell Analytics
Mean sea level pressures of the 1950's
Image credit Joe Bastardi, Weatherbell Analytics
mean sea level pressure from 2006 to 2016
Image credit Joe Bastardi, Weatherbell Analytics
Image credit Joe Bastardi, Weatherbell Analytics
Image credit Joe Bastardi, Weatherbell Analytics

In the images you can see the warmer than normal SST off the Southeast U.S. and Caribbean

Colder than normal SST off the Northeast and North Atlantic.

So you have higher pressures in the north and lower pressures in the tropical development zone of the Atlantic .

Mean sea level pressures of the 1950's were higher than normal in the north, normal in the Atlantic, and lower than normal in the Caribbean. 

All of this causes tropical storms to  come close to the U.S. Southeast Coast and move up the coast.

SST and mean sea level pressure from 2006 to 2016. This period has seen no official major hurricane strikes on the East Coast, (But I personally count Sandy as a major hit, based on her impact).  

This year will have some similarities to last season.

The SST's are warmer off the East Coast into the Caribbean and Gulf. So, any tropical systems that do develop will develop on the western side of the Atlantic. The closer the storms form to the U.S. the greater the odds for landfalling tropical cyclones on the East and Gulf Coast of the U.S.

My early thoughts on the upcoming hurricane season  is for a average to slightly below average season. Something similar to1972, 1997, or 2015. So  I'm leaning toward 10-12 tropical systems, with 3-4 hurricanes with 1 major hurricane.

The warmer waters off the East Coast, would also help tropical systems retain strength or even intensify as they move up the coast. This would be worrisome, because the impacts could be similar to what we saw during the 1950's.   

That's it for now.


Monday, March 6, 2017

What the heck happened to Winter 2016-2017

When I posted my winter outlook last fall; I thought I was going to make a three pointer at the buzzer and win the game.  For some areas my outlook went well, for other areas so far it's been woefully wrong. While snowfall for Winter 2016 2017 isn't over yet. (Last fall I said snowflake to snowflake), we can see a huge disparity between New York State  and New England compared to the Mid Atlantic.   

Places like Syracuse, Boston, New York City, and Hartford saw above average snowfall (thru the 5th of March). But places like Washington DC,  Buffalo, Baltimore, and Atlantic City saw well below average. Many places on the Tug Hill saw a well above average snowfall...Redfield has seen over 300 inches.

So while New York State and New England (especially northern areas) saw snowfall more or less like my outlook showed. Those in Pennsylvania and the Mid Atlantic surely didn't. The Mid Atlantic fell well below what I thought would happen.

As I've been talking about the last few days on my Facebook Weather Pages. The 10 thru the 20th look to be cold with an active pattern. So there most likely will be more snow, perhaps even in the Mid Atlantic States, how much is yet unclear.

As far as overall temperatures for December to the 1st of March, that I didn't even come close to being right.
Overall temperature anomaly from December 1st to March 1st.

This post will touch on the important reasons winter 2016-2017 turned out like it did.

Why the wacky winter?

When I made my outlook, the teleconnection setup pointed toward ridging out west and stronger troughing in the East. I had thought that we would see more blocking near Greenland. The SST projections supported my thoughts back in Fall of 2016.

The QBO (Quasi-biennial Oscillation)

When I looked at the analog years, everything pointed toward a negative QBO on average for the winter months. But it turned out that the QBO stayed strongly positive for much of the time. I couldn't find anything in the historic record that showed a weak La Nina, lower solar activity, with a positive QBO. Not saying there haven't been, but I couldn't find one. At least until this winter.

The Polar Vortex didn't weaken like the analogs showed it should. This was because the +QBO allowed the westerlies to remain much stronger than average. The stronger PV keep a lot of the cold locked up in northern Canada, with only a few weaker surges of arctic air into the Northeast and Mid Atlantic.

The MJO (Madden-Julian Oscillation)

The MJO is one of if not the major cause of the way winter 2016-2017 went down. The MJO has eight phases some of these associate cold in the East, others associate warmth in the East. The MJO is difficult to use and forecast from, it only is fairly reliable for around two weeks. Because of that it can't really be used to make a seasonal outlook.

For winter 2016-2017 the MJO was very active. This effected  Great Lakes, Northeast, and Mid Atlantic climatology.  Weak to neutral La Nina's tend to be cold and snowy in the Northeast. The MJO was so active that it overruled how a weak la Nina typically impacts the Northeast and Mid Atlantic region.  So we ended up with a warmer and less snowy winter than was expected based on climatology.   


What blocking we did have largely stayed over eastern Canada instead of being farther east closer to Greenland. This aided the troughing in southwest Canada into the western CONUS.

