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Posted at 9:45 AM ET, 09/23/2009

Forecast: First Full Day of Fall Kind of Summery

By Dan Stillman

More autumn-like conditions arrive by Friday

* NatCast | Classic D.C. Sunrise | Outside Now? Weather Wall *
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EXPRESS FORECAST

Today: Partly to mostly cloudy & humid. A few showers or a t-storm (30-40% chance). Low-to-mid 80s. | Tonight: Partly to mostly cloudy. Slight shower chance. Mid-60s to near 70. | Tomorrow: Partly cloudy. Spotty shower or thunderstorm. Mid-80s. | A Look Ahead

FORECAST IN DETAIL

Blue skies mixed with puffy fair-weather clouds, refreshingly cool air and low humidity. Throw in falling leaves and relaxing background music (I'm sure the Weather Channel has an appropriate tune) and you've got what every first full day of fall ought to be. Right? Oh, wait a sec. Hold on. Kill the music... Autumn officially arrived yesterday, but we stay rather warm with summer-like humidity into tomorrow. Come Friday, though, the weather should be worthy of cranking up that fall theme song.


Radar: Latest D.C. area radar loop shows movement of precipitation over past two hours. Powered by HAMweather. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Today (Wednesday): Today's look and feel should be quite similar to yesterday's, with mostly cloudy skies and temperatures rising from mild morning lows, in the mid-60s to near 70, to afternoon highs in the low 80s, perhaps mid-80s with enough sun. High humidity will make the air seem ripe for rain, but just a few passing showers or a t-storm may be all we get (30-40% chance you get wet where you happen to be). Confidence: Medium

Tonight: Shower chances become slim this evening and overnight. We'll keep that muggy feeling with partly to mostly cloudy skies and lows again in the mid-60s to near 70. Confidence: Medium

Keep reading for the forecast through the weekend. Check back this afternoon for our latest forecast in PM Update....

Tomorrow (Thursday): Could see a spotty shower or thunderstorm as a cold front works its way through the area. Unless the front arrives earlier than currently expected, we're looking at another fairly humid day as we hang on to partly cloudy skies and highs head for the mid-80s. Confidence: Medium

Tomorrow Night: The chance of a shower could continue into evening depending on the timing of that cold front. But eventually we're likely to see clearing skies as a breeze from the north brings in cooler and drier air. Lows in the upper 50s to low 60s. Confidence: Medium

A LOOK AHEAD

Now this is what fall is supposed to feel like: Friday brings partly to mostly sunny skies, low humidity, a refreshing breeze from the north/northeast, and highs in the 70s. Partly cloudy and cool Friday night with lows in the 50s. Confidence: Medium-High

The glorious Friday weather may not last long, with the latest data indicating increasing clouds and increasing chances of rain Saturday and Saturday night as a storm system advances from the west. High temperatures could be anywhere from the upper 60s to mid-70s depending on how early or late in the day clouds and rain arrive. Confidence: Low-Medium

Exactly how quickly our weekend storm will depart isn't clear yet. As of now, I'd say the general timing looks to be a continuing chance of rain early Sunday with partial clearing as the day goes on and highs in the 70s, maybe near 80 if the sun comes out early enough in the day. Confidence: Low

By Dan Stillman  | September 23, 2009; 9:45 AM ET
Categories:  Forecasts  
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Comments

I was planning on going camping in Shenandoah National Park on Saturday night--will the rain from the west be that far south?

Posted by: runningrat11 | September 23, 2009 7:53 AM | Report abuse

CWG,

My daughter's first birthday party will be Saturday afternoon (outdoors) in the Upper Marlboro, Md area. What are the chances of the rain holding off until sunset?

Posted by: suntan | September 23, 2009 8:43 AM | Report abuse

kind of humid out this morning, not very fall-like...

Posted by: madisondc | September 23, 2009 8:53 AM | Report abuse

madisondc, I agree. I stepped off the bus in sunshine this morning and almost thought it was still August.

Posted by: Ian-CapitalWeatherGang | September 23, 2009 10:16 AM | Report abuse

@suntan

How exciting!... my son's second is coming up soon. I know how stressful planning a kid's b-day party can be, even without the threat of weather. Being on the east side of the city in Upper Marlboro helps your chances of staying relatively dry later into the day (the precipitation will be coming from the west). But it's just too soon to say anything with much confidence about the timing. There is certainly a legitimate chance that some rain will get into the area by afternoon, so I'd advise having a plan B in mind, and of course checking back for the latest forecast over the next few days.

Posted by: Dan-CapitalWeatherGang | September 23, 2009 11:23 AM | Report abuse

@runningrat11

Looks wet from Saturday morning through midnight (Sunday) or so at the moment for the Shenandoah mtns but the timing could change.

@suntan

Saturday afternoon looks pretty wet at the moment, but keep checking back.

Posted by: CapitalWeatherGang | September 23, 2009 11:29 AM | Report abuse

The forecasts the last several days have been way off the mark. Last weekend, when the Canadian High came in Friday/Saturday with the really nice cool, dry air mass, it was supposed slide off the coast last Sunday night and to allow a stagnant low-pressure system that was flooding the southeast to mone northeastward behind it. That never happened.......the high moved off the coast as forecast, but the low moved northward instead, west of the mountains, and the rain never got east of the Blue Ridge. Every day, since then, the forecast has been for clouds and showers, but the cloud cover has been scattered-to-broken and the rain, each day, never got anywhere near our area. Now, instead of an easterly flow with showers as (once again)forecast, here we are stuck with a warm, humid southerly wind and oppressive, August-like, 70-degree dew points.

Posted by: MMCarhelp | September 23, 2009 1:33 PM | Report abuse

@MMCarhelp

Not sure if you are talking about CWG forecasts specifically, or local media/NWS forecasts in general, but taking a quick glance at our forecasts here over the past few days, in most cases we've been very purposely downplaying the chances of rain with predictions of "a few showers" and percentages of 40% or lower, except for a Monday-for-Tuesdsay forecast of a 50% chance of showers (when indeed there were showers that passed through mainly the northern and western suburbs). You can review all of our forecasts here.

Posted by: CapitalWeatherGang | September 23, 2009 2:21 PM | Report abuse

No, don't get the wrong idea. I wasn't getting on your forecasts here as much as some of the others....Accuweather, NWS, Weather Channel, etc...

I don't believe in picking on people for an occasional error in forecasting. Forecasting can sometimes be difficult (especially in this area, because of many variables with the ocean and mountains) and I've made errors myself. But several sources kept trying to move a stalled low-pressure system and front northward and eastward that was, obviously, just not going to happen. They didn't know when to quit. Then, when the Canadian High moved off the coast, it obviously went farther south than forecast and set up more of a hot, humid southerly flow than a cooler SE to NE one. So that's why we have July/August dew points today at the end of September.


I haven't forgotten the 94 degrees we had, though in October of 2007(I'm sure you guys remember that, too). That was a classic case of a late-season Bermuda High and upper-level ridge setting up (they used to call that "Indian Summer"), but that was one of the most classic examples I ever saw.

Posted by: MMCarhelp | September 23, 2009 6:36 PM | Report abuse

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