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.