Friday, May 26, 2017

Winter 2016 -2017 was warm but also snowy for many of us.


The very strong El Nino of 2015-2016 ended in April of 2016. At this time it was thought that a La Nina would follow for the Fall into the Winter.  The ENSO neutral conditions did turn to a very weak La Nina. But it quickly faded, leading to ENSO neutral heading into the late Fall and Winter, then we quickly started the transition to another El Nino.  This is the first time we've gone from a strong El Nino to a brief neutral/weak La Nina, Back to a developing El Nino.

The problem was it takes the atmosphere awhile to adjust from one state to another. All of this change in such a short time, made things very complicated and unpredictable.

As the winter progressed we saw SSTs climb west of South America in the Tropical Pacific.  The positive EPO kept the pattern transient; the lack of blocking kept winter at bay.

Adding to this problem we had that warm pool of warmer than average SST in the northern Pacific at the start. But, then the SSTs quickly cooled from the Gulf of Alaska and along the coast west of Canada. This had a big impact on the jet stream, keeping the colder air locked up in western Canada, instead of moving into the eastern CONUS.

Another thing that lead to the warm winter of 2016 -2017 was the warmth in the Arctic. This allowed also helped keep much in the way of cold air invading the eastern part of the CONUS, we just didn't have much in the way of arctic air to work with.

The transience last winter made it impossible for cold and wintery conditions to stay and get locked in. The fast jet stream and lack of blocking were just too much. We got cold, saw snow, then it warmed and the snow melted. Those areas, that had no snow cover stayed even warmer.

Here is a look at winter overall temperatures, along with a look at overall temperatures for December, January, and February. They show that the early cold in December, never returned for January and February, leading to one of the warmest winters on record.

December

 


January

 


February

 


Winter overall

 

The main complaint I've seen directed at me, was the lack of snow in the Northeast.  But there is where the problem starts. It might be hard to believe, but much of New York, New England, into Pennsylvania saw above average snowfall last winter.  The area that saw substantially below average snowfall was the Mid Atlantic.

Here is a map showing how last winter turned out snowfall wise. I've also included a chart that shows total snowfall for eastern cities.





My temperature outlook for Winter 2016-2017 was a complete bust overall. But my snowfall outlook came in very close to what ended up falling.

The pattern that interfered with last winter, is the same pattern that is causing all the issues with spring 2017.

Forecasting weather is difficult, even in the short term. But to try and look out 4-6 months into the future is near impossible. A seasonal outlook, paints with a broad brush and is a bit vague when it comes to some of the details. The only tools I have are teleconnections, climatology, and analogs. I try to fill in the blank spots the best I can. Most of the time my seasonal outlooks are very good and end up close to the way things go down. But like the winter of 2016-2017 outlook they don't all the time.  Comparing my outlook for last winter to the other outlooks from major outlets, mine ended up better than most. One other thing, the Northeast is a very large area, so there will always be winners and losers when it comes to overall conditions.

I've made a couple of post on why last winter went the way it did..... you can check them out.          

Thursday, May 25, 2017

What a difference a year makes:


Last Summer, into December was dry across the Northeast and Mid Atlantic. Here are a few images from U.S. Drought Monitor for 2016, that show how dry we were.

 

The last 60-90 days has been wet across the eastern half of the CONUS.
From WeatherBELL 

Our drought in the Northeast has been erased. It has been replaced with well above average precipitation this Spring.




 

Soil Moisture chart shows just how wet we are now compared to May of 2016.



 

From WeatherBELL

The next 2-3 months look to be a bit wet. Now given the landfall possibilities I out laid in my hurricane outlook. The Northeast could end up with a tropical system bringing a lot of rainfall. So there is a chance we could be very wet by this Fall.

Climate Prediction Center:

Bit of house cleaning:

I've been asked many times, why don't I refer to or show the CPC three month temperature and precipitation forecast outlooks?

My answer is they are not a true forecast. Instead they are based on a percentage of the odds of probabilities. They are rated on an A,B,C score.  A is above average, B is near normal and C is Below normal. With EC meaning equal chance. For example

Forecast probability anomalies OF 20%, 30% and 40% for above normal

imply probabilities for all three classes (above, near, below)OF 53.3% - 33.3% - 13.3% --- 63.3% - 33.3% - 3.3% AND 73.3% - 23.3% - 3.3% respectively.

 

Here is the current CPC three month outlook for temperature and precipitation.

 


Here is the chart I did for my summer outlook. This is an actual forecast that can be verified.

 


Anyway back to my post.  

 

I've been saying for months, that this Summer will be a lot cooler than last Summer. I've been saying average to slightly above average for temperatures. Looking at some of the models we can see they are calling for the summer to be cool.

 

The next 6 weeks are forecast cooler on average in the EPS.

