PM Update: Heavy, potentially flooding rain likely into Friday morning

Flash flood watch into Friday morning | Flood warning for Arlington Fairfax, Prince William and Stafford counties *

11:00 p.m. update: Doppler radar suggests 1-3 inches of rain has already fallen in a narrow strip between Dale City and Germantown, with the higher end (2-3″) amounts focused on the southern half of the strip from roughly Fairfax to Dale City. Meanwhile, there is a sharp cutoff in the rain just to the east of downtown Washington where very little rain has fallen. Over the next several hours the axis of heavy rain will only very gradually shift east and that’s why models have – for several days – suggested the highest rain totals would be west of I-95. Having said that, models show the heart of the metro region – including our eastern suburbs getting slammed by heavy rain between 4 and 10 a.m.

The morning rush may well be very tricky with the possibility of ponding water on roads and even road closures where streams and creeks overflow their banks. Be sure to check in with us in the morning.

10:15 p.m. update: A flood warning has been issued for urban areas and small streams in Arlington, Faifax, Prince William and Stafford counties until 1 a.m. This includes the city of Falls Church and Fairfax. Between two and three inches of rain has fallen in some areas, and an additional two to three inches is possible.

9:00 p.m. update: The main rain event is just now getting started. A very heavy wave of rain is lifting up I-95, currently passing through Dale City. This has its eyes set on the District and its western suburbs over the next hour. Note: Whereas the text below says the heaviest rain may end by 8 a.m. tomorrow morning, some new data suggests heavy rain could continue through mid-to-late morning. It does not look like a nice AM commute…for any part of it right now.

8:00 p.m. update: The scattered thunderstorms that paraded through D.C.’s western suburbs from south to north have mostly exited the region. Now we await a large area of steady rain with some embedded thunder to our south and southwest. This should move into the immediate metro region west of I-95 over the next 1-2 hours and eventually envelop the entire region between 10 p.m. and midnight. Note: the severe thunderstorm watch (in effect earlier west of I-95) has been lifted.


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.

From 5:37 p.m.: Individual thunderstorms and waves of rain cycle through the region tonight into Friday morning, with the potential to cause flooding of low-lying areas, creeks, and streams.  2-4 inches of rain are likely along and west of I-95, with 1-3 inches east of I-95 in the metro region.  The rain ends around midday, with partial clearing during the afternoon.

Through Tonight: Heavy rains – with embedded thunderstorms – are expected in our western and southwestern areas this evening.  Ahead of this main batch of rain along and just west of the I-95 corridor, numerous individual thunderstorms are likely to develop with very heavy rain and possibly some damaging wind gusts.   Eventually, the the area of steadier, heavy rain to the west overtakes the entire area late this evening (after 10 p.m.) and overnight.  Temperatures fall from the 70s back into the mid-60s for lows.  Winds from the southeast at 10-15 mph, gusting to 25 mph (and higher potentially in thunderstorms).

More details on flood potential, rain amounts: Torrential rain likely this evening into Friday morning, significant flooding threat

Tomorrow (Friday): Rain, and possibly a thunderstorm in the morning.  The best chance of heavy rain is early on.  After 8 a.m., the rain turns more showery and intermittent.  The rain should end completely by midday or early afternoon, with partial clearing mid-to-late afternoon (except a 20 percent chance of a shower east of I-95).  It’s not as warm, with highs 70-75.  Winds become from the northwest at 10-15 mph.

See David Streit’s forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter . For related traffic news, check out Dr. Gridlock.

Stormy skies looking from Fairfax out towards Dulles this evening (Chris McNulty via Twitter)

Stormy skies looking from western Fairfax out towards Dulles this evening (Chris McNulty via Twitter)

Pollen: Washed out due to rain/moisture.

Miami tornado/waterspout: The same weather system sending moisture surging up the East Coast is spinning up rotating thunderstorms in South Florida.  Late this afternoon a tornado and waterspout were observed in the vicinity of Miami.  I have not seen reports of major damage.  Here are some pictures:

The storms have also caused flooding.

Also on Capital Weather Gang

Torrential rain likely this evening into Friday morning, significant flooding threat