D.C. area forecast: Heavy rain possible tonight into Monday

* Flash Flood Watch Through Monday Night for D.C., Montgomery, Fairfax, Prince George’s and Howard counties *

9:15 p.m. update: Lots of potential for heavy rain tonight, as deep feed of moisture from the south spreads over the region. See the regional radar to get an idea of the rain coming north. Localized amounts of 1-2″, perhaps even a bit more, are possible. Some of the heaviest rain may fall right along or just west of the I-95 corridor. Be prepared for the possibility of flooding in some spots overnight (poor drainage areas, creeks/streams, etc.) and remember to not drive across flooded roads. Turn around, don’t drown. Also, be prepared for a possible slow morning commute.

10:05 a.m. Update: An area of showers, some briefly heavy, will pass through the area from south to north now into early afternoon. So rain chances pop up to around 60% over the next couple hours.

Today’s Daily Digit

A somewhat subjective rating of the days weather, on a scale of 1 to 10.

5
A 50/50 day with peeks of sun, higher humidity, and shower/storm risk mainly holding off until later in the afternoon.

Express Forecast

Today: Partly sunny and humid. Passing a.m. shower? 40% chance of p.m. t’storms. Highs: Mid-to-upper 80s.

Tonight: 50% chance of showers/t’showers. Lows: Near 70.

Tomorrow: Partly to mostly cloudy, humid. 40% chance of showers/t’showers. Highs: Low-to-mid 80s.

FORECAST IN DETAIL

Plenty of moisture riding up from the south means the potential for occasional downpours over the next few days. But in this kind of pattern, the timing and placement of showers and thunderstorms is nearly impossible to nail down. And some models indicate the best chance for an extended period of rain holds off until Monday night into Tuesday. The uncertain rain threat plus higher humidity may frustrate some, but surely they are a far cry from the upper 90s heat we were experiencing exactly one year ago post derecho.


Radar & lightning: Latest D.C. area radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Today (Sunday): Perhaps a quickly passing early-morning shower. Otherwise, it’s fairly tranquil into early afternoon with a mix of sun and clouds. Humidity levels are more uncomfortable than Saturday, but we’re slightly cooler in some spots with highs topping out in the mid-to-upper 80s. By mid-to-late afternoon we have a 40% chance for scattered showers and thunderstorms. Any storms could be strong with heavy rain and gusty winds. Winds are from the south around 10 mph. Confidence: Medium

Tonight: Showers aren’t a sure bet, but chances rise to 50% for the evening and overnight hours with embedded thunder possible as well. Again, where it does rain it could be quite heavy. Lows drop to near 70, while winds settle down to near 5 mph. Confidence: Medium

For related traffic news, check out Dr. Gridlock. Keep reading for the forecast into midweek…

Tomorrow (Monday): Hit-or-miss showers and thundershowers are the main concern. Rain chances through much of the day are about 40% for any given location, before rising toward evening. Any showers that develop could be heavy-rainers accompanied by gusty winds, but the severe threat is on the low side. Highs only reach the low-to-mid 80s under partly to mostly cloudy skies, but the humidity stays uncomfortably high. Breezes arrive from the south near 10 mph. Confidence: Medium

Tomorrow night: As you might expect, the shower/storm risk remains the focus of the forecast, with chances up to around 60% through the evening and overnight. Lows fall to near 70 again with mostly cloudy skies and a continued humid flow from the south. Confidence: Medium

A LOOK AHEAD

A wave of moisture riding along a stalled-out front on Tuesday looks to give us our best chance of an extended period of steady rain, especially early in the day, as plenty of clouds aim to hold highs in the low-to-mid 80s for a second straight day. Rain chances should wane a bit for Wednesday as the front retreats westward. But with high humidity still in place, partial sunshine and warmer highs in the mid-to-upper 80s could spark some afternoon/evening showers and storms. Confidence: Low-Medium

Dan Stillman contributed to this forecast.

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