D.C. area forecast: Rain, flooding risks into midday; nice weather payback this weekend

May 16

Flood warnings for entire area west of central Prince George’s County (see NWS for specific warning info) | Road flooding reports from Dr. Gridlock | Storm/flooding news updates *

9:50 a.m. update: Other than a few scattered showers east of I-95, rain has mostly cleared the area.  However, residual flooding is still occurring as streams crest – so some adjacent roads will still be affected by flood waters for the next several hours until waters begin to recede.  River flooding may be an issue into tomorrow for the Potomac and larger tributaries.  This is our last update…  For the full forecast through the weekend scroll down towards the bottom of this post.  Our next update will round-up rainfall totals and pictures at around 10:30 a.m.

 

9:20 a.m. update: The heaviest rain is pushing east of the bay now, with just some light rain from D.C. and to the east. This activity will continue to taper off over the coming period.  It’s a cool one out there, with temperatures largely in the mid-50s right now.  However, some sun should try to work into the area soon from the west.


(NASA)

9:00 a.m. update: The flash flood watch has been canceled for the local area as rain begins to shift east. The worst is certainly over, but fairly widespread flooding will remain a risk for the next few hours at the least, with rivers continuing to rise thereafter.

8:35 a.m. update: A look at local radar shows (as noted below) that spots to the west of D.C. are pretty much rain free.  The rest of the local area may begin to see things taper off in the next 30-60 minutes as a drier patch works up from the south.


D.C. area radar at 8:35 a.m. (Gibson Ridge)

Lots of trees are down across the area thanks to saturated grounds and some wind with the frontal passage, and flooding remains a major issue at least in spots.

8:10 a.m. update: When’s this going to end? If you’re west of D.C. it’s basically over other than some lighter drizzle or a passing shower. D.C. and east is still receiving moderate to heavy rain. While the whole band is indeed pushing east, it’s a slow process with the rain itself in the band heading north as the line trickles east.  Both radar and short-term modeling suggest it should taper off in the whole area between 10 a.m. and noon, as seen in radar simulations below.  Rainfall rates could still approach 0.50″-1″ an hour in the heaviest east of the city.


RAP simulated radat at 10 a.m. (Weatherbell.com)

HRRR simulated radat at 10 a.m. (Weatherbell.com)

7:45 a.m. update: The heaviest rain is thankfully beginning to push east of the city, but flooding is ongoing in many places this morning.  Here’s a quick roundup of pictures from the 7 o’clock hour:


Fox Mill and Waples Mill roads in Oakton, Virginia. (Kevin Ambrose)

7:25 a.m. update: Rainfall totals between 2-4″ are quite common across the area so far, according to reports in to the NWS through early this morning. Some high totals include 4.25″ at Purcelville and 3.56″ near Manassas. At the local airports, D.C. (National) has picked up 1.91″ since rain began, and Dulles 3.88″.  An incredible 1.11″ of the rain at National Airport came from 6-7 a.m.!

7:10 a.m. update: Flash Flood Warning for immediate metro area including District, eastern Fairfax, southeast Montgomery and Arlington counties, Falls Church,  Alexandria and Fairfax until 10:15 a.m. due to up to 3 inches of rain that has fallen .NWS cautions: “Streams are rising extremely rapidly”  Use caution out there…especially for the next hour or so.  Do not drive through flooded roads.

7:00 a.m. update: Although there is light at the end of the tunnel in terms of the rain ending soon (see 6:45 a.m. update below), it’s still a mess out there with reports of ponding on roads, flooded roads, etc.  Even west of the Beltway where the rain has let up, use caution and don’t attempt to drive through flooded roads.  Some reports:

6:45 a.m. update: Despite the torrential rain, flooding, water rescues, etc., some good news: this storm is going to move out faster than expected.  The worst is already over west of the Beltway. Locations inside the Beltway have another 20-45  30-60 (updated based on slower progress of rain) minutes of heavy rain (west to east).  East of I-95, it will probably take until between 8:30 and 9 a.m. for  the heavy rain to clear.  The front has passed the District and temperatures have dropped some 15-20 degrees.

6:30 a.m. update: The Beltway area continues to get pounded by very heavy rain and some strong wind gusts, but the back edge continues to push east and is now into western Fairfax County.  Rainfall totals through 6 a.m. are remarkably variable.  2.99 inches at Dulles, 0.98 inches at Reagan National and just 0.29 inches at BWI.  But for Reagan National and BWI airports, very heavy rainfall rates between 6-8 p.m. will push their totals into the 1-2.5″ range I expect.

6:15 a.m. update: While conditions are hazardous right now (travel not recommended) due to extreme rains and strong winds, the back edge of the heavy rain has already passed through Loudoun County.  Between 7 and 7:30 a.m., the heaviest rain should be pushing east of I-95.  So the worst conditions in the immediate metro area (inside the Beltway) will be over the next hour or so, then gradual improvement.  It may take until between 8 and 9 a.m. for the eastern suburbs to notice improvement.

