Comment 5:05 p.m. — Storms extend from Baltimore to McLean, but not severe (latest update) While the storms that followed from Frederick, Md. north of Baltimore were quite intense, damaging trees and power lines (and prompting severe thunderstorm and tornado warnings), the rest of the storm’s activity is generally subdued. Radar shows thunderstorms extending from Baltimore to Silver Spring back to McLean and Chantilly. This activity is also pushing to the east-northeast and should cross the northern half of the Beltway in the next hour to 90 minutes. Showers, lightning and gusty winds possible. This activity should remain mostly subdued, but we cannot rule out an additional isolated strong storm. This will be our last update to the article. Stay tuned for our new PM Update article for a fresh look at the forecast through Tuesday, which will be posted around 6 p.m. 4:30 p.m. — The storm, stretching across eastern Loudoun and Montgomery counties, has weakened some Radar shows storms from Laytonsville (in Montgomery County) through Ashburn and back to The Plains (on the Loudoun-Fauquier County border). There are currently no severe thunderstorm warnings, but the cell over Montgomery County has very heavy rain and frequent lightning. This activity continues to move east-northeast and should be near the northern part of the Beltway beginning shortly before 5 p.m. 3:54 p.m. — Severe Thunderstorm Warning for eastern Loudoun, western Montgomery and northern Fairfax counties Strong to severe thunderstorms have advanced near Leesburg and are moving quickly through the zone that includes Ashburn, Poolesville and, about 4:30 p.m., the Interstate 270 corridor — from Rockville to Germantown. These storms have a history of downing some trees, so head in if you’re in their path. They look near the northern part of the Beltway around 5 p.m. or shortly before. 3:35 p.m. — Strong to severe thunderstorms from Frederick to Front Royal sweeping east-north A fairly strong line of storms has pushed east of Interstate 81 and now stretches from Frederick to Front Royal, both of which are under severe thunderstorm warnings. That activity — which downed trees and power lines near Frederick — is moving east to north faster (about 35 mph) than previously expected. It should reach northern Fauquier, eastern Loudoun and western Montgomery counties within 30 to 60 minutes. It may approach the Beltway around 5pm, maybe a little earlier. It’s warm and muggy and a cold front is approaching the Washington area. These are key ingredients for strong to severe storms that could produce very heavy rain and strong – even damaging – winds. The National Weather Service has issued severe thunderstorm and flash flood watches for the area through this afternoon. Thunderstorms were already developing along and east of Interstate 81 Monday afternoon and are expected to sweep through the Washington area in the late afternoon and early afternoon. Storms may reach the Route 15 corridor from Frederick to Warrenton by 3 or 4 p.m., the Beltway closer to 5 p.m. and in southern Maryland and the Bay Area at 6 or 7 p.m. The storm, which stretches from northern Virginia to western Connecticut, affects 40 million people and ends at 10 p.m. “Storms will intensify this afternoon along a track from Northern Virginia to southeastern New York,” the watch says. “Stronger cells will pose a risk of localized damage from wind gusts.” Remember that a severe storm means that conditions are favorable for severe storms, but not a guarantee. If a severe thunderstorm warning is issued for your location, on the other hand, it means a severe storm is imminent and you should seek shelter immediately. Given the prospect of heavy rain and how wet it has been for the past week or so, the Met Office has also issued a flood watch until midnight. “Afternoon to evening showers and thunderstorms can bring very heavy rainfall which can cause flash flooding. This could include multiple rounds of storms that would increase the risk of flooding,” the Weather Service writes. “Rainfall rates may reach 1 to 2 inches per hour, locally higher in spots. The DC and Baltimore metro areas will be the most sensitive due to the recent heavy rainfall over the past two weeks.” A Flood Watch has been issued for parts of the area from 4pm-midnight. The threat of flash flooding may come with rainfall of 1-2 inches per hour, locally higher in spots. Additionally, some strong to severe thunderstorms will be possible. #MDwx #VAwx #DCwx #WVwx pic.twitter.com/K0ZareqyLL — NWS Baltimore-Washington (@NWS_BaltWash) July 18, 2022 Remember, if you’re traveling late this afternoon, try to avoid routes that are usually flooded, and if you encounter high humidity, turn around, don’t drown. Places most prone to flooding include places near creeks and streams as well as low-lying, poor drainage areas. Also be aware that some storms can be severe, with damaging gusts. Remember, “when it roars, go indoors.” Severe storms with damaging wind threats may tend to focus on areas north and northeast of Washington. Although the atmosphere has destabilized ahead of the cold front and an approaching jet stream disturbance will increase air lift, the strongest wind shear and the potential for widespread severe thunderstorms is over Pennsylvania and New Jersey. Severe cells may be somewhat more isolated further south. The Washington area may be a bit more prone to flooding given the extremely moist atmosphere above, which will produce heavy rain storms. While these cells will be moving, the very wet soils that prevail may present some flash flooding concerns. It’s been a very windy stretch in the Washington area the past couple of weeks. Multiple severe storms and flooding have affected the area. Reagan National Airport has already received 6.57 inches of rain this month, the 21st wettest July on record with nearly two weeks to go. The recurring storm is linked to the fact that the jet stream, along which the storms follow, has steadily flowed through the Mid-Atlantic region. A silver lining of the jet stream design is that it has mostly kept excess heat at bay. The Northeast is enjoying a pleasantly mild summer as the Plains and South bake
