Worst of storms exiting, but keep an eye out for high water this evening

Expect water levels to recede over the next couple of hours. Of course, we still urge caution as streams are high and some roads still have water covering them. Do not attempt to cross a flooded road in your car, turn around and find another way.

Remarkably, Reagan National Airport registered 1.12 inches of rain from the storm between 5 and 6 p.m., pushing its monthly total to 7.27 inches. This May now ranks as the 8th wettest on record, with more than a week to go.

Rain has already ended west of the Beltway and should end inside the Beltway over the next hour (allowing the Nationals game to be played), and then east of the Beltway by around 8 p.m.

We could see some scattered showers and storms later tonight as a cold front approaches the region. This is our last update in this post. For the forecast through Wednesday, see our PM Update.

5:40 p.m. — Areas of flooding inside Beltway as heaviest storms move southeast

Some of the heaviest storms have moved southeast of the District toward Clinton in Prince George’s County and Waldorf in Charles County. This activity continues pushing southeast, and a severe thunderstorm warning continues for this zone through 6 p.m. Some pockets of very strong winds are possible here.

Inside the Beltway and to the south and west, although the worst of the storms are over, there continues to be moderate rainfall. Due to the saturated ground, water is running off and ponding on roadways causing flooding. Definitely allow extra time for the commute home.

5:15 p.m. — Flooding all over the Beltway, indoors and out

It’s not just flooding outdoors, it’s also flooding indoors — specifically, at the McPherson and Ballston metro stations. Water is pouring down the stairs at Capital Hill South station, and of course the roads and sidewalks are no better. We are in a flood warning since the ground is already so water-logged from last week. Unfortunately the storms slowed down just as they reached the Beltway, which means we’re getting more rain than we would have if they would have scooted out by now.

A few more storms are possible through the evening, and we’re already seeing signs of that in Loudoun County where another storm is beaming toward Reston.

4:50 p.m. — Flood warning for Beltway, severe t-storm warning southwest of Beltway

Flooding is likely in the heaviest downpours this evening. The ground is still fairly wet from last week’s rain, so it’s not taking much for water to run off and flood low-lying areas. Take this example from Bethesda after the storms moved through. We don’t expect widespread flash flooding, but areas that typically flood first — areas around creeks and streams, underpasses and highways — will probably become waterlogged as these storms move through.

Another severe thunderstorm warning has been issued for the part of this squall line that’s southwest of the Beltway, covering Springfield, Burke and Dale City. Strong winds are the biggest issue here, with gusts approaching 50 mph as estimated on radar.

4:21 p.m. — Storms are in the Beltway

This squall line is booking through the metro. It’s not severe at this point but it does have some heavy downpours and frequent thunder and lightning. If you’re in the District and you want to avoid the downpour, you can probably just wait until it’s over and still be able to leave before 5 p.m.

3:27 p.m. — Severe thunderstorm warning for parts of Montgomery County

A line of storms is already racing toward the metro and has triggered a severe thunderstorm warning for parts of Montgomery County, including Gaithersburg, Germantown and Rockville. Strong wind gusts and quarter-size hail are possible, and we can’t rule out isolated flash flooding along streams and creeks.

Original post:

The evening rush could be stormy for some of us Tuesday as a cold front approaches the region. Conditions really aren’t that favorable for widespread severe thunderstorms, but models have been hinting at the possibility of a squall line this evening, with the highest risk being just south of the Beltway.

The Storm Prediction Center has part of the Washington region in a “slight” risk of severe weather, which means scattered severe storms are possible, although they will probably be short-lived. The main hazard in these storms will be strong wind gusts and heavy rain.

Storm dashboard

• Approximate arrival time for storms
  • 3 p.m. — Interstate 81
  • 3-4 p.m. — Northern Virginia
  • 4-5 p.m. — Fauquier, Prince William, Beltway
  • 5-6 p.m. — East and southeast suburbs
• Storm duration: One to two hours
• Chance of measurable rainfall in any location: 60 to 90 percent from north to south
• Storm motion: Northwest to southeast
• Likely storm effects: Strong winds, downpours, isolated flash flooding, lightning
• Possible storm effects: Small- to medium-size hail
• Very small chance of: Damaging winds, large hail
• Rainfall potential: Up to two inches in the heaviest storms

If clouds thin out this afternoon, we might get enough heating to feed a line of storms later this evening. Clouds are most likely to break up around and south of the Beltway, which is why that region has a higher risk than the northern suburbs.

“It is plausible that a cluster of storms will intensify along the Blue Ridge vicinity this afternoon and spread east-southeastward toward the I-95 corridor by late afternoon/early evening,” the Storm Prediction Center wrote in its Tuesday outlook. “Damaging winds would be the primary hazard.”

Both the high-resolution NAM and the HRRR models expect storms to move through later this afternoon and evening. The HRRR suggests that storms could enter the immediate metro area by 4 p.m.