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Posted at 4:15 PM ET, 09/26/2010

Forecast: Bye-bye heat wave, hello rain clouds

By Jason Samenow

* National hits 90+ for record-tying 67th time | NatCast *
* Radar, clouds & more: Weather Wall | Hurricane Tracking Center *

originally posted at 5 a.m.; updated at 8:55 a.m. & 4:15 p.m.

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

 

Showers on a weekend are no fun. But we need some rain, and the air finally feels fall-like.
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today: Some showers. Low 70s. | Tonight: Chance of rain, especially late. 55-60. | Tomorrow: Showers & a chance of t'storms. Low-to-mid 70s. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Today brings a rather abrupt change in the weather regime. Warm winds from south and southwest are replaced by cool winds from the north and northeast and some showers. The end result is temperatures 20 to 30 degrees below levels reached yesterday and Friday. Intermittent rain continues possible through Tuesday. We'll have to carefully monitor conditions late Monday into Tuesday as instability and spin in the atmosphere may trigger some severe thunderstorms.


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 (Sunday): A solid area of showers, while mostly light, arrived surprisingly early this morning. We've seen an extended break since the initial surge of showers ended around midday. But with mostly cloudy skies and cooler air oozing in from the northeast, highs have only reached the low 70s. Confidence: Low-Medium

Tonight: Skies are overcast with rain chances on the increase as we get into the evening and overnight. Rain odds are about 30% prior to midnight, but 60% toward dawn. Temps fall off to around 60. Confidence: Medium

Keep reading for the forecast into early next week...

Tomorrow (Monday): Rain showers are likely in the morning (70% chance), as low pressure to the southwest lifts northward. Some locations -- especially along and east of I-95 -- may see a break in the action midday through mid-afternoon, before bands of showers and thunderstorms - moving southwest to northeast - develop late in the afternoon and into the evening. A few of these storms could be severe, especially to the east and southeast. High temps are likely in the low-to-mid 70s but could go somewhat higher if we get an interval of sunshine. Confidence: Medium

Tomorrow Night: Showers and thunderstorms - some with locally heavy rain - are likely (80% chance). A few strong to severe storms are again a possibility. Lows are in the 60s. Rainfall potential through Tuesday morning is around 1-2". Confidence: Medium

A LOOK AHEAD

The best chance of rain Tuesday is in the morning (60-70% chance), but scattered showers and thunderstorms could redevelop in the afternoon (30% chance) after a period of partial sunshine. Winds from the south ahead of a cold front could push temps briefly into the 80s. Becoming cooler Tuesday night, with lows in the mid-50s in the cooler suburbs to the low 60s downtown. Confidence: Low-Medium

Much more tranquil weather arrives Wednesday, with partly to mostly sunny skies and highs 75-80. Confidence: Medium-High

By Jason Samenow  | September 26, 2010; 4:15 PM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: NatCast: Cloudy and cool; showers?
Next: NatCast: Rain likely, but how heavy & when?

Comments

What is that big swath of green/yellow on the radar? I thought it wasn't supposed to rain until this evening???

Posted by: snowlover | September 26, 2010 7:36 AM | Report abuse

Yeah, we've got a few drops of rain here in Gaithersburg.

Posted by: hawknt | September 26, 2010 7:44 AM | Report abuse

now it's drizzling pretty good...

Posted by: hawknt | September 26, 2010 7:47 AM | Report abuse

steady drizzle here in Arcola near Dulles.
Tough tracking the cold front movement. First it was to be here yesterday and no 90s, then we were not going to see rain this morning.
BUT, rain is most welcome! Hopefully precursor to Mon & Tues.

Posted by: LoudounGeek | September 26, 2010 7:55 AM | Report abuse

Rain and ten degrees colder than DC at Gilberts Corner west of town.

Posted by: silencedogoodreturns | September 26, 2010 8:01 AM | Report abuse

Drizzle in Chevy Chase, but it looks like it may be stopping.