The Pacific:

The ENSO (El Nino- La Nina Southern Oscillation)

Last fall everything in the Pacific looked to support my thoughts. We were heading into a La Nina. But then as we got toward January things started to change, as there seemed to be a transition to El Nino underway. The transition became very clear by February as warmer than average SST (Sea Surface Temperature) returned to the Pacific west of South America. This shift happened very quickly, much quicker than I thought it would. These warm SSTs helped ensure that there would be no locked pattern of cold in the Northeast. 

The EPO (Eastern Pacific Oscillation)

When winter 2016-2017 started the EPO was staying negative to neutral most of the time. This was one of the main reason the first three quarters of December 2016 was so cold. Then things changed, From around Christmas to the end of the month we blowtorched. The last quarter of the month was so warm, that it wiped out all the cold before it, making December above average overall in temperatures.  The Cold came back for the start of January. Then SOI spiked during the last week of December, so I knew a January thaw was on the way. But the thaw went a lot longer than I thought it would. The reason I thought it wouldn't last was the Sudden Stratospheric Warming event that occurred at roughly the same time.  However, when combined with the timing of the MJO going into the warm phases, made sure there just wasn't any cold for it to bring south into the Northeast and Great Lakes. 

The EPO stayed positive for a large part of winter 2017, this assisted the ENSO to keep the pattern transient, The Pacific and Northern Jet were allowed to stream too fast. This helps keep the cold to the north, and greatly reduces storminess along with making an unfavorable storm track for the Mid Atlantic into the Northeast. 

The PDO (Pacific Decadal Oscillation)

We had warmer that average SST in the north Pacific in the Gulf of Alaska and off the Northwest Coast during late fall 2016. As we got into winter 2016-2017 those warm SST cooled quite quickly. This allowed the Jet to keep the cold air bottled up in Western Canada and the Western U.S. If the pool of warm SST had remained, the trough would have come farther east, bringing cold into the Great Lakes and East Coast.

Winter tried to reverse things for the first 10-12 days of February, but the pattern being so transitory ensured nothing could lock in. Se we warmed and torched once again.

There are other minor reasons for the way winter has turned out. But the ones I listed above are the major ones.

Thursday, March 2, 2017

Spring 2017 outlook thoughts.

For about half of you, the winter of 2016-2017 didn't go quite as I outlined last fall. There are several reasons for this which I will outline in a blog post very soon. Winter 2016-2017 will be remembered as a winter with decent precipitation, but with sharp temperature contrast.

Anyway, some are asking for my thoughts on Spring and Summer 2017. So your wish is my command :)

Spring 2017:

We had a short lived La Nina, it is now neutral. But even if La Nina has ended it still going to exert an influence on the rest of March into the 1st week of April.
CFSv2 2 meter temperature outlook.


Past years that looked similar to the current pattern, 1998, 1999, 2002, 2008, 2009, 2011, 2012, 2013. The year that looks the closest to what I'm seeing was 2008 with 2013 a close second.  

March is going to see this battle between warmth and cold continue. But I do see a chance for a major arctic shot of cold air for the end of the 2nd week of March into the third week of March.  So March will see a slow build up to Spring like weather. Could there be a snowstorm during that time? Maybe, but it will depend on timing.  The last week of March into April should see this winters hold break on the Northeast, as the jet stream lifts the cold air north and west back into Canada.

April and May look to be very warm over the entire Northeast and especially so for Maryland Delaware, southern New Jersey, and points south.

The precipitation outlook is looking to be average to above average across the Northeast and Mid Atlantic. Those Sea Surface Temperatures (SST) are way above average. As the coming El Nino strengthens, as we head into Summer, there could be plenty of moisture. Those SST's along the East Coast and in the Gulf of Mexico will play a big role in this year's severe season. 
East Coast SST:
Gulf SST:

Severe outlook:

This year's severe weather season, got an early and deadly start. But years that had a similar setups responded similarly.  April and May could be quite active, with both severe thunderstorms and tornado threats. The Ozarks into the South and Southeast CONUS could see quite a few outbreaks.

Remember, reliable tornado records only go back to 1950. So there isn't a lot of data to look at.

Because the Mid Atlantic, Southeast and the southern states saw a very light winter; There was nothing to cool down the coastal waters. All of this warmth and moisture will be available fuel for severe weather. 2017 will most likely be the most active severe season we've seen in 6 years.

2008 and 2011 were very active. For the Northeast this could be a year more akin to 1998 and 1973, as that southern moisture and warmth move north and clash with the cooler dry air just to our north in Canada.
Summer 2017? 

A quick few thoughts about summer 2017. I think the pattern will allow for a warm and fairly wet Summer across the Northeast. As for hurricanes, it could be similar to last summer with most of the hurricane threats coming into or close to the United States, those dratted warm SST again.  As far as numbers of tropical systems maybe a little less than last year. I will come out with an official summer outlook and an Atlantic hurricane outlook sometime in April.

Images come from WeatherBELL Analytics and NOAA/NCDC.