Day 3 of Augusta, ME (KAUG)

Sunny skies are competing against strong cold advection this afternoon, with temperatures not rising much but still had a high of 40F due to downsloping ahead of the true cold air mass. As the sun sets this evening, cold advection will win and winds turn from northwesterly to northeasterly as an elongated high pressure area settles off to the north. Meanwhile, the well-advertised elongated low pressure area will approach from the west-southwest. The first round of precipitation will move in tonight from warm advection aloft, bringing a period of heavy snow before tapering off later tomorrow. Although warm advection will occur aloft, northeasterly low-level winds will keep the low-level cold air especially with cold air damming. With this setup, I expect the cold bias the models have had to end and possibly even reverse a bit. With a complete overcast tomorrow, surface temperatures will rise only slightly during the day and then fall slightly tomorrow night. An enhanced surge of northeasterly winds will occur early tomorrow morning which will cause a second fall in temperatures. The winds should not be too strong given the lack of daytime heating to mix down winds from aloft or terrain channeling to accelerate the winds. A more scattered, possibly convective secondary area of snow will move in tomorrow night.

Also, precipitation verification might be a headache. For some reason, the station erroneously recorded 0.10” in a few minutes this morning under clear skies. In addition, KAUG frequently undercatches precipitation (sometimes by a lot) during snow especially if it is very cold and/or windy. This is probably because it is (likely) still using the heated tipping bucket instead of the newer all weather precipitation accumulation gauge (AWPAG) which is much less prone to undercatch. Hopefully, winds will not be strong enough for undercatch to be a big issue.

Source: National Weather Service

Source: PivotalWeather