Saturday, January 5, 2013

Weekly Forecasts: Warmth Precedes Sharp Cold Outbreak

Warmth is slated to precede a sharp cold outbreak that will occur in late January and into February. Above is my weekly forecast for January 6 to January 13th. I expect a zonal flow pattern to set up, with the jet stream displaced north and warm air overrunning much of the nation. This will certainly decimate any remaining snow pack, thus warming temperatures even further for areas around the previously snow-covered regions. The Madden-Julian Oscillation will be headed to Phases 5-6 during this timeframe, both of which are favorable for warmer than normal temperatures across much of the nation. As time goes on, the strength of the MJO signal in phases 5-6 is forecast to increase, only increasing the strength of warm air that will be present in the East US.

In Week 2, I expect low pressure to build across the West US and Rocky Mountains, and high pressure will then build on the East Coast in response to such an anomalous low pressure system. Colder than normal conditions will be displaced south, as the Arctic Oscillation goes negative and cold air presses south in preparation for the late January arctic blast. As the week progresses, I expect the low pressure system to move northeast into southern Canada, where it will stick around for awhile and bend the jet stream to provide cold air for much of the Plains. Eventually, it will bleed south and penetrate the entire nation later on in the month, when temperature anomalies as low as 10 degrees below normal could be found- and then some. The North American Oscillation should keep negative through Week 2, allowing for this bleeding cold air to at least try and push east. However, the still-unfavorable MJO and still-negative Pacific North American index (PNA) will inspire a battle to form between semi-warm air and frigid cold air. The frigid air will inevitably win out, but it could be delayed from hitting the East Coast thanks to these other teleconnections.

Andrew

4 comments:

Rob ice said...

Sooo round early February for northeast cold and snow? Starting to think i-95 corridor is going to have about 3-4 weeks of real winter... ..great.

Anonymous said...

So when this cold blast comes in will there be clash between it and the warm air creating any MAJOR SNOWSTORMS for the central plains?
I just want your opinion nothing more becuase I value it and know that its hard to advise your good followers of something weeks down the road. keep up the great work that you provide for us!

Tim Johnson said...

This winter looks like another bust in the east U.S.While the Central and Western U.S get the cold and snow,the East coast gets warmth and no snow at all.Just admitted its not going to get cold in the eastern U.S.

Eric said...

@ Tim Johnson
You obviously did not read my response to you on weatheradvance.com, this winter is not a bust, if you are going to believe a certain idea or forecast you need to have actual evidence to support it, not just observation or based off of what is occurring in the short-term. Thus far this winter, Andrew's forecasts have been just about as good as you could possibly asked for, heck he beat me in the December forecasted and predicted warmth, so I have a lot of respect for him, and wish I had paid more attention to the northern hemisphere snowfall anomaly for October. I am completely behind Andrew and am in very strong agreement with his forecast for late Jan/Feb for the winter to make a comeback and be comparable to Jan 1985 due to stratospheric warming event being induced partially by the Kelvin Wave.