Had the right idea on the extended mild period from around the holidays through January, but it was more extreme than I had thought.
Protracted Mid-Winter Thaw More Extreme Than Expected: February Throughts
January Review
Here are the expectations for the month of January as expressed in the 11-13-19 Eastern Mass Weather Winter Outlook.
"January remains fairly active, at least throughout the first half. The PNA ridge begins to erode, however the PV may be undergoing some dysregulation, so the PNA relaxation may be offset to a degree. Departures normal to -1 NNE, normal to +1 for SNE and the mid atlantic".
Eastern Mass Weather 11-13-19-
Here is how the month verified:
While the general theme of a mild month was correct, the southeast ridge was more prevalent than expected and the Pacific more hostile than anticipated. Thus the month was even milder than forecasted.
February Preview
Last fall, Eastern Mass Weather expected that February would also be mild due in large part of a persistent RNA pattern. However the development of blocking late in the month is more precarious. "Full-fledged RNA ensues for February, as any influence that weak el nino or warm-neutral coupling had established may die. In The polar vortex will need to relent, or this will be a very mild month with the storm track west. +1to +2 throughout the northeast. +2 to +3 in the mid atlantic. Beware an eventful president's day should blocking establish itself. February 17-March 2nd may be conducive".
Eastern Mass Weather 11-13-19-
"Winter will be waning long before month's end in the absence of high latitude blocking, given the hellacious southeast ridge in place. However at least some sustained blocking is likely. Since there will be cold air lurking to the north at the very least, this does not look like a "dead-ratter", even without blocking".
Eastern Mass Weather 11-13-19-
How quickly winter wanes should be dependent on the degree to which the polar vortex can become consistently dysregulated, however as it appears to remain rather resilient at least throughout the first half of February.
Polar Evolution
The polar vortex is obviously stout and centered near the pole to begin the month of February.
However it does look to withstand a minor assault next week, which may coincide with a wintery overrunning threat.
Here is the forecasted behavior of the polar domain, which is congruent with the forecasted behavior of the polar vortex.
The winter storm threat next week that is concurrent with the relaxation of the well defined polar vortex is apparent on ensemble guidance. The battle between the pressing cold and the southeast ridge owed to the RNA is on. However the descending EPO should ensure a cold air source.
Snow or a mix (sleet, rain, ice) is likely to the north of the Mass pike, and a mix or rain is likely south.
The following week, or the second week of February features a recovering polar vortex, which has been a theme throughout boreal winter 2019-2020.
But there are some signs that it may endure at least a slightly more sustained attack beyond mid month, which is when conditions should become more favorable for the second major winter storm of the season between February 17 and March 2. The overall tenor of March may very well be contingent upon how quickly and proficiently the polar vortex can recover yet again.