 
From WeatherBELL

The CFS latest run has the nation cool.

 

From WeatherBELL

We have a + Atlantic Multidecadal Oscillation (AMO) and a + Pacific Decadal Oscillation (PDO), this would explain at least in part, why the Spring has been behaving like it has.
 
The +AMO would also help account for the active severe season this year. There seems to be a linkage that shows an increase in the frequency of tornado outbreaks, when we have a +AMO. There is also some evidence that suggest + AMO leads to greater numbers of tornadoes associated with landfalling tropical cyclones.    


The Teleconnections are at odds on the ENSO. Many are backing off from the chance for El Nino developing.

From Tropical Tidbits.

Looking at the surface temperature anomalies  you can see how much colder (relative to average) the Central to Northeastern CONUS has been.
 
 


Since the first of the year, Sea Surface Temperature Anomalies (SSTAs) have warmed in the eastern tropical pacific, but cooled off in the Gulf Of Mexico ( GOM) and western Pacific and  the central Atlantic.  While the northern Atlantic and southern Pacific Ocean have warmed.
 

 
My estimate of the daily Nino 3.4 index is +0.7 which is a El Nino index Value. On the other hand, NOAA has the weekly Nino 3.4 at +0.4, a neutral value.

 
The SOI



I still believe we're going to see a weak El Nino Modoki (central based) this Fall going into the coming winter. If I'm right, we're going to see an active and cold winter for 2017-2018.

This is how things have gone so far, and where things look to head for the next three months.

Well that's about it.

Friday, April 7, 2017

My April, 2017 Atlantic Hurricane Outlook.


Back on March 26th I posted my thoughts on how the hurricane season looked to unfold.  Looking at everything, I really haven't changed my mind. As far as I can see, I was the first or just about the first to post numbers on the 2017 hurricane season. I wanted to post before the Annual National Tropical Weather Conference was held this year.  I also wanted to beat Colorado State University's April outlook. Why? Because I wanted to make it clear that my ideas are sound, and lay the groundwork , by getting my predictions out there first.

The Atlantic hurricane season runs from June 1st until November 30th. But that doesn't mean tropical cyclones can't form before or after those dates.

Back in March, I said my analog years were, 1951,1953,,1957,1972,1997,2015. Since then I looked at and added 1965, 1976, and 2002. All of these years had some similarities to 2017.


Teleconnections:

The North Atlantic Osculation as primarily been positive since January.  So the North Atlantic Sea Surface Temperature (SST) anomalies have been cold. The cooling off of the SST increased in March.  So now we have cool SST in the North Atlantic, cool tropical SST off the West Coast of Africa, with warm SST off the East Coast of the United States. This places the Atlantic Multidecadal Oscillation (AMO) in a basically negative phase.

The  El Nino-Southern Oscillation (ENSO) is currently neutral. I've been posting on My Facebook weather pages, and I also talked about it in my March 26th blog post. So I won't go into a lot of detail on that. But, the ENSO looks to head for El Nino conditions. During the 2016 hurricane season we were experiencing a strong El Nino. Then late in the fall we transitioned into La Nina. During winter 2016-2017 the La Nina stayed very weak. This is one of many reasons why the winter turned out the way it did.

This year I don't think we will see the return of a strong El Nino. Instead I think it will be weak to neutral.  I don't think we will see what could be a El Nino Modoki (Central Based) until at least mid-summer. Right now, the atmosphere is still acting like we have a weak La Nina; it will take awhile for the atmosphere to catch up. So, there wouldn't be Atlantic influence until we get into the hurricane season. 

Predictions from other major weather outlets.

Colorado State University (CSU):

They issued there outlook on the 6th of April, 2017. The team from CSU said they expect 11 named storms, 4 hurricanes, 2 of them major Cat3 or higher.

Accuweather:

 Issued their hurricane forecast April 5th, 2017. They say 10 named storms will form, 5 will become hurricanes, 3 will become major.

Tropical Storm Risk, INC (TSR):

TSR a prestigious private hurricane forecasting company in Britain, issued their hurricane outlook on April 5th, 2017.  They say they expect, 12 named storms, 6 hurricanes, 2 of them major.  

Weatherbell:

They released their thoughts on numbers for the 2017 season, on 31 March, 2017. They have listed, 10-12 named storms, 4-6 hurricanes, 1-2 of them major.

The numbers I released on the 26th of March, 2017:

I said, my early thoughts were, 10-12 named storms, 3-4 hurricanes, with 1 major.

Last season's tropical cyclone numbers:

In 2016, there were 15 named storms, 7 of them became hurricanes, with 4 major hurricanes.


