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Posted at 5:00 AM ET, 08/ 4/2010

Forecast: 90s return in typical August fashion

By Dan Stillman

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

 

Hot & humid stuff is back. But we've seen plenty worse this summer.
 
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EXPRESS FORECAST

Today: Partly sunny & humid. 30-40% chance of showers/storms. Low-to-mid 90s. | Tonight: 30-40% chance of evening showers/storms. 70s. | Tomorrow: Partly sunny & humid. 50-60% chance of mainly p.m. storms. Mid-to-upper 90s. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

I remember thinking last summer -- during a comfortably warm, but not-too-hot-and-humid June and July -- what if every Washington summer was as nice as that one had been? And then came August. There's a reason August in D.C. has a bad rep. Even in overall cooler-than-average summers like last year's, August still seems to bring the steam (Aug. 2009 finished 2.4 degrees above normal). Despite the cooler first few days of this August, the next few days bring back typical August heat and humidity.


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.

Today (Wednesday): Heat and humidity is back today, with partly sunny skies and highs likely climbing to the low 90s, maybe some mid-90s. A few showers or thunderstorms are possible (30-40% chance for any given location). Most likely times for precipitation appear to be in the early-to-mid morning (thunder not likely) and then again in the late afternoon into evening. Confidence: Medium

Thundercast:
Probability: 30-40%
Coverage: Isolated-Scattered
Most likely timing: 5 p.m. to 11 p.m

Tonight: So many muggy nights this summer and it looks like quite a few left to go, including tonight. Shower/storm chances remain around 30-40% through evening before diminishing overnight. Humidity stays high, and so do low temperatures: low-to-mid 70s in the suburbs and upper 70s downtown, under partly cloudy skies. Confidence: Medium

Keep reading for the forecast through the weekend...

Tomorrow (Thursday): Often we get our warmest days with breezes from the southwest ahead of an approaching cold front. That's the situation we have for tomorrow with highs reaching for the mid-to-upper 90s, high humidity and a 50-60% chance of showers and possibly strong thunderstorms -- primarily from mid-afternoon through mid-evening. Confidence: Medium

Tomorrow Night: The way the timing looks now, the cold front should be past and moving east/southeast away from the area by late evening or around midnight, taking the shower and storm chances with it. In the front's wake, the overnight should bring clearing skies and lows in the low-to-mid 70s. Confidence: Medium

A LOOK AHEAD

Friday shapes up to be a pretty nice one, especially compared to Thursday. Yes, we're still plenty warm with highs probably in the low 90s. But lower humidity and partly to mostly sunny skies should make for one of the more pleasant days we've seen this summer. Alternate scenario?... there is an outside chance (20%) the front hangs around close enough to trigger an isolated afternoon shower. Confidence: Medium-High

Odds are that Friday night remains rain-free. But, depending on how close the front is and whether low pressure develops along it, there's a small chance (20%) we could see isolated to scattered showers. Confidence: Low-Medium

Conflicting model information makes the weekend forecast kind of tricky in terms of temperatures. Best guess? Highs in the mid-80s to near 90 (though low 90s aren't out of the question if the warmer model is on to something) and morning lows in the mid-60s to low 70s. Humidity should be moderate and rain chances fairly slim with partly to mostly sunny skies. Confidence: Medium

By Dan Stillman  | August 4, 2010; 5:00 AM ET
Categories:  Forecasts  
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Comments

Last night's rain in College Park was intense! Heavy downpours and thunder long and loud enough to terrify the dog were NOT expected!

Posted by: kolya02 | August 4, 2010 6:12 AM | Report abuse

Typical??? Typically, we average 87 degrees this time of year.

The only thing "typical" about this weather is that we have been running 10 degrees hotter than normal for several months.

Posted by: AxelDC | August 4, 2010 7:45 AM | Report abuse

Question: radar shows showers moving from NW to SE right now, but the winds are from the S or SW. Are winds at cloud altitude moving in a different direction, or are these showers not driven by wind but something else?

Posted by: mmurphy70 | August 4, 2010 9:26 AM | Report abuse

I always find it hard to believe that August is worse than July when the avg for the month start off at 88 but drop to 83 by the end of the month. But I won't believe for a moment we will see consistently low 80 days until December bases on the patterns this year...followed by 4 ft of snow.

Posted by: hereandnow1 | August 4, 2010 9:26 AM | Report abuse

Dan - you are quite right about last summer - it stayed cool until a few heat waves in August. But statistics still support July being the hottest month for most of the country over August, although not by much. Some will argue August "feels" the hottest due to humidity but we have high humidity in July too, AND higher temperature. It doesn't help after a scorching July people grow tired of the summer.

Posted by: LoudounGeek | August 4, 2010 10:21 AM | Report abuse

@kolya02
Yesterday afternoon's PM Update actually did have a shower/thunderstorm risk in the forecast for last night, though I realize that's no consolation for the dog :)

@AxelDC
Though above average, today's low-to-mid 90s are pretty typical for August and summer in general here -- remember, our averages are primarily the result of streaks of below-average and above-average weather. Of course, this summer we haven't seen much in the way of below-average stretches. If we manage the upper 90s tomorrow, then yes that is a bit less typical but not unusual.

mmurphy70
You're on the right track. The winds at cloud level often blow in a different direction and at a different speed then winds here at the surface. Thus clouds and precip do not necessarily move in the same direction as surface winds.

Posted by: Dan-CapitalWeatherGang | August 4, 2010 10:28 AM | Report abuse

I hear Philly may see the Northern Lights tonight. Any chance we get to?

Posted by: stevensmichaelj | August 4, 2010 12:22 PM | Report abuse

Check the Skew-T diagram annotations for IAD...it has been showing the "Storm Direction" at around 300 to 330 degrees (northwesterly) for quite some time. For general reference, winds are computed in a 360-degree circle starting with "north" at zero degrees, and proceeding clockwise. Thus east is 90 degrees, south is 180 degrees and west is 270 degrees.

Tom Skilling is back on this afternoon...

Posted by: Bombo47jea | August 4, 2010 1:38 PM | Report abuse

Muggy dewpoints in the upper 70s have produced heat indices of 103F downtown, 108F at DCA! Clouds hiding the hot sun don't seem to help...

stevensmichaelj - low chance http://www.swpc.noaa.gov/pmap/gif/pmapN.gif

Posted by: Camden-CapitalWeatherGang | August 4, 2010 2:26 PM | Report abuse

stevensmichaelj - sorry to sound so curt. My comment was truncated. And I basically detailed how last night's solar cloud was bigger than the one arriving over the next couple days. Watch that page I hyperlinked for details. But as for tonight DC has

Posted by: Camden-CapitalWeatherGang | August 4, 2010 2:34 PM | Report abuse

The comments to this entry are closed.

 
 
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