Note: This is the last of the brief updates of the last few days. Daily full updates will resume starting on Friday night.
Temperatures on the 16th slightly cooled down across the area, peaking in the mid-upper 30s inland and low 40s for most other locations, with continued mostly cloudy skies and morning isolated showers in western NJ as a vorticity max moved through with a surface low pressure developing well to the east. Mostly cloudy skies are likely to persist today with highs similar to those of yesterday. Another trough currently in the central US will move through on Saturday, with a weak surface low pressure developing near the area, but with a narrow axis of moderate snow remaining to the west over central PA into central NY as the core of the cold air mass collapses prior to reaching the region, while temperatures remain in the upper 30s to low 40s with scattered rain and snow showers, mainly west of NYC.
With persistent ridging near the western US and a continued progressive flow, another shortwave trough will move through on Sunday and mark another near miss for the area, as the clipper-type system with light snows weakens as it crosses the Appalachians with light snow mostly staying south of the area. Highs will slightly cool down into the mid to upper 30s, remaining the same on Monday but with less cloud cover expected.
The mid January thaw will come to an end on Monday, as persistent amplified ridging in the western US continue with a piece of the polar vortex over northern Canada shifting towards southeast Canada, bringing the frigid temperatures back into that region after a recent temporary retreat into northern Canada. 850mb temperatures of near -18C to -22C are likely, with the coldest temperatures between Tuesday and Thursday; a storm potential appears unlikely to materialize in this time frame, although some of the latest models continue to suggest a minor snow potential on Tuesday. Unlike the last cold outbreak, however, the upper level low will remain north of the US, keeping the core of the cold over Canada, and the air mass will not be nearly as cold as January 7 when 850mb temperatures approached -30C, an anomalous event for this part of the region. While next week will not be as extreme as the early month cold outbreak, it is likely to be similar to typical cold outbreaks seen in recent winters, with highs likely in the upper 10s to mid 20s range, and lows in the single digits for most and low 10s near NYC and the coast. Temperatures are then expected to moderate by Friday into the weekend.