We’re gearing up for a nasty Christmas storm tomorrow. Today’s weather is rather tame, comparatively, with a little sun and a slowly increasing wind in the afternoon. If you’re running around for last-minute items, the weather will stay dry…
…until after dark.
We could see a few renegade showers break off from the main storm and zip by through the evening and overnight. Steadier rain will wait until after midnight and towards Christmas morning.
We’ve seen events of this kind before: a narrow channel of intense rain (with possible thunder), very strong winds and then an abrupt shutoff. We call it a squall line in meteorology, and while more common in the warm season, it can (and does) hit during abnormally warm surges in the cold season.
Strong mid-level winds typically accompany these squall lines, and with the right conditions – notably the presence of thunderstorms – these winds will mix down near the surface. This creates our strongest wind surges, which will hit in a narrow window on the early part of Christmas day.
Here are the most important points:
The heaviest rain falls 9 a.m. to noon. Streams and small rivers will rise rapidly. There will be some localized flooding of intersections and perhaps some basements.
The strongest winds will blow from 6 a.m. to 11 a.m. with some gusts to 50-60 mph and as high as 70 mph on the Capes/Islands
Temperatures fall in the afternoon. Highs peak near 60 degrees, then drop to the low/mid 40s by dark. There will be a freeze Christmas night.
Charge up your devices, plan for flight delays and cancellations, prep the generators and if trees go down in your neighborhood, plan on a long-duration outage. This isn’t how anyone wanted to spend Christmas, but Mother Nature follows her own calendar.
Cold will follow for the holiday weekend. The sun’s back and so is the quieter weather. Crazy as it may sound, another warm, wet, windy storm could be heading in for New Year’s Eve and Day.
Don’t you dare, 2021.
Be safe, stay healthy, and happy holidays!