Day 5 of Watertown, NY (KART)

Mostly clear skies and almost calm wind will lead to good radiational cooling initially this evening. However, as a strong low pressure approaches from the west, the synoptic-scale pressure gradient will strengthen tonight, with strengthening southerly winds. The question is, when does the southerly wind get going? High resolution models indicate that the lingering low-level weak cold air mass, enhanced by some radiational cooling, will pool in the St. Lawrence Valley and extend into Watertown this evening, forming a subtle front against the warming air mass to the south with strengthening southerly winds. The models show the subtle front pushing through KART at around 06z tonight, a bit similar to day 2 but in a less dramatic fashion since the “cold” air mass deposited behind today’s weak cold front is hardly cold at all, making for a very tricky low temperature forecast. It is really hard to tell if it will push in just before or after 06z, so might be good to play it safe. Mostly sunny skies aside from some high clouds tomorrow will lead to a rapid warmup, likely above model guidance (perhaps near ECMWF and HRRR) into the mid-60s, around record highs for late February! The sunshine will also help mix down the stronger southerly winds from aloft. The southerly wind with little or no westerly component will also minimize any moderation off the relatively "cold" Lake Ontario waters. A shower or two is possible tomorrow evening, though precipitation amounts will be minimal.

 

Source: PivotalWeather

Source: weather.us