Sunday, April 19, 2015

My First Thoughts On The 2015 Atlantic Basin Hurricane Season.

When I did my winter and the spring/summer outlooks..... I came up with two seasons that matched up well to the 1977-1978 and  2004-2005 that matched up well with the current pattern, Sea surface temperatures (SST).

But several seasons involved the late 1950's into the early 60's.  Those years saw several hits along the Gulf and Southeast Coast.

The Modoki El Nino and the AMO had a huge role in how Winter 2014-2015 and the spring so far have behaved.  And they will play a huge role in this year's tropical season.

The blue (cold) south of Greenland and North of Spain, in the northern and central Atlantic. The warmer yellow/orange shade coming out of the Gulf and Caribbean, and then the Blue (colder) in the southern Atlantic west of Africa.... is the signature of a negative (cold) AMO. During the cool phases of the AMO, the number of tropical storms that mature into severe hurricanes is less than during the warm phases. . During cool phases of the AMO, the numbers of tropical storms that mature into severe hurricanes is less than during warm phases. This is because, when the tropical waves move off the western African Coast, the cool waters interfere with tropical cyclone development. 

If you read my 2015 spring/summer outlook; you know 1977-1978, 1997-1998 and 2004-2005  matched up the closest of my Analog years, with  1977-1978  being an almost exact match.
Both of these analog seasons were Modoki El Nino years. The  past winter and the winter of 1977-1978, behaved very similarity. One of the main reasons is the  Modoki El Nino.  El Nino is a warming of  Sea Surface Temperatures (SST) in the eastern Pacific, where as Modoki El Nino is a warming of the central Pacific. This little difference might not seem like much....but it can make a big difference for weather in the Mid Atlantic and Northeast.  When one goes back to study past years, you see a pattern.  On average the Northeast and Mid Atlantic during Modoki El Nino tend to be colder and wetter than during their El Nino cousin.  There is no doubt that this past winter was cold and snowy. Another  Modoki El Nino  year was 2010, which was a very snowy year.

But as is the case with all weather events, no two El Nino Southern Oscillations (ENSO) are quite the same.

When it comes to tropical activity 1977 -1978, 1997-1998, and 2004-2005 were quite interesting....especially in this fact..... 1977 - 1978, and  were at the lower end of the of the scale when it came to activity, and 2004 and 2005 where at the very top. So clearly there is something else going on.

When trying to get a handle on the tropical season in the Atlantic; one thing Myself and many others look at is a thing called Accumulated cyclone energy (ACE).

ACE is used to  express the activity and destructive potential of  not only individual tropical cyclones, but also for  entire tropical cyclone seasons. ACE is calculated as the square of the wind speed every 6 hours, and is then scaled by a factor of 10,000 for usability. The ACE of a season is the sum of the ACE for each storm and takes into account the number, strength, and duration of all the tropical storms in the season. The random variation of ACE is determined by two sources: the random variation of the number of tropical cyclones and the random variation in the ACE for individual tropical cyclones. There is a large variation in the total ACE from year to year. As you can see ACE is a very complicated subject.

How do the ACE analog years stack up?

 1978 had a ACE value of  62.

The 1978 season had 24 tropical cyclones that developed, twelve tropical storms, five hurricanes two of them major.

1977 had an ACE value of 25  

The 1977 season had six tropical cyclones that developed, five tropical storms, five hurricanes one of them major.

The 1997 season had 8 total that developed, 3 hurricanes, 1 major. That year saw all the activity in the western Atlantic, Caribbean, and Gulf.  

1997 ACE value of 41
1957 and 1958 were two other analog years that did well in the matchup.

1957 ACE value of 84

The 1957 season had 8 tropical storms, 3 hurricanes, which two became major.

1958 ACE value of 121 ACE value of 225
Ten tropical cyclones, seven of full hurricane intensity, five reached major hurricane status, Including Category 5 hurricane Cleo. 

2004  ACE value of 225

The 2004 Atlantic hurricane season Total storms 15, Hurricanes 9, Major hurricanes 6

2005 ACE value of 250
The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history.


My thoughts so far for this year's Atlantic tropical season.

This year the ACE is looking to be in the 50-60 range. But the final calculation hasn't been done yet. So this could change.

I've already gone over the ENSO. But, normally, El Nino results in diminished hurricanes in the Atlantic. But when an El Nino Modoki forms in the Central Pacific, rather than the Eastern Pacific as the typical El Nino event does. There is on average there is  a higher storm frequency and a greater potential for making landfall along the coast of Central America, Gulf coast and the Southeast U.S.

I said in my long range outlook that I felt the current El Nino Modoki, will strengthen and become an eastern based EL Nino later this year.. Most likely at least moderate to quite possibly strong ..then weaken as we head into fall and winter.

If I'm right, this summer into Fall would see more  El Nino like conditions in the tropical Atlantic. Those being increased upper-level winds over the tropical Atlantic creating hostile wind shear. As well as dry and dusty air in the eastern Atlantic.  But then we would see some late season tropical activity.

On the SST chart you can see how the AMO and the  has the Gulf of Mexico  very warm right now.  The Modoki El Nino will also increase the odds for Gulf, western Caribbean, and along the Southeast coast tropical activity.

Here are the tropical weather charts for 1977-1978,2004-2005, and 1957-1958. You can see there is more  tropical cyclone activity in the Gulf and Caribbean, than in the tropical Atlantic.  With tropical systems having a better shot closer to the US Mainland....the odds of land-falling systems does increase a little.



While the Gulf Coast, Florida, up to South Carolina is at a higher risk....... we can't rule out possible problems from tropical systems in the Mid Atlantic and Northeast.  I also can't rule out an early season storm in the Gulf, due to the very warm SSTs..