The bottom line:

The combination of a positive AMO and El Nino will increased trades winds over the Main Development Zone (MDZ) of the tropical Atlantic.  We also have those cool SSTs, in the eastern Atlantic.  All of this will severely curtail tropical development in the MDZ for much of the season.  So the odds of Cape Verde tropical storms will be much lower than average through at least mid August.  This same thing happened in 2016. But once we get closer to September we could see the season kick in and become quite active. We could see a few Cape Verde systems during that time.

Those warm SSTs off the East Coast of the U.S., and the warm waters in the Gulf of Mexico and Caribbean will set the stage, for tropical cyclone development in the western Atlantic Basin.  As was the case last year, most of the tropical development should develop closer to the U.S. main land.  The warm SSTs also, increased the odds of stronger hurricanes coming up the East Coast.  I said last season, we would have a major hurricane impact the East Coast. But I was wrong, major Hurricane Matthew scraped the coast of eastern Florida, missing a direct landfall by just a few miles. This year will be different. I'm going back out on that limb and saying we will have a major hurricane strike the US in 2017. 

My Call based on right now, is 12-16 named storms, 5-7 hurricanes, with 2-3 of them major.
 

If I have to adjust anything, I will release an updated outlook, during the last half of May.
 
 

Thursday, April 6, 2017

Summer 2017 Outlook


Despite busting  my winter 2016-2017 temperature outlook, my snowfall outlook got it right for the most part. Which shows, you can get a lot of snow, even during a warm winter.  Summer outlooks are much harder to forecast,  than winter outlooks. For this reason this outlook is a little more limited in scope than my typical winter outlooks.
 

We have a developing El Nino in the Pacific. It won't be as strong as last summer's.  I do think it will act like the La Nina over the winter.  The 2017 El Nino will be short lived. It should be weakening as we head into the upcoming winter.  There is a good chance this will end up being a weak El Nino Modoki event. If this is the case late fall and the winter will see the greatest impacts in the Mid Atlantic and Northeast.






 

Looking at the sea level pressures in the Pacific, the SOI is looking to be negative over the next 6 weeks, This trend looks to continue into Summer 2017.  Those cold SSTs in the Indian Ocean and around Indonesia means this won't be a long lasting El Nino. The upcoming El Nino should end up being quite weak .
 

My analogs  were difficult to compare to this year. But the closest I could find were: 1959, 1960,1961, 1980, 1983, 2002, 2006, 2009. None of these were a exact match. But they were close enough to gather some insight.   (Note: NOAA has been readjusting the old data. This makes past events look cooler than they might have been. ) So that doesn't help.






 

Temperatures:

The summer will start off cool. But then we will warm a little after midsummer. But we're going to see a lot of back and forth between cool shots and warm shots.  Typically transitions from La Nina to El Nino lead to overall cooler summer, especially during the 2nd half of summer.  This is because the atmosphere takes a little time to move from one phase to the other.  Overall, this upcoming summer, looks to be average to  slightly below average in temperatures. 

 


Precipitation:

On my Facebook weather pages, I've been talking about how I expect to see a very active severe season in the Northeast.  Also the threat that I see from close to the East Coast forming tropical cyclones, again those warm SSTs off the East Coast, has to be taken into account.
 
We have an ongoing drought going on in New England down into eastern Pennsylvania , New Jersey, and the Mid Atlantic. This is especially true for Connecticut and Long Island; the rest of the region is doing OK.  There is also drought in the Southern U.S. I do expect to see the active pattern we're in erode quite a bit of this over the next couple of weeks. But these areas will have to be watched. As, they would have a part to play on where the heat sets up.  But I expect to see most if not all the drought in the Northeast gone by July.

I don't anticipate this to be a typical dry El Nino.      

 


Severe:

The severe season  in the Northeast runs from June through August. The Plains will be cooler than average June July and August. This is typical for El Nino years.  With a trough setting up in the Plains. We would see back and forth ridging and troughing over the east coast, with an active storm track looking to be in the cards. Severe weather in the Northeast will ramp up. This should end up a fairly active year for severe weather, with perhaps several severe outbreaks over the region.

 

Bottom Line:

This Summer is going to see temperatures cooler than average in June into July .  Then we will start to see a change to warmer overall temperatures mid to end of July and August.  I expect the temperatures to end up over all average to slightly below average for New England and New York State into Western Pennsylvania. With temperatures  over the rest of Pennsylvania and the Mid Atlantic to be moderately above average.  But we won't have the sweltering heat we had in Summer 2016.
This Summer will see a wet June and July, with things starting to dry up a little in August.  Overall I think precipitation will be above average.  The wild card will be severe season and tropical activity. But if these play out like I think this Summer and Fall could be wet.
 
I will have a separate post on the 2017 Atlantic Hurricane Season, and my thoughts on the Severe Weather Outlook for June through August.

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.