8:55 p.m. update: It has rained so much lately, anytime we get more than a little rain, flooding seems to pop up. Some of that is ongoing in parts of Fairfax and Prince William counties, as well as parts of the city of Manassas. If you can stay in tonight, it’s not a bad idea. And remember not to enter water-covered roadways, especially at night.
Flash Flood Warning including Sudley VA, Manassas Park VA, Gainesville VA until 11:45 PM EDT pic.twitter.com/NyLfOpXQ55
— NWS DC/Baltimore (@NWS_BaltWash) August 12, 2017
8:40 p.m. update: It looks like the long-lived supercell thunderstorm that tracked from west of our area into the I-95 corridor is finally dissipating.
At the time of update, there were no severe thunderstorm warnings active, for the first time in a number of hours. It’s not impossible that the core of this storm — now due south of D.C. and meandering east — will see another severe thunderstorm warning issued for it. That said, as we get farther past sunset, storms tend to die off overall. A large area of rain with some embedded thunder continues across much of the area. That may be the case for a while yet. There is some hope that once this cell gets out of the way to our south, a break in the action can move into the immediate area late this evening. Periodic rain continues overnight.
Original post… Scroll to bottom for earlier updates…
Clouds helped keep us cool today, with highs mainly rising to within a few degrees of 80. Those clouds are hinting at some rain to come. That rain will last into Saturday, but we should still salvage part of the weekend at least.
Through tonight: A couple of showers dotted the area this afternoon, and a few storms have recently fired up to the west. It doesn’t feel super stormy out there, but it is very humid, and surface winds are pumping in moisture out of the southeast. With stronger winds aloft, various ingredients are aiding development of a bigger storm or two. While it’s hit-or-miss overall, any storm could become strong to severe. Hail, strong winds and even a quick tornado are all possible in any severe weather. This activity tends not to be widespread or long-lasting enough for major flooding concerns, yet some isolated flash flooding can’t be ruled out in any spot that gets particularly hard hit. It won’t rain all night, but we’ll keep the risk of occasional showers and perhaps a rumble going through most of it. Lows end up in the upper 60s and lower 70s.
View the current weather conditions at The Washington Post.
Tomorrow (Saturday): Rain threatens off and on for much of the day, but I think it’s focused early and late. The early stuff could be more widespread, but it should be relatively pain free, unless maybe if you have outdoor plans. Much of the midday into afternoon could end up dry, with a second risk of rain picking up by afternoon into evening, when a few storms may fire as a front approaches. With all the clouds and some rain, highs probably don’t get too far into the 80s.
Sunday: Coming off lows in the 60s most spots, drier air takes over on Sunday. We’ll be behind the cold front, so skies will be clearer as well, with partly to mostly sunny conditions expected. Highs are in the low-and-mid 80s.
Pollen update: Mold spores are low/moderate. Other allergens are low.
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Prior storm updates…
7:40 p.m. update: Our energizer thunderstorm keep on going. A new severe thunderstorm warning is up for regions out ahead of the storm, until 8:45 p.m. Large hail and damaging winds continue to be the main risks, but there is still some potential a tornado could try to spin up. The focus looks to remain near the southern Beltway and south, although rain and thunder is also falling in the city.
7:00 p.m. update: The one big storm in the region keeps chugging on to the east along the I-66 corridor. In the last half hour it has reorganized to the south a bit farther. A new area of concern may be developing near Nokesville and south of Manassas. In the meantime, another severe thunderstorm warning is up ahead of this thing until 7:45 p.m.
Severe Thunderstorm Warning including Dale City VA, Lake Ridge VA, Manassas VA until 7:45 PM EDT pic.twitter.com/snBbfZ3gIe
— NWS DC/Baltimore (@NWS_BaltWash) August 11, 2017
A view of the storm from earlier shows some typical features of a powerful supercell.
6:25 p.m. update: The storm that was tornado warned continues to move east. It is likely putting down some large hail in the I-66 area. A severe thunderstorm warning has been issued out ahead of it for parts of Fauquier and Prince William counties until 7:00 p.m.
Severe Thunderstorm Warning including Linton Hall VA, Gainesville VA, New Baltimore VA until 7:00 PM EDT pic.twitter.com/gxjTYNfhOz
— NWS DC/Baltimore (@NWS_BaltWash) August 11, 2017
6:05 p.m. update: A supercell thunderstorm has entered into western parts of the area. A tornado warning has been issued for parts of Fauquier and Prince William counties until 6:30 p.m. Seek shelter in these areas.