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Posted at 5:00 AM ET, 08/ 9/2010

Forecast: Another round of record-threatening heat

By Jason Samenow

* 90+ days in 2010: 48 (Apr-May 5, Jun-July-Aug 43); Record: 67 (1980) *
* Interactive sunset map & submit your own | Weather Wall *
* Air quality alert: Code orange today (unhealthy for sensitive groups) *

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

 

As the heat mounts, the digit tumbles. It's bad today, but there's worse to come.
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today:Mostly sunny and hot. 90-95. | Tonight: Partly cloudy and warm. 70-77. | Tomorrow: Partly sunny and very hot. 96-99. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

A record warm spring. A record hot June. A tie for a record hot July. Four record hot days. Five record warm nights. Five heat waves (defined as 3-day periods of 90 or higher). A 12-day consecutive stretch at 90 or higher. Pretty intense stuff. And yet, the record smashing summer of 2010 may keep bringing it -- with at least a couple chances to set more records this week. This 90+ degree weather could stick with us all week with the hottest days Tuesday and Wednesday.

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Today (Monday): Though we're anticipating highs in the low-to-mid 90s, this may actually be one of the more pleasant days of the week. That's because humidity holds in the moderate range. On the other hand, the sun is pretty intense and the breeze is minimal -- so I wouldn't call it refreshing. Confidence: High

Tonight: Muggy and warm conditions overnight with lows in the upper 60s in the cooler suburbs to the mid-to-upper 70s downtown. Confidence: High

Do you agree with 'Digit'? Vote in the Digit box above. And keep reading for the forecast through next weekend...

Tomorrow (Tuesday): This is probably the second hottest day of the week as abundant sunshine boosts temperatures into the upper 90s. The record at Reagan National for the date is 98 (from 1943) and Dulles' record is 97 (from 2001) -- so both of these should be in play. Humidity levels will be uncomfortable (dew points in the mid-to-upper 60s) but just shy of what I'd call oppressive. Once again, a lack of wind means stifling conditions and poor air quality. Confidence: Medium-High

Tomorrow Night: Though there won't be much in the way of cloud cover, we won't get a ton of relief from the heat. Overnight lows only drop into the upper 70s downtown with low 70s in the cooler suburbs. Confidence: Medium-High

A LOOK AHEAD

20100807_2781.jpg
The Georgetown waterfront post-sunset Saturday. By CWG photographer Ian Livingston.

Wednesday is probably the week's hottest day - with highs around 100 degrees around the region. Matching or besting DCA's record high of 101 (from 1900) will be a reach, but not out of the question. Factoring in the humidity, it will probably feel like 105. Maybe, just maybe we see a few storms late in the day (30% chance). Storms may linger into the evening, when it's muggy and warm with lows in the 70s. Confidence: Medium

The core of the heat moves off Thursday and Friday, but the drop off is modest and the humidity holds its ground. Highs Thursday are probably in the mid-90s with low 90s Friday. The proximity of a front to the north may (30% chance) help induce some scattered afternoon and evening thunderstorms. Overnight hours are warm, with lows in the 70s. Confidence: Medium

The pattern for next weekend is not exactly clear. A cold front may push some cooler air into the region or it may stay north as more heat builds back into the region from the south and west. I'll call for something in between with highs around 90 both days with a chance (30%) of p.m. thunderstorms given the proximity of the front. Overnight temps should be in the upper 60s to mid-70s under partly cloudy skies. Confidence: Low

By Jason Samenow  | August 9, 2010; 5:00 AM ET
Categories:  Forecasts  
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Comments

Wednesday night track workout becomes a slow jog again. Oh well.

Posted by: JefffromHuntington | August 9, 2010 7:09 AM | Report abuse

Good morning...

Twitter follower @debiguity writes: "you know it is the last third of the summer when forecasts for 'near 100' just get a shrug." Seems to be the case...

Posted by: Jason-CapitalWeatherGang | August 9, 2010 9:25 AM | Report abuse

I find it a bit of a stretch that a "heat wave" is simply three days of 90+ temperatures. Who's definition is that? 89/90 is the normal high for a lot of the summer here now, and with a typical weather pattern (particularly in summer, when the upper level winds are light) lasting 2, 3, or 4 days, why is that considered a "heat wave" as if it's something abnormal? Do we call it a "cold snap" if the highs don't reach 43 degrees for three straight days in February? I just call it "February" or "August" as the case may be...

Posted by: vtavgjoe | August 9, 2010 9:46 AM | Report abuse

Jason - Agreed! It is now the middle of August so even if we have more of this horrible heat, it cannot last forever, like it felt like it would back in June. That said, are there any long range forecasts offering even a hint of a cool down?

Posted by: authorofpoetry | August 9, 2010 9:55 AM | Report abuse

70 dew point is not "moderate" humidity IMHO. Oh, well.

Posted by: jojo2008 | August 9, 2010 11:25 AM | Report abuse

@jojo2008

Agreed. Was thinking mid-60s but the humidity has overperformed. This has turned into an overly optimistic forecast!

Posted by: CapitalWeatherGang | August 9, 2010 11:57 AM | Report abuse

So I was looking at weather.com and some of the local D.C. newscast weather forecasts. Apparently, they are advertising a cool down by Thursday, through the weekend of temperatures in the upper 70's to mid 80's. Are these forecasts crazy?

Posted by: authorofpoetry | August 9, 2010 11:59 AM | Report abuse

@vtavgjoe

You raise a good point. Though three consecutive days above 90 is one particular definition of heat wave, there is no universal definition --probably because a heat wave in Phoenix (90+ for three days would be a ridiculously low threshold there) is much different than a heat wave in Minneapolis. If you wanted to be scientific about it, you could use a statistical standard deviation.

Posted by: CapitalWeatherGang | August 9, 2010 12:01 PM | Report abuse

Unfortunately the heat comes BEFORE my Wednesday morning departure for Wisconsin--and the seven-day outlooks for Eau Claire are ratcheting up the high temperatures there into the low nineties!

This is still not the most uncomfortable summer I've been through in Washington, however. That was the year...I believe it was 1981...when triple digit temperatures persisted past Labor Day into the first week of September! Extreme heat is hard to take in September when one normally expects it to be cooling off.

Posted by: Bombo47jea | August 9, 2010 1:12 PM | Report abuse

Perhaps I'm thinking of 1980 rather than '81, as that was the year we had 67 90+ degree days.

Posted by: Bombo47jea | August 9, 2010 1:14 PM | Report abuse

@authorofpoetry

Here's the deal with the differing late-week and weekend forecasts that are out there: As Jason alludes to in the weekend forecast above, what we have is a lot of uncertainty, based on different models saying different things, about whether a "backdoor cold front" (cooler air trying to back its way in from the north/northeast, rather than the usual direction from the northwest) will be strong enough to cool us down a lot, somewhat, or not much at all. Confidence should grow in one direction or the other in the next few days.

Posted by: Dan-CapitalWeatherGang | August 9, 2010 1:27 PM | Report abuse

How many virgin chicken sacrifices will it take to get the cooler temps to come true?

Posted by: hereandnow1 | August 9, 2010 1:53 PM | Report abuse

I'm with Hereandnow. We've earned a cool down and it's time for mother nature to pay up.

Posted by: authorofpoetry | August 9, 2010 2:00 PM | Report abuse

The comments to this entry are closed.

 
 
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