As the snow quickly winds down, the cold is just ramping up. The story of this week will be the coldest air of the season so far. The cold will begin to gradually abate late in the week while a storm system likely passes to the south, which will need to be monitored this week as it will likely pass nearby New England.
MONDAY-WEDNESDAY
The much discussed Arctic blast will be quickly filtering into New England as the nor'easter departs. This Arctic outbreak will likely peak (or bottom out) Tuesday and Wednesday, though today will still be very cold. This blast will likely be deep and widespread across the central and eastern United States. This Arctic outbreak will bring freezing temperatures and potential snow all the way to the Gulf of Mexico.
Below: Temperature departure from average Tuesday afternoon. The coldest of the temperatures will remain to New England's west and south:
For New England, air temperatures will likely bottom out in the single digits, on either side of zero, for most in the mornings. The northern third of New England and the mountains will likely drop to the -10s. Tuesday and Wednesday will likely see high temperatures in the single digits north to teens and low 20s south.
Wind chill will also be a factor, though winds won't be all that strong. Gusts of 25-30mph will be likely on Monday as the pressure gradient between the departing low and incoming Arctic high pressure will tighten. Winds will gradually slacken for the rest of the week, but it will still remain a bit breezy, creating wind chills in the single digits, on either side of zero, in the afternoons.
Winds will become much calmer in the mornings, allowing air temperatures to bottom out. With air temperatures in the single digits, it won't take much of a breeze to bring feels-like temperatures down to the -10s to -20s. Flow is more from the west rather than the northwest, which does help somewhat in keeping temperatures and wind chills higher than they could have been.
This blast of cold air will be coming mainly thanks to a strong negative Eastern Pacific Oscillation (EPO). When this oscillation is negative, a large ridge typically builds near the Alaskan and western US coasts with a deep trough digging into the central and eastern United States. A strongly negative EPO favors a cross-polar flow from Siberia to move southward into the United States while keeping Alaska very mild (as seen below).
As far as precipitation chances go, the Arctic high pressure will help keep precipitation generally at bay. Some snow showers/flurries will be possible across the north later Tuesday with an area of increased moisture. The high should keep a weak coastal storm well offshore Tuesday into Wednesday. Some ocean enhancement may be able to allow some light snow showers to develop over Cape Cod and the Islands.
THURSDAY & FRIDAY
A ridge of high pressure will shift offshore on Thursday, creating a more southwest flow. This will begin a gradual moderating trend and bring an end to the Arctic outbreak. The warm-up won't be significant and likely remain below average, but temperatures will begin ticking upward. Overnight lows will still be very cold, in the single digits.
Heading later this week, a southern stream storm system will likely develop around the Gulf of Mexico and potentially bring snow and ice all the way to the Gulf Coast on Tuesday. At this point, the large-scale flow pattern doesn't look conducive for bringing the storm up into the Gulf of Maine, but rather shear off to the south of the region.
Below: Upper-level flow pattern later this week, showing a pattern that may not be amplified enough to allow a late-week storm system to move more northward, though trends will be watched:
It'll be a rather close call and a few ensemble members do bring the storm closer to New England (though most support a mostly miss to the south at this point). Cape Cod will stand the best chance of seeing flakes from this system late this week and at least a glancing blow remains possible. Trends will be watched over the coming days.
Below: Current likelihood of minor winter weather impacts on Friday:
Also late this week, the decaying remnants of a northern stream system will likely scoot to the north of New England. This may be able to squeeze out a period of snow showers for the northern tier, but accumulations from just this system would be very light, if anything at all. The upper-level pattern doesn't look amplified enough for any real phasing between this system and the southern stream system, but, again, trends will be monitored.
Below: Weather map for Friday morning showing the northern and southern stream systems separated near New England:
WEEKEND
The very gradual warming trend looks to continue into the weekend. A stronger and milder west-southwest flow looks to take hold as the Arctic air continues to retreat. Highs will likely get a notch warmer over the weekend than where they reach on Thursday and Friday, likely getting back to around seasonal averages.
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