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Posted at 5:00 AM ET, 07/29/2010

Forecast: Storms today no match for last Sunday's

By David Streit

Seasonable weekend won't seem seasonable!

* A colorful D.C. sunset | Were you caught off-guard Sunday? *
* Outside now? Temps & more: Weather Wall | NatCast *
* # of 90+ days: 43 (Apr: 2; May: 3; Jun: 18; Jul: 20), Record: 67, 1980 *

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


Storms are nobody's friend after Sunday but with some luck they'll miss both am and pm commutes.
Get the 'Digit' on Twitter


Today: Partly cloudy, midday and p.m. t-showers. 91-94. | Tonight: Clearing early. 67-72. | Tomorrow: Sunny, drier. 84-88. | A Look Ahead | Get Express Forecast by E-mail


By David Streit, CWG Meteorologist

The storms today should be fairly benign and they mark the leading edge of one of the driest air masses we have seen in a long time. The break in the heat and humidity make for a great first half of the weekend. Unfortunately, showers (not storms) should return on Sunday so get the outdoor activities in on Friday and Saturday. Below normal temperatures in July have been limited to the first 3 days of the month. Glad to say good bye to July!

Radar & lightning: Latest regional 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 (Thursday): The day is likely to start off mostly sunny and humid. The temperatures will make a quick run up through the 80s as a line of thundershowers approaches from the northwest from midday into the early afternoon. Highs should peak in the lower 90s just about then. The thundershowers (70% probability) will knock readings down to the upper 70s in much of the area. Look for a few wind gusts and brief heavy downpours but damage should be minimal. Best bet is that the skies will begin to clear by late afternoon. Confidence: Medium

Probability: 70%
Coverage: Scattered to widespread
Likely timing: 11 a.m. to 5 p.m.

Tonight: The breezes from the north this evening along with clearing skies are the first signs of drier, milder air starting its invasion. Evening temperatures should be in the upper 70s to lower 80s and slowly decline to the upper 60s to lower 70s overnight. Confidence: Medium

Keep reading for the forecast through Monday....

Tomorrow (Friday): Dawn comes bright and mild. Light winds from the north continue to steadily drop humidity and slow the rise of temperatures with upper 70s to lower 80s by lunchtime. Highs will be near normal for a change in the mid-to-upper 80s. Confidence: High

Tomorrow Night: Temperatures briskly fall through the 70s in the evening as dewpoints in the 50s are a real treat. There is no excuse to not go for an evening stroll! Lows end up in the 60s. Confidence: High


Saturday brings a picture perfect day with humidity still quite comfortable and seasonable temperatures on tap. However, clouds will start appearing from the south and steadily increase so that by evening a mostly cloudy ceiling will be in place. The clouds stop highs from going beyond the mid-80s by early afternoon. It is unlikely that any showers dampen evening activities but there is a 30% chance of raindrops by midnight. Confidence: Medium

Sunday is doomed to be a mostly cloudy day as moisture continues to stream up from the south, raising humidity levels and setting off scattered showers that become more pervasive by midday. Temperatures only edge up slowly from upper 60s to lower 80s. At least 70% of the region should get some decent rain out of this shower event. Confidence: Low-Medium

Monday gets off to a cloudy and humid start. Most of the showers should have pushed eastward to the beaches but a morning sprinkle can't be ruled out. Skies should begin to break by midday allowing highs to get up to seasonable levels in the mid-80s. Confidence: Low-Medium

By David Streit  | July 29, 2010; 5:00 AM ET
Categories:  Forecasts  
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Next: D.C. record snow in 2010 not due to global warming


David - I love your line, "glad to say goodbye to July!" I look forward to a similar line about August in 5 weeks!

Posted by: authorofpoetry | July 29, 2010 8:12 AM | Report abuse

david, CWG,
how does it look for bunch of kids out boating on a lake around 6:30. looks like temps will be perfect by then! how certain are you about the timing of the storms ("early afternoon")?

also, there's something sunday afternoon/evening. i've noticed the "at a glance" keeps getting worse for sunday...

are we back to that crappy everyday afternoon thunderstorm pattern?