Right now, I thinking a below average tropical season, with the total number of Named Atlantic Basin storms 8-10 , Hurricanes 3-5, of which 1-2 will be major.  I also think two maybe three systems will make a landfall on the U.S.

Well I've explained some of the climatology that I put into my tropical outlooks...... I will post a final tropical outlook in the 20-27 May time frame.

If you want to look at some of the data I used..... 

ACE Data. 
Modoki El Nino Weekly.

Modoki El Nino Monthly.

Wednesday, April 15, 2015

The 2015 Spring/Summer outlook.

I have received many requests for a 2015 spring/summer outlook. Long term seasonal outlooks are complex, and involve lots of research   A long range outlook isn't a forecast; it is to be used as a guide on how the season should unfold as a whole.  This being said, I am strictly making this forecast based on research from past weather patterns and climatology.  By comparing past years to this year, I put together a forecast in which makes sense to me. I did this same type of research for this current winter.  And if you read and followed it, you will see it worked out very well.  I predicted above average snowfall, below average temperatures, frequent small lake cutter and western runner snow storms, and more than a few coastal storms.  Anyway here goes

Over the last 6 weeks I've been talking and dropping lot of hints about the long term pattern. So a lot of this shouldn't come as a surprise.

Sea surface temperatures (SST)  play a major role on not only the weather in the Northeast, but also across the globe.  The ENSO Teleconnection is a big factor in the weather patterns.  La Nina is described as cooler than normal SST in the Pacific.  El Nino, warmer than average SST. Typically a wetter winter, with longer cold periods and more frequent storms.


The ENSO Teleconnection:

By the end of March 2015, weak El Niño conditions were reflected by above-average SST across the equatorial Pacific. As of the time of this writing, we still have a central based El Nino Modoki.  As we get closer to summer, I think the El Nino will become east based and strengthen a little becoming a weak to moderate El Nino. Then as we get into Fall 2015 will weaken a bit, and  the warmer SSTs will once again shift into the central Pacific. 


A majority of the models are favoring a moderate El Nino pattern. According to the National Weather Service, the chance of El Niño is at 70-60% , with values of the Niño-3.4 index equal to or greater than 0.5oC. There is an approximately 70% chance that El Niño will continue through the Northern Hemisphere summer 2015, and a greater than 60% chance that it will last through autumn.

This El Nino will most likely be moderate to strong....but I think based on the pattern it will reverse back to a central based El Nino (El Nino Modoki) as we get into Winter.

A big part of my long term seasonal outlooks deals with climatology. Looking at past years and comparing patterns allows me to see things that matches the current conditions.  Looking at all the data I found 15 years which had weak El Nino patterns that matched up to the current pattern.

1919, 1920, 1952,1953, 1958-1959, 1960-1961, 1969-1970, 1976-1977, 1977-1978, 1979-1980, 1986-1987, 1990-1991, 1997-1998, 2004-2005, 2005-2006, and 2006-2007.

I also looked at other teleconnections...the Pacific North American (PNA), North Atlantic Octillion (NAO), Western Pacific Octillion (WPO), and Eastern Pacific Octillion (EPO).

Again I found Years where these teleconnections behaved similar to this year. To spare you the details of all of these years. I will just say after comparing past years of all these teleconnections, I found they all contained the years 1919-1920 1977-1978 and 2004-2005.  

The winters of 77-78 and 04-05 matched up very close to winter 2014-2015. using these two years as a guide.... I think I have a good feel for what spring/summer 2015 will behave like.  

The pattern recognition skills I used, allowed me to predict how March and April were going to behave, long before other weather outlets keyed in on. 4-6 weeks ago I said,  once we got past April 10th the weather would feel much more spring like..... a few weeks ago, I also stated that this week would see above average temperatures, then we would see below average temperatures return as we end April and head into May. And then around the 2nd week of May into mid May we would see a giant warming, again well before most other outlets started to talk about it. Why do I say all of this? To give you confidence that my technique is sound and is accurate. No one can predict individual storms weeks and months ahead, but since I firmly believe weather and climate is cyclical, long range patterns can be predicted with some accuracy.    

1977-1978 saw March to July below average in the temperature department. That year also saw April and May drier than average ...then as we got into Summer precipitation picked up some..... becoming a little closer to average over the Summer.

Based on all of this...  I think we will see temperatures below average for April into August, become more seasonal past mid August...but I feel for the Northeast overall. Spring 2015 will end up below average in temperatures .  Precipitation will also be slow to start but by the time we get closer to Summer precipitation should increase closer to average levels, .

Overall this spring and summer will be a cooler than average, with below average precipitation.

A little on the severe and tropical season. 

We are at a near record low in the number of tornadoes in the U.S for this time and date.  While I do think we will see the tornado count pick up across the Continental United States ( CONUS).  I don't see any major outbreaks over the next 2-3 weeks... But 2004 was a very active year when it came to tornadoes.....So  once we get into the 2nd week of May, things could pickup in a big way. 

As for tornadoes and severe weather in the Northeast.... I expect to see a season similar to last year.  New York State and Pennsylvania will become active, I think the tornado count will end up slightly above average,  while New England won't be as active as NYS and PA...I do expect enough severe weather for a couple of tornadoes. The pattern that looks to setup would have the colder air just to our north in Canada with the warmer air over the Mid Atlantic and Southeast States....This could set up northern Pennsylvania, New York into New England in the battle zone between the cooler drier air trying to move south and the warmer moist air to the south. 

During El Nino the Atlantic typically sees a much less active season. This is due to unfavorable wind shear and increased dry and dusty air.  But no two El Nino's are alike..... when one looks at  my analog year ..... Hurricane activity is closer to average...... so we should end up with 10-12 tropical cyclones in the Atlantic basin this year...... I will come out with a hurricane outlook as we get closer to the tropical season.