11:15 p.m. Update: Despite persisting pockets of heavy rain, storms are weakening (and lightning is diminishing) as they slowly sink south and southeast through the southern half of the area. These showers and storms should gradually rain themselves out as they head toward or into Stafford, Charles and Calvert counties. How about tomorrow? Looks like partly sunny skies, still kind of muggy, and highs in the upper 80s with only a slight chance of a shower. Do note that a Code Orange air quality alert is in effect for the area tomorrow, which means air pollution could become unhealthy for sensitive groups including children; people suffering from asthma, heart disease or other lung diseases; and the elderly.
10:30 p.m. Update: The good news is there are no severe warnings in effect for the D.C.-Baltimore area. Bad news is a ton of lightning is moving southeast into and through the District during the next hour. Some weaker storms are affecting areas west of D.C. along and south of I-66, and east of D.C. mainly north of Rt. 50, but edging to the south.
A lot of lightning moving into NW DC. Current lightning (in-cloud & cloud-to-ground) courtesy NASA pic.twitter.com/mOpM5NlV89
— Capital Weather Gang (@capitalweather) August 4, 2014
9:30 p.m. Update: There are currently no severe warnings in effect locally (a severe thunderstorm warning is in effect for northern Baltimore and Baltimore County). But strong storms continue to advance east-southeast through Montgomery County, now approaching Rockville and Olney, and then likely into the southern part of the county including Potomac and Wheaton. Again, large hail has been reported with these storms along with strong winds. This is all part of a broken line of storms stretching from northern Fauquier County northeast to north of Baltimore, which should continue to move south and east across the area over the next couple hours.
8:55 p.m. Update: A severe thunderstorm tracks east across northern Montgomery County during the next hour, while another severe storm in Carroll County is now moving east into Baltimore County. With both storms, quarter-sized hail and damaging winds near or past 60 mph are possible, along with heavy rain and lightning. Elsewhere, to the north of D.C. storms are oozing southeast into Howard County, while to the west storms are expanding southeast into southeast Loudoun County.
8 p.m. Update: Storms to the north and west, now moving through the Frederick area with heavy rain and a lot of lightning, are threatening to track east-southeast into and through the D.C. metro area during the next few hours. That is if they hold together. Currently there are no severe warnings in effect. We’ll update here and on our social media feeds as needed.
FORECAST IN DETAIL
We’re in line to see occasional shower and storm risks the next several days, but no surefire washouts, as an upper-level area of low pressure sets up over the area. Much of today may in fact end up on the dry side, though the same may not hold true this evening. With a good mix of clouds and sun, we’re not looking for any bouts of real heat through the week ahead. But with highs back into the 80s and a good amount of humidity, it still feels plenty like August out there.
Today (Sunday): A 30% chance of light, early-to-mid morning showers should give way to another day of broken cloud cover. Most of the daytime should be on the dry side as we’re in between impulses moving through the atmosphere. But with moderate humidity and highs warming to the low 80s, enough instability should build that we can’t rule out a couple of stray showers. Otherwise, it’s partly sunny with light winds. Confidence: Medium-High
Tonight: Shower and storm chances rise to around 40-50% this evening into the early part of the overnight as an upper-level system sweeps through. The best chance of getting wet looks to be in the approximately 8 p.m. to midnight window. Skies are mostly cloudy through the night with lows in the mid-60s to near 70. Confidence: Medium-High
For related traffic news, check out Dr. Gridlock. Keep reading for the forecast through the midweek…
Tomorrow (Monday): To start the work week, it looks like a fairly run-of-the-mill summer day around here. We may see sunnier stretches, but probably cloudy periods as well. With a warm and somewhat muggy air mass in place, there’s still a minor (20%) chance for a shower or storm to pop, mainly in the afternoon or evening. Highs rise into the mid-to-upper 80s. Confidence: Medium
Tomorrow night: Other than the 20% chance of an evening shower or storm, skies are partly to mostly cloudy through the overnight. With little wind to speak of it should feel kind of sticky, with lows ranging from the mid-60s to low 70s. Confidence: Medium
A LOOK AHEAD
The vast majority of models keep what is currently Tropical Storm Bertha well away from the East Coast as it tracks north-northeast across the Atlantic Ocean during the midweek. That leaves our weather largely unchanged for Tuesday, with partly sunny skies, highs climbing to the mid-to-upper 80s, and a 30% chance for scattered showers and thunderstorms in the afternoon or evening. Tuesday night lows bottom near 70. Confidence: Low-Medium
An upper-level impulse swings through on Wednesday, which could increase storm chances, though forecast confidence is not high with this pattern. Prepare for a partly to mostly cloudy day, with a 50-60% chance that we’ll see a period of showers and thunderstorms. Humidity is still on the soupy side, though not oppressive, with highs somewhere in the 80s. Confidence: Low-Medium