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Posted at 05:00 AM ET, 08/13/2011

Forecast: Heavy showers and storms this afternoon and Sunday

(originally posted at 5 a.m.)

9:45 p.m. UPDATE: Except for the far southern suburbs (south of Prince William county), where showers continue - we should have an extended break from rain until the pre-dawn or early morning hours.

4:00 p.m. UPDATE: Shower and storm coverage has decreased a bit since earlier, but it’s still pretty likely they continue to dot the area for the next few hours at least. A strong to severe storm with damaging wind is also possible.

1:20 p.m. UPDATE: Widespread showers and thunderstorms have developed to the southwest and are moving to the northeast. In short, the remainder of the afternoon looks quite unsettled with intermittent (70-80% chance) showers and thunderstorms which may produce locally heavy rain.

Today's Daily Digit
 
A somewhat subjective rating of the
day's weather, on a scale of 0 to 10.

 
Above average warmth seems to be the norm? We've seen worse, and it shouldn't be too rainy just yet. Lowered 1 since tweet for slightly increased rain threat.
 
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EXPRESS FORECAST

Today: Increasing clouds. Chance of Showers/t’storms likely. Mid-80s to near 90. | Tonight: Mostly cloudy. Showers increasingly likely. Upper 60s to low 70s. | Tomorrow: Periods of showers and t’storms. Heavy rain possible. Near 80 to low 80s. | Get Express Forecast by E-mail

FORECAST IN DETAIL

Least “cool” cooldown ever? Today should continue that trend unless a lot of showers hold us back despite occasional showers and thunderstorms this afternon. Also, have some more humidity thrown in for good measure! Tomorrow may be payback for all the summer warmth and overall dry conditions. While I kind of personally wish it were not going to rain on a weekend, at this point I think we can all (especially those who’ve been dealing with smoke to the south) agree that any rain is good rain.

Today (Saturday): Compared to the last few days there should be a good deal more clouds, but hopefully we squeeze in some periods of lots of sun for anyone hitting the pool or headed to the beach. I can’t really rule out an isolated shower even in the morning, but it seems the most widespread (40% chance) activity holds off ‘til later in the day. There could be a t’storm or two also mixed in. but showers and storms become numerous during the afternoon (70-80% chance) - some with heavy rain. With a return of moisture, highs in the mid-80s to near 90 feel a bit more uncomfortable than Thursday and Friday. Confidence: Medium

Tonight: After what may be a pause following daytime activity, rain chances increase as the night wears on, but we may just make it through the heart of it with nothing more than a few showers and thundershowers. Drifting toward morning, odds of rain go up to about 60%, and some of it could be heavy. Lows are fairly uniform in the upper 60s to low 70s. Confidence: Medium

Keep reading for the forecast through the beginning of next week...

Tomorrow (Sunday): It’s a near certainty that everyone gets at least some rain, which we have not been able to say much of late. There are, however, still questions as to totals. Periods of rain — heavy at times — and storms are likely (80-90% chance), though it probably won’t rain all day. Cloudy skies and precipitation should help keep temperatures in check, and if highs only reach near 80, as expected, it will be the coolest day since at least July 15 (82) or perhaps back to June 20 (80) or June 14 (78). Confidence: Medium

Tomorrow night: Surface low pressure may be slow to slide northeast and periods of rain, potentially moderate to heavy and mixed with thunder, could persist through the night (70% early, 30% by morning). Lows reach the mid-60s to near 70, and the more persistent rain should wind down around sunrise if not a bit before. Confidence: Low-Medium

Precip totals... Similar in ways to a cool-season storm and juiced by summertime moisture, it’s hard to nail down where the heaviest axis of precipitation may setup during the day and then potentially into the night, but whoever gets into it may pick up several inches of rain. Everyone else should strive for the .5-1”+ category, though less is also possible in spots missed by heavier bands of rain.

A LOOK AHEAD

On Monday we’re still under the influence of an area of upper-level low pressure even as the surface low heads northeast. This means we’re probably rather unsettled with numerous clouds, especially during the warmth of the afternoon. There’s a shot (about 30-40%) of a few showers as well. Highs should be subdued by continued cloudcover, reaching the low-to-mid 80s. Confidence: Medium

By Tuesday the upper-level low pressure finally lifts northeast. This means we should see more sun than previous days, but depending on just how far it moves, that could still be sullied by bubbly late-day clouds and a risk of showers. For now I think that both should be minor issues, but I’ll go with a 20% chance of showers during the afternoon. Highs probably inch up at least a bit, say mid-80s most spots. Confidence: Medium-High

By  |  05:00 AM ET, 08/13/2011

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