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Tuesday, March 24, 2015

Milder air trying to find an open road to Vermont but cold air will remain a force into April

Some chinks in the armor are finally starting to appear in the winter 2015 frigid and snowy reign.  This in spite of a incredibly cold stretch of recent days when, over a 48 hour period, readings failed to break 20 degrees. Generally speaking, the pattern is expected to remain cold, supported mostly by a large ridge jet stream level ridge over the northeast Pacific Ocean and Alaska. This ridge is expected to gradually lose some intensity and migrate westward in the first week of April allowing some tightening of the Jet Stream in the Pacific and a less supportive EPO index for cold and snow across New England. The cold however will remain a prominent force in the short term and a less persistent part of the medium and long term weather picture as well.


In the short term, a temperature moderation will ultimately lead to a 36-48 hour thaw. A two-faced system in the Rockies will approach and do so with a rapidly eroding area of cold. The first area of low pressure will move northeast through the eastern Great Lakes Wednesday allowing milder air to encompass the region by Wednesday evening. Light rain and a few pockets of freezing rain are possible Wednesday evening along with temperatures in the 30's. On Thursday the jet stream will amplify ahead of a 2nd area of low pressure. This storm will have the ability to gather more significant amounts of moisture from the Gulf of Mexico before its northeastward ride toward new England. With the pattern more amplified and the cold scoured out of New England by Thursday morning, the day is shaping up to be mild, wet and certainly melty. Temperatures may approach 50 during the day at low elevations and 40-45 at the summits. The rain on Thursday could also be heavier for time amount to almost a half inch of liquid. Much colder air will slowly advance back into the region Thursday night into Friday and the snowflakes should be flying through most of the day Friday. A light accumulation is possible Friday but it doesn't look like anything more than that right now.


Both weekend days look chilly and generally sub-freezing even at the low elevations. Flurries could linger into Saturday morning but the afternoon into Sunday appear dry and Sunday in particular should feature sunshine and some excellent visibility. A clipper system will approach Sunday night and brings the next real chance for snow. This particular system looked more vibrant on the models a few days ago and models are currently showing that this clipper will fail to fully re-amplify the pattern going into the early part of next week (the last two days of March). Still, a few inches is likely out of this and the month is likely to finish out on the chilly side with a continuation of mostly sub-freezing temperatures on the mountain.


By April 1, much milder air will begin competing for control of the weather in New England stemming from some of the changes discussed in the opening paragraph. Ensembles are still indicating that the cold air will win most of the battles but the center of this cold will retreat into Canada allowing for a sporadic very spring-like day. The southern branch of the jet stream is responding to what appears to be a strengthening late season El Nino. This means that in spite of the weakening cold, the right set up could still bring a late and very big winter storm to Vermont in early April.

1 comment:

gbc said...

josh, thanks for all your work this incredible winter. I know i speak for many who really appreciate what you do.

Gary