6:05 a.m. update: With the torrential rain (several inch per hour rates) and high winds (gusts to 40 mph or so), it is very hazardous out there. There are now multiple reports of cars stuck in flood waters in Fairfax County and Montgomery County and water rescues. If possible, don’t commute right now… delay commuting for at least another 30 minutes.

5:50 a.m. update: NBC4 reports Rock Creek is starting to flood and Beach Drive is closed.

5:45 a.m. update: Torrential rain in area is accompanied by some lightning and thunder and gusty winds. The National Weather Service says gusts to 40-50 mph are possible. “STORM INTENSITY IS INCREASING…AND SEVERE WEATHER MAY DEVELOP RAPIDLY.” The strong winds coupled with the wet ground may make trees vulnerable. Also, ponding of water on roads is likely from the rainfall rates of up to several inches per hour. Be extremely careful out there.

5:35 a.m.. update: Extremely heavy rain is pushing through the immediate metro area and flood warnings cover the entire metro area west of central Prince George’s County.

Today’s Daily Digit

A somewhat subjective rating of the day’s weather, on a scale of 0 to 10.

5
Looks pretty wet into midday, some flooding too. Not what we need. Drier and maybe clearer afternoon.

Express Forecast

Today: Morning downpours, clearing late. Highs: Around 70 to mid-70s.

Tonight: Clearer but a shower possible. Lows: Low-to-mid 50s.

Tomorrow: Sunnier, slightly breezy. Highs: Upper 60s to mid-70s.

Sunday: Fairly sunny, some periodic clouds midday. Shower? Highs: Near 70 to mid-70s.

FORECAST IN DETAIL

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.

Some more unpleasant times until a super nice string of days. We just have to watch for additional flooding with some downpours this morning. Remember, “turn around, don’t drown” — never drive across flooded roads. Luckily, the rain is focused on the morning and we might eke out a decent evening. Just be patient and take it slow while it’s raining. We get to dry out and even enjoy some sunshine in the upcoming days. It is our payback!

Today (Friday): Rain chances, and possibly a thunderstorm, have the heaviest potential in the morning. It appears as if the back edge of consistent rains pushes through in the hours around lunch, but maybe only after depositing ANOTHER 1-2″+ on the area after early-risers wake up. Some spots could near half a foot when said and done?  The good news is we might see breaks in the clouds late. I hope so. High temperatures only get to around 70, perhaps a few mid-70s south of town. Northwest winds in the afternoon should feel refreshing (slowly reducing mugginess) at 10-15 mph, but they could gust above 20 mph at times. Confidence: Medium

Tonight: Those northwest breezes slowly calm below 10 mph after sunset as skies clear out for the most part. I can’t rule out a 15% chance of a shower before 2 or 3 a.m., though. The lower humidity levels feel good, no? Temperatures before dawn bottom out in the low-to-mid 50s. Confidence: Medium-High

For related traffic news, check out Dr. Gridlock. Keep reading for the forecast through the weekend…

Tomorrow (Saturday): Looking much better. Mostly sunny skies dominate for a while, but with cold air aloft we could see our sun self-destruct (generate clouds by warming and percolating surface air upwards into the cold aloft) at times. 10% chance of a shower too? High temperatures, I am happy to report, can’t get much higher than upper 60s north of town, with perhaps mid-70s south of town. Not to editorialize, but I think many should find this comfortable. Westerly breezes around 10 mph should feel great with the sunshine (sunscreen!) and low humidity. Confidence: Medium-High

Tomorrow night: A few clouds could meander their way overhead. But, with luck, you can still view Mercury and Jupiter fairly low on the western horizon by 9 p.m. Overnight low temperatures may cool to the upper 40s outside the Beltway, with low 50s probable downtown. Light westerly breezes may blow at times. Confidence: Medium

Sunday: Could be nearly as pleasant as Saturday, with still some afternoon clouds. Hopefully fewer though, I believe. High temperatures should get near 70 for all, perhaps again some mid-70s possible south of town. Breezes should remain light. We may run a very slight risk of a daytime shower thanks to that lingering cold air aloft.  Confidence: Medium

A LOOK AHEAD

Sunday night: Partly cloudy conditions shouldn’t bother us too much. Rain chances remain low. Low temperatures in the mid-40s are possible in the coolest spots, with temperatures perhaps as mild as the low 50s downtown. Confidence: Medium-High

Monday’s weather might beg for calling in sick to work. It’s looking sunny for the most part (we still may see those periodic clouds, especially midday). Yet it appears rain chances remain very low. High temperatures again hover in our preferred range–lovely broken record style–of the upper 60s to mid-70s. Confidence: Medium

Tuesday’s conditions appear to be leading us to another gem. Mostly sunny skies, presumably with fewer midday clouds popping up, means we easily get above 70 degrees and even mid-70s seem most likely. I wouldn’t rule out a few 80 degree readings nearer Fredericksburg? We’ll see. Confidence: Low-Medium

This post was prepared overnight.

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