PM Update: Shower or storm possible as a cold front brings us a day of below

Sep 12, 2023

So far, showers and storms have been very few and far between (sorry gardeners and farmers) but we could still see a few pop-up in the area through tonight as temperatures fall and cool breezes rise. Tomorrow's 70s are pleasantly below average, as cooler and drier air swipes us briefly from the far northeast, near Labrador.

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Through Tonight: Easterly breezes gusting near 25 mph may only slowly settle by dawn. Clouds and rain chances increase a bit more as the night progresses. A passing shower or storm is possible as the back-door cold front continues to move southwestward through the region. We don't expect anything too heavy or long-lasting. Low temperatures dip into the 50s.

View the current weather at The Washington Post.

Tomorrow (Sunday): Clouds slowly decrease as east and northeasterly breezes off the Atlantic slowly turn toward a drier northerly and northwesterly direction during the afternoon. We may not be fully, reliably sunny until late afternoon. The change in wind direction helps remove our marine layer of oceanic air that's kept us a bit socked in, especially during the morning. Early morning rain chances and breezes are scant but don't be surprised at a couple rain drops or a quick gust.

A few late-day north-northwesterly wind gusts near 20 mph are possible. High temperatures aim about five degrees below where they normally are this time of year, hitting the mid-to-upper 70s in most areas. Low temperatures overnight dip back down into the 50s with skies staying clear. Light and occasionally noticeable breezes remain possible.

See Ian Livingston's forecast through the start of the workweek. Follow us on YouTube, Facebook and Twitter if you haven't already. Be sure to check out our Instagram, too.

Arriving closer and closer to D.C. this afternoon and evening is a somewhat narrow piece ("tongue") of cooler, less-humid air from around the Labrador Sea offshore of Canada. I argue that the source of our air pushing into our region behind this back-door (moving from northeast to southwest) cold front has traveled up to 1,750 miles to get here.

Luckily for us, we’re at the edge of the southward push of this air, and we’re only getting sideswiped by this cold (30ºF) high pressure sitting in the Labrador Sea — the source of this cool air heading toward D.C. Funneling down the coast from Canada through New England toward us, the air mass's long path is moving along northeasterly winds (See the above windy.com graphic) driving the cooler wedge of air southwestward.

The Labrador Current is known as a very conveyor belt of water that moves southward from near Greenland. It's the balancing act to the Gulf Stream moving warm water northward from near the tropics. These two ocean currents are the ocean circulation engine for our part of the world and are very important for balancing the heat content of our hemisphere.

Luckily any cool-air shock for the D.C. area is very limited for us this time. This air really only sticks around about 36 hours in our region before it retreats back out to sea, toward its source region far to our northeast. And, when traveling as far as it has, the air has modified and been warmed as it's traveled away from the cold water of the Labrador Sea.

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