D.C. area forecast: Humid with scattered downpours today; muggy until the weekend

* Flood watch until late tonight *

2:00 p.m. update: See this new post: Round of heavy storms possible 4 to 8 p.m. this evening

1 p.m. update: Radar shows scattered showers around the region but nothing torrential.  For now, the worst of the flooding has passed.  However, the atmosphere remains very juicy (dew points from 69-72 in the region at 1 p.m.) and more showers and storms – capable of extremely heavy downpours and even flooding – could well develop this afternoon and evening.  Hence the flood watch through late tonight.

12:20 p.m. update: See this post on the Prince George’s County flooding: Extremely heavy rain swamps Prince George’s County

11:18 a.m. update: A Flash flood watch has been issued for all but far southern portions of the area through late tonight.

10:40 a.m. update: A flash flood warning has been issued for the southern half of D.C. and central Prince Georges County until 1:45 p.m. Torrential downpours continue to slowly advance southeastward in these areas as more rain develops overhead. Areas hardest hit in the last few hours are seeing less activity now, though high water concerns remain due to runoff.

 

9:35 a.m. update: Given extremely humid atmosphere, some downpours have developed spontaneously just northeast of the District. A Flash Flood Warning has been issued for north central Prince George’s County until 12:30 p.m. 1 to 2 inches of rain are possible in a very short time which could lead to flood of creeks and streams and low lying areas.

From the National Weather Service: SOME LOCATIONS THAT ARE AFFECTED BY THE HEAVY RAIN INCLUDE BELTSVILLE…BLADENSBURG…CHEVERLY…COLLEGE PARK…GREENBELT… HYATTSVILLE…LANDOVER…LAUREL…MITCHELLVILLE…NEW CARROLLTON…BYRD STADIUM AND FEDEX FIELD.

This extremely soupy atmosphere could cause pop-up downpours to form just about anywhere into this afternoon…so keep your umbrellas handy.

Today’s Daily Digit

A somewhat subjective rating of the day’s weather, on a scale of 1 to 10.

5
Mixed day with moderate mugginess adding a layer of discomfort

Express Forecast

Today: Partly sunny, p.m. storm chance. Highs: 84-88.

Tonight: Warm and muggy, evening storm chance.  Lows: 65-71.

Tomorrow: Partly cloudy, p.m. storms.  Highs: 85-89.

FORECAST IN DETAIL


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.

The story for the balance of this work week is that yes, it is moderately muggy with risks of roving showers and storms. Meanwhile, the warm overnights require some air conditioning.  But for Washington, D.C. in the summertime, it could be much worse.

Peak temperatures should continue to top out in the 80s (records are in the upper 90s and low 100s this time of year) with afternoon temperature variability due to scattered cloud cover as well as showers/storms.   Tomorrow has the best chance to sneak a bit hotter and maybe touch the 90-degree mark in a few spots, while Thursday looks to be the wettest day.

Despite the complicated weather week, the weekend may still manage to keep our winning streak of nice weekend weather going as it seems like we stay mostly dry with more sunshine and (drum roll, please), lower humidity!

Today (Tuesday):  A very weak frontal boundary snaking along ahead of a low pressure area in the Midwest becomes the focal point of some clouds today as well as some very scattered afternoon to evening thunderstorms (30% risk).  But we should be able to label the day “partly sunny” as temperatures elevate to the middle to maybe upper 80s.  Humidity is about the same as yesterday with dew points in the middle to upper 60s (a bit muggy, but not super-summer humid yet).  Light breezes from the west and southwest at 5 to 10 mph mainly. Confidence: Medium-High

storms_01

Tonight: Some widely scattered evening thunderstorms are again possible (that 30% risk again), but otherwise, plan on partly cloudy skies overnight with lows reaching only down to the middle 60s or so in the outer suburbs to near 70 right in the city with the heat island effect.  Light winds blow in from the south at about 5 mph.  Confidence: Medium-High

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

Tomorrow (Wednesday):  As low pressure in the Midwest slowly approaches the East Coast, we also still have an associated frontal system focusing precipitation pop-ups around the area.   Probability of showers and storms increases to 60%, especially for the afternoon (total precipitation a tenth to quarter inch in more places than not).  Some of these storms may be strong to severe. Temperatures are forecast to again reach the middle to upper 80s with some moderate humidity levels, but the temperature forecast is trickier.  Less showers/storms and a few more sun breaks could advance a few spots to 90F or a bit hotter, while increased cloud/rain coverage during the key afternoon heating times could stall us out in the lower to middle 80s instead.  Light winds come mainly from the south at 5-10 mph.  Confidence: Low-Medium

Tomorrow night: Partly cloudy and muggy again with a continued 60% likelihood of showers and storms, especially in the evening hours.  Lows are again in the 60s in the suburbs to near 70 in the city.  Confidence: Medium

A LOOK AHEAD

Thursday seems like it should be our overall wettest day of the week as low pressure passes to our west and north, helping to enhance shower and storm activity.  Probability of precipitation increases to 70% with some afternoon storms potentially dropping heavier rains.  Highs again should be mostly in the middle 80s with enough clouds and rain risks to create some choppy hour-to-hour temperature behavior.  Humidity continues to be of the moderate variety with dew points in the 60s.   Partly cloudy again Thursday night with lows in the 60s to low 70s and a continued 60% risk of storms and showers, particularly in the evening.  Confidence: Medium

Friday still finds a 40% risk of showers and storms during the day as highs manage to reach the middle 80s by afternoon under partly sunny skies.  But a cool front starts to work its magic during the afternoon too with the dew points starting to fall down through the 60s.  This trend carries into Friday night with lows dipping into the 60s and clearing skies.  Confidence: Medium

The weekend seems as though it will stay on the drier side with lower humidity.  We’re aiming for partly to mostly sunny skies, lower humidity, and highs in the summer-pleasant lower to middle 80s.  Saturday night should be mostly clear with lows in the comfortable 60s.  Confidence: Medium

Also on Capital Weather Gang

Extremely heavy rain swamps Prince George's County