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Posted at 10:30 AM ET, 08/11/2009

Forecast: Wave Bye to Heat; Cooling at Midweek

By Matt Rogers

* New! Get CWG's Express Forecast by E-mail: Sign Me Up *
* Heat Wave: Live Chat Transcript | Photos | Think Snow *
* Later: Climate Change & National Security: A Tough Sell *


Today: Partly sunny skies. 88-95. 40% chance of t'storms. Tonight: Partly to mostly cloudy with 30% chance of t'storms. 72-77. | Tomorrow: Partly cloudy. 30% chance of mainly p.m. showers/t'storms. 83-88. | A Look Ahead


Hot weather has been quite elusive this summer so that even when we see it, it does not last all that long. After building quickly to our hottest day of the year yesterday (so far), we should see a downward trend in temperatures for the balance of this week. A cold front will move through the area this afternoon and it will be shifting winds, offering thunderstorms, and leading the way to the cooler side.

Temperatures: Current area temperatures. Powered by Weather Bonk. Map by Google. Hover over and click icons for more info. Click and hold on map to pan. Refresh page to update. See map bigger on our Weather Wall.

Today (Tuesday): Look for a mixture of clouds and sun today with a 40% opportunity for showers and thunderstorms. The best chance appears to be in the afternoon time frame as the cold front closes into the area. Temperatures have a broad range around the area from the upper 80s to the mid-90s. This reflects the uncertainty in the timing of cloud cover and afternoon thunderstorms. Confidence: Medium

Tonight: Partly cloudy skies with yet a 30% chance of mainly evening storms (that cold front does not want to move too fast!). Look for lows to mainly hold in the low-to-mid 70s. Confidence: Medium-High

Keep reading for the forecast through the weekend...

Tomorrow (Wednesday): Cooler weather will be arriving into the area and temperatures will only reach up into the mid-80s (a few upper 80s are possible). We will still see plenty of cloud cover and a 30% chance of scattered storms, particularly in the afternoon hours. Confidence: Medium

Tomorrow Night: Partly to mostly cloudy skies will continue. Look for temperatures to slip lower again with 60s in the suburbs to around 70 degrees downtown by the early morning hours. A slight chance for a shower or storm will linger. Confidence: Medium


Thursday is quite tricky at the moment as a disturbance traveling along the cold front to our south could reach far enough north into the area. If true, then we could be talking about a very wet, unsettled day. However, the best thinking for now is that this wet weather-maker will stay far enough south to only offer clouds and cooler temperatures (highs in the upper 70s to low 80s). Confidence: Low

Friday looks to be a partly cloudy day overall with highs in the 80s and a 30% chance of afternoon and evening showers and thunderstorms. Look for morning lows to range from the 60s to around 70. Confidence: Low-Medium

The weekendis shaping up to look like partly sunny conditions with highs in the 80s with lows in the 60s to low 70s. We run the daily risk (30%) of scattered showers and thunderstorms. For a summer weekend in the middle of August, getting near normal temperatures is a good thing! Confidence: Low-Medium

A quick peek at next week shows more humidity, more thunderstorms, and temperatures maybe sneaking back into the 90s at times, but not at the levels seen yesterday.

By Matt Rogers  | August 11, 2009; 10:30 AM ET
Categories:  Forecasts  
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Next: Climate Change & National Security: A Tough Sell


Okay, CWG, I'm getting married on August 22nd in DC, and we're banking on good weather to have our ceremony outside. I know it's still far-out, weather-wise, but any early indication on next weekend?

Posted by: zim94 | August 11, 2009 7:56 AM | Report abuse

West Springfield got hit head on last night and received 0.50 inches. Fun lightning.

Posted by: bikerjohn | August 11, 2009 8:37 AM | Report abuse

Hey Matt, you say yesterday was highest "so far", which is true, but makes me think you could see it being topped this year -- which I find somewhat unlikely.

You're one of my favorite long-rangers... see anything like this heat on the horizon? Seems like we have 2 or 3 weeks at best to push those levels.

Posted by: Ian-CapitalWeatherGang | August 11, 2009 8:56 AM | Report abuse


It's still a little early for us to project that far out. There's isn't much skill in forecasting until within about 5-7 days.

Check back with us Sunday or Monday.

Posted by: CapitalWeatherGang | August 11, 2009 9:21 AM | Report abuse

Hey Ian, right now, I don't see any repeats of yesterday's heat for us through the next two weeks. However, it IS still August and we will have to watch for any quick pop-ups...if it happens, it would be a single day event like yesterday. -Matt

Posted by: MattRogers | August 11, 2009 10:25 AM | Report abuse

Hey Zim94, I'll take a stab at it but this isn't official CWG: Highs in the 80s with a 30% chance of pm/eve t-storms. -Matt

Posted by: MattRogers | August 11, 2009 10:27 AM | Report abuse

"There's isn't much skill in forecasting until within about 5-7 days."

Excepting of course any forecast from Al Gore.

Just kidding, I don't mean or want to provoke another endless debate of that topic.

Posted by: ubimea | August 11, 2009 11:34 AM | Report abuse

Posted by: CapitalClimate | August 11, 2009 1:10 PM | Report abuse

Current temp. in Burke: 92.5 with partly cloudy skies.

This would be a really interesting (and exciting!) scenario for this area:

Posted by: Yellowboy | August 11, 2009 1:23 PM | Report abuse

Yes, Yellowboy, the GFS has been causing trouble with a possible tropical system about two weeks away. That model is notorious for inaccurate storm tracks that far in advance and this particular storm hasn't even formed yet (it's the wave behind TD2). So definitely interesting, but confidence (and likelihood) on such a potential this early is always super low. -Matt

Posted by: MattRogers | August 11, 2009 1:30 PM | Report abuse

"upper 80s to the mid-90s":
Isn't a 10-degree range (87-96) just a tad wide in a less-than-12-hour forecast? Given that 87 is the normal and it's never been higher than 96 at Dulles on Aug. 11 since 1963, this is tantamount to a forecast of "above normal", which has not much more information content than a flip of a coin.

Posted by: CapitalClimate | August 11, 2009 2:43 PM | Report abuse

FWIW, National has been 87 or higher on 48% of Aug. 11s since 1929, and only 2 of those were above 96.

Posted by: CapitalClimate | August 11, 2009 2:57 PM | Report abuse


Today's highs: 93 at National, 92 at Dulles, 89 at BWI. Seems like "Upper 80s to mid-90s," or "88-95" as mentioned in the Express forecast, captured the day's temperatures quite well.

Posted by: Dan-CapitalWeatherGang | August 11, 2009 5:37 PM | Report abuse

And a forecast for the rest of the month of "highs in the 70s to the 90s" would capture nearly all of the days' temperatures as well. Exactly how did the referenced forecast show any skill over climatology?

Posted by: CapitalClimate | August 12, 2009 10:19 PM | Report abuse

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