By Alex Sosnowski, AccuWeather.com Senior Meteorologist
March 27,2015; 11:04PM,EDT
A significant change in the weather pattern is anticipated for much of the United States during the middle of April.
The pattern change could bring some rain and cooler conditions to California and the Southwest, snow for the high country of the Sierra Nevada and Rockies and colder weather for Alaska, according to AccuWeather long-range meteorologists.
The pattern change could erase the persistent chill in the Northeast. The number of days with near- to above-average warmth could outnumber the chillier-than-average days in much of the mid-Atlantic, central Appalachians and the Ohio Valley.
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According to AccuWeather Meteorologist Ben Noll, "If the pattern evolves as we suspect, it will also likely cause outbreaks of severe weather over the Central states as the storms move from the Rockies and onto the Great Plains."
Warm, moist air will flow northward from the Gulf of Mexico on a regular basis, which would fuel potential thunderstorms.
"There will still be some tendency for chilly air to occasionally dip into the upper reaches of the Northeast, from the eastern Great Lakes to northern New England and neighboring Canada, but these areas should get a break as well," Noll stated.
The setup could lead to late-season wet snow events in the upper reaches of the Northeast. While temperatures will trend upward in the region, it could be just cold enough at times for snow during a part of the storms that come calling.
"As we get farther along into April, the chances of a rapid meltdown increase following any big snowstorm, and there seems to be that risk in northern New England and upstate New York," Noll said.
Several indicators are suggesting that the jet stream will shift position from its persistent or re-occurring southward plunge in the East.
"A northward bulge in the jet stream is likely to develop in the East with a southward dip in the west about a week or so into April," Noll said.
The jet stream is a high-speed river of air high above the ground that separates cold air to the north from warm air to the south. This change in the jet stream position will set the pattern change into motion.
According to AccuWeather.com Meteorologist Mark Paquette, "We expect an area of high pressure over the western part of the Atlantic to get stronger and create a south to southwest flow of warm air in the East."
"Lengthening daylight will erode the cold air over central Canada, which has been a stubborn source region for the chill in the Northeast," Paquette said.
The longevity of the overall pattern, once it begins, is a question.
There is the possibility that after a week or two into the new pattern it could regress or flip back-and-forth between chill in the East versus the West.
- Christian GundermannAnd the other issue is that, whether it cools down or warms up, either way it always tends to bring more moisture. In the winter I can deal because snow can be removed (as long as it IS actually snow), but rain can't. Dreaming about desert climates!! I wish we could have some of that West Coast drought over here....
Christian GundermannEverybody always comment about cold or warm. All the long-term forecasts are concerned with whether it warms up or cools down. What I want to know is the precipitation trend for New England. I don't care so much one way or another whether it's warm or cold. You dress accordingly. The constant slush, rain, drizzle, sleet, rain patterns turn our little farm into inoperable muc and mire. But I suppose long term predictions about moisture are even more unreliable than about temperature trends.
Wayne Langhuber · Top Commenter · Tax Specialist at Professional Tax and Accounting Sevices LTDI think this was predicted in the spring outlook. I also think that this is a longer term pattern change. The I-95 corridor has seen normal summers the last 2 years. The area has not had 2 normal/below normal summers in a row since the late 70's. 2013 and 2014 were normal in m area (Southern Pa). So I think that while the east will still have its share of cool snaps even with the new pattern I think that in late May-early June summer conditions will return and a hot summer is in store for the I-95 corridor. Accu Weather did predict a warm May for the east coast and NWS seems to be indicating a hot summer east of the mountains in the NE/Mid Atlantic. The much below normal temperatures of Feb-March may be a distant memory by June.
Carlitos Betancourt · Top Commenter · Monsters UniversityI want the SW to cool down we are looking at high 90s possibly 100 for tomlrrow Saturday! :(
Dorothy Ayer · Top Commenter · Owner/operator at Court Reporter
Meteorological Weather LabGreat... The Snow haters are loving this...
Grant McGuire · Top Commenter · Western Connecticut State University
Tom Atvrider · Network Engineer at Westfield State CollegeI am very skeptical. I bet big money on the opposite..Continueing way below normal temps. Not that I won't be happy if it does happen.
Aaron Ginther · Top Commenter · Lynchburg, VirginiaI think we're done with the cold in the lower Mid-Atlantic (MD, DE, VA) after this weekend. There may be some chilly shots but as far as prolonged cold, I'd say those days are over. March has already improved from January and February here. However, the lingering cold air may still hang around in New England after a surge of warmer air mid month.
Cory Morrison · Follow · Top Commenter · Filing/Inventory Clerk at Independent Distributors Inc.I agree with Sal. Even if the cold pattern does ease in mid April, it may only be temporary unless if the GOA waters cool considerably.
Salvatore del Prete · Top Commenter · Southern Connecticut State UniversityEl Nino development will have to be monitored which could change the Pacific Sea Surface anomalies , that could alter the situation some but I still think it will not be strong enough to really change the dynamics. The warm water off the U.S.A /Canada West Cost has been the player as far as I am concerned in the persistence of this pattern.- Wayne Langhuber · Top Commenter · Tax Specialist at Professional Tax and Accounting Sevices LTDA strong Bermuda High will offset the warm Pacific Waters and could mean a hot summer for areas east of the mountains. We will have to see how strong the Bermuda High is and the position it is in. Cold fronts often come to a dead stop in the summer. So even if the Pacific waters remain warm I think that the below normal temps shift into the Upper Midwest and a battle zone sets up in the Mountains. Areas east of the Mountains could see lots of high heat this summer and also lots of strong/severe storms in the afternoon.
- Salvatore del Prete · Top Commenter · Southern Connecticut State UniversityThe -PNA forecasted by the models into April , is behind this reasoning to some degree or another.
- Salvatore del Prete · Top Commenter · Southern Connecticut State UniversityThis new pattern will not hold if it comes about as has been the case for the past two years. It is simply a waxing and waning of the current pattern with seasonal considerations superimposed upon this current pattern giving it a different configuration from time to time as has happened over the past two years.
This present pattern we have been having will be here more often then not unless the sea surface temperature anomalies change especially in the Pacific.
The models have been wrong on this pattern for two years as has been evidenced by the wrong winter forecast they have forecasted for the United States for the past two years.
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