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Active, transitional pattern this week

Despite that fact that we continue to work farther and farther away from Winter with each passing day, the pattern over the next week will feature a transitional — and colder than normal — airmass on multiple days. As we mentioned last week, the presence of high latitude blocking will be the main culprit in driving cold air southward from Canada into the Northern 1/3 of the United States. Despite a changing sun angle and nearly completely melted snowpack, the potential for cold and at least some snow is anticipated to continue for the next 7 to 10 days. This week will feature a transition from a benign pattern into a more stormy one.

After  a warm and pleasant day on Monday, a frontal boundary is expected to pass the area on Tuesday with blustery winds and showers which may end as snow showers throughout the area. This will all be owing to the southward extension of a lobe of the Polar Vortex, which will be elongating and setting up shop over Southeast Canada. Very cold air — 850mb temperatures of nearly -30 C — will be bottled up just to the north of New England. And frontal boundaries will progressively seep this air southward into our area at times.

Meanwhile, an active southern stream will eject weak disturbances eastward from the Southwest United States into the Central United States and eventually off the East Coast. As you may expect, forecast models are struggling with pinning down the intricacies of these individual disturbances. Where they track, their strength, and the positioning of the Polar Vortex lobe to our north will all be essential in forecasting the sensible weather impacts these disturbances will have on our area.

GFS Ensemble mean showing high latitude blocking displacing a piece of the Polar Vortex over Southeast Canada.

GFS Ensemble mean showing high latitude blocking displacing a piece of the Polar Vortex over Southeast Canada.

The initial threat for precipitation looks to come from an ejecting disturbance during the middle to latter half of this week. The correct timing and strength could lead to winter weather throughout the area, but more likely than not the storm, if it impacts us, will feature mixed precipitation areawide. A second threat for wintry weather looks likely next weekend as the Polar Vortex lobe consolidates and swings southward through New England. Nevertheless, the details are uncertain and it leaves us without any true clues as to how impactful any storm may actually be.

The general theme, however, is that Spring will be put on hold for now. For the next 7 to 10 days, colder than normal air and winter weather threats will hang around in the forecast — just long enough to make it seem like this long, cold winter may truly never end.

ECMWF announces major upgrade

The European Center announced a major upgrade to their ECMWF weather model which will be implemented on April 14th, 2015. The upgrade includes new model fields such as Precipitation Type and an upgrade from 4DVAR initialization to TL255. Testing has shown significant improvements in forecast verification.

For more information visit the official release from ECMWF’s website here.

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