D.C. area forecast: Storms bring flash flood potential today; Arthur brushes beaches tomorrow

Flash Flood Watch from 1pm through late tonight.

Today’s Daily Digit

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

3
Increasing clouds take edge off heat, but humidity and a threat of t’storm-induced flash flooding make this rating generous.

Express Forecast

Today: Very humid with strong p.m. t-storms likely. Highs: 88-92.

Tonight: T-storms ending after midnight. Lows: 66-71.

Tomorrow: Breezy, less humid, gradual clearing. Highs: 81-85.

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.

After yesterday’s oven-setting of broil, today is more like slow bake thanks to an increase in cloud population. Humidity remains high enough to make you feel like you are swimming in it. Then there are the thunderstorms. Given the slowed progression of the cold front due to Arthur coming up from the south and buckets of moisture available, localized flash flooding is a risk; most likely in the late afternoon. On the bright side, Arthur passes well out to sea sparing the Maryland and Delaware beaches from significant damage tomorrow. As Arthur exits, so does the heat and humidity, keeping our string of luck going with another stellar summer weekend. storm threat

Today (Thursday): There could still be some sunshine in the morning but clouds are likely to start building by midday. Hopefully, that slows up the warming enough to keep us closer to 90 rather than threatening to hit 100 again. The humidity remains at tropical levels despite Arthur being far to our south. A significant cold front slowly pushes toward the area but the approach of Arthur is likely to slow that advance. This slow movement and buckets of moisture raises the potential for thunderstorms (90% chance) which could produce flash flooding. Strong damaging winds are also possible in the stronger storms. Outside of the storms, winds are only 5-15 mph from the southwest.  Confidence: High

Tonight: Thunderstorm potential continues to be likely through the evening (80% chance) keeping flash flooding threats in place. However, the shower activity should steadily diminish so that by after midnight most areas should be free and clear of rain. Breezes switch to the north behind the front but are only 5-15 mph overnight. Lows range from mid-60s north and west to near 70 downtown. Confidence: Medium For related traffic news, check out Dr. Gridlock.

Keep reading for the forecast through the weekend…

 

 

Independence Day (Friday): Despite the advance of Arthur up the coast, our weather conditions improve markedly. Winds build from the north as they feed into the storm but should not be worse than 15-25 mph given the northeasterly trajectory keeping it far from land. This is good news for all the beach-goers who should only suffer one day of strong winds and high surf. Humidity levels drop notably and despite clearing skies, temperatures only top out in the mid-80s which is a real treat after the last couple of days. Confidence: Medium

Tomorrow night: The only fireworks will be of the man-made variety as Arthur is speeding away from the region and this allows winds to begin diminishing enough that the festivities on the National Mall should be able to proceed as planned. Skies are mainly clear and evening readings are very comfortably ensconced in the 70s. Lows end up in the mid-50s burbs to near 60 downtown, almost chilly! Confidence: Medium-High

A LOOK AHEAD

Saturday will be as “Chamber of Commerce” kind of day with bright blue skies and unimpeded sunshine but most notable low humidity. Highs still reach the mid-80s making it just fine for the pool and beach denizens. The half moon shines next to Mars overhead in the evening sky and readings are again in the 70s. Overnight lows fall to the upper 50s to mid-60s. Confidence: High

Sunday is still a fine summer day but humidity starts creeping up to moderate levels and highs are mainly in the upper 80s. The abundant sunshine it is still hard to complain about, especially for all of those coming back from the beaches or mountains or wherever. Overnight lows should hold in the upper 60s to lower 70s. Confidence: High

Monday features summer misery coming back right on cue for another scorcher. However, as with all of these recent events it should only last 2-3 days. Humidity climbs to uncomfortable heights and highs top out in the low-to-mid 90s. Confidence: Medium

Beach Weather gets off to an iffy start Friday as Arthur may get just close enough to spread showers into the MD/DE/NJ beaches.  The better likelihood of rain, which could be heavy for a time, is down in Southeast Va. Winds range from 15-30 mph in the northern beach areas (MD/DE/NJ) but could be 25-45 mph in the south (VA). However, Saturday and Sunday make up for it with subsiding surf, sunny skies and highs in the mid-to-upper 80s.

Also on Capital Weather Gang

PM Update: Storms round out D.C.'s hottest day of 2014 (so far), more likely tomorrow