Trailing Edge of Squall Line

Winter weather returned with a vengeance on the heels of a distinct and vigorous squall line.

A temporary warm-up from the recent record cold was interrupted in the afternoon by a very strong squall line that passed through the Portland area starting at around 2:30pm. The Dew Point at 2:30pm at WeatherMaine was 30°F ahead of the squall line. A rapid drop in dew point was observed at WeatherMaine's South Portland, Maine location. By 6:30pm had already dropped to -6°F! That is a 36° drop in 4 hours, or 9°F per hour! A marked temperature drop was also observed, dropping from 32°F to half of its value,16°F, at 6:30pm.

Visibility on I-295 was reduced to almost nil during the onset of the squall. As typical of most squall lines, this one was distinct and brought with it heavy snow bursts and strong winds; 26 mph wind from the NW was observed at WeatherMaine for many hours following frontal passage.

ven more impressive is the drop in temperature after the frontal passage. The temperature at WeatherMaine at 2:20pm on 1/13/04 was a relatively warm 37.5°F, but at 2:20am on the 15th the temperature had dropped to -5.4°F, a change of over 42°F in 12 hours! This is the most intense 12-hour temperature change noted at WeatherMaine is its history.
More record cold and extreme windchills are expected for the next few days in Maine.