Posted by: walter-in-fallschurch | July 29, 2010 8:35 AM | Report abuse

The news this morning said we had 70% humidity, isn't that almost raining?

When folks visiting from AZ are saying "NO MAS!! It's too hot here!" I know we're really, ridiculously, disgustingly hot.

Posted by: wadejg | July 29, 2010 8:55 AM | Report abuse

Walter, just looked at the pace of the line on radar and it looks like the thundershowers should come through between 1 and 2 pm so they should be long gone by 6 pm, so that looks good. As for Sunday, yes it looked bad yesterday and it looks just as bad on the most recent model runs. This will be more of an off and on showery all day kind of event, not a quick passing line of thundershowers like today. However, I don't see us getting into the thundershowers every afternoon kind of pattern anytime soon.

Posted by: davidstreit1 | July 29, 2010 9:24 AM | Report abuse

thanks david. i guess that's good news for tonight, bad for sunday....

re sunday: may i suggest, if there must be rain, and i gather there must, that it be done by, say 5:00pm...earlier if possible?

re sunday: is there more chance of it "speeding up" and being done by 5 pm, or "slowing down" and not starting 'till say, 10 pm? i.e., which should i be praying to the weather gods for?

Posted by: walter-in-fallschurch | July 29, 2010 10:17 AM | Report abuse

Walter, David makes a proper call on this forecast. Sunday will be later than today. Today should mostly finish by 6pm. Sunday may not start till 6pm. It would trend toward sundown and die after the sunsets. That will be the type of airmass behavior at that point on Sunday... and take David's advice to do most of your outdoor plans Friday & Saturday, okay? :)

Posted by: Camden-CapitalWeatherGang | July 29, 2010 10:28 AM | Report abuse

The models have shown little blips into the evening (this is the 8p radar sim). I would not be totally confident we're done mid afternoon though the position of the front makes me wonder why they keep showing this into the eve.

Posted by: Ian-CapitalWeatherGang | July 29, 2010 10:31 AM | Report abuse

Not to disagree with Camden, but this does not look like late Sunday -- 8 am panels from the last two gfs runs: (6z gfs | 0z gfs). Looks like two potential waves, one early, some lull then more later. Then again, around here it's hard to believe a model run 3 days out...

Posted by: Ian-CapitalWeatherGang | July 29, 2010 10:37 AM | Report abuse

great maps there ian. i will choose to believe david re showers being "long gone" by 6 today. in the other hand i choose to believe ian, if i understand properly.

ian, are you saying it might be done by afternoon/evening on sunday? or that we might be in "the lull" at 6pm sunday? i know how that "believe a model run 3 days out" thing goes... usually i believe the model run (because it shows 8" of snow) and am disappointed by the lack thereof... here, i'm rooting against precip...

if this is getting too complicated for you guys, i'll just have clear weather all day sunday and take the rain on monday, please.

Posted by: walter-in-fallschurch | July 29, 2010 11:18 AM | Report abuse

Montgomery County about to be slammed again....when most of them just got their power back too. Somebody up there likes playing cruel jokes.

Posted by: rwalker66 | July 29, 2010 12:21 PM | Report abuse

Need to go to Ballston aoa 3-6 pm--hope this storm is done by then.Don't need it to force me into an UNDESIRED Friday afternoon trip...would like to keep my Friday as FREE as possible...!

Just checked the IAD Skew-T: PW is 2"+, CAPE @ 400-850 j/kg, w. 1500-2000 possible. Total Totals Index (TTI) is 50 w.80%+ chc. of severe storms; other indices also trending towards severe wx. Storms appear to be moving SE from vicinity of Frederick, could be here within 2 hrs.

Posted by: Bombo47jea | July 29, 2010 12:24 PM | Report abuse

walter-in-fallschurch, re: sunday, it seems hard to say when the greatest likelihood of heavier rain is looking at the runs. To me it looks like there is a chance all day, but I'd also probably tend to think it's overdone... but we'll see. re: today... looks like there are still showers around as of 6:15, though the front is knocking on DC's door.

Posted by: Ian-CapitalWeatherGang | July 29, 2010 6:18 PM | Report abuse

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