Posted by: summerlover | September 26, 2010 8:25 AM | Report abuse

60 degrees with gentle rain falling outside of Sperryville, VA, in a "holler" up against the Blue Ridge...already have had .1 inch...YAY!!!!!!!!...need lots more...

Posted by: NorthFork1 | September 26, 2010 8:32 AM | Report abuse

Showers in Laytonsville for the last 45+ minutes... just enough to effectively cancel my planned late morning mowing. Oh well, I guess I'll have to watch a couple of pre-game shows, instead. Very light drizzle now.

Posted by: dprats21 | September 26, 2010 8:37 AM | Report abuse

Looking at the current radar and track, it looks like we could see light rain all day! Bummer as I had outdoor plans today!!

Posted by: snowlover | September 26, 2010 8:45 AM | Report abuse

And I was just getting used to the heat.
:-(

Posted by: grobinette | September 26, 2010 8:58 AM | Report abuse

Forecast updated. Complete model fail as far as this morning's showers.

Posted by: CapitalWeatherGang | September 26, 2010 9:03 AM | Report abuse

Rain came in much earlier than we expected. Plume of moisture to the south surged north much more quickly than computer models were indicating and pretty much anyone was forecasting. It really seemed that high pressure to the north would keep us dry until tonight. I really thought I was going to get in a round of golf today. Now I'm not so sure.

Posted by: Jason-CapitalWeatherGang | September 26, 2010 9:11 AM | Report abuse

Centreville VA Light & moderate rain showers started here around 8:00AM.
So sorry about the many washed out Sunday plans......but we really need this rain. CWG, thanks for owning up on the rain arrival timing forecast FAIL :-)

Posted by: FIREDRAGON47 | September 26, 2010 9:56 AM | Report abuse

Hey CWG....What are the odds of the Nats/Phillies game getting washed out tomorrow night at Nats Park?

Posted by: TuscanRed | September 26, 2010 10:04 AM | Report abuse

Complete, utter, total, monumental, historic, tragic model fail more like it. Amazing how mad I am at weather forecasters this morning.

Posted by: Tony-Tony-Tony | September 26, 2010 10:04 AM | Report abuse

Adding another layer of nonsense to this, one of the current models, which was initialized at 12z (8am, at which point it was already raining here), still has the precip not making it to the southern DC area until 2pm.

Posted by: Brian-CapitalWeatherGang | September 26, 2010 10:09 AM | Report abuse

The sky is covered with gray in Michigan Park. I had to turn the lights on. Pavement wet. I can't remember seeing these things. What's going on?!?!


(guys I'm kidding ;-)

Posted by: kperl | September 26, 2010 10:12 AM | Report abuse

Why are the models so often monumentally wrong on the weekend?

Posted by: jojo2008 | September 26, 2010 10:17 AM | Report abuse

So is the Nats Cast going to be changed to RAIN for today? Or will it be dry?

Posted by: jaydreb1 | September 26, 2010 10:23 AM | Report abuse

There hasn't yet even enough rain to completely wet the sidewalk and we're ready to tar and feather the weather folks over a couple of sprinkles. So Washington.

Wonder when the last time afternoon temps were in the 60s around here? Because that may happen today.

Posted by: JerryFloyd1 | September 26, 2010 11:00 AM | Report abuse

Barely enough rain 2 make sidewalk wet. Sun is now out in Spotsy. Still skeptical about the amount of rain we will c., hope I'm wrong & it rains for 48 hrs.

Posted by: VaTechBob | September 26, 2010 11:46 AM | Report abuse

wow...what a difference a day makes: like about 25 degrees!

well, we tied that 90 degree record. looks like we'll need a rogue (heat) wave to break the record. sure would like to break that record, then get on with fall (love football sundays) and winter. actually, wouldn't mind a week or two of fall-like 60s-70s, then a 90-degree day in early october.

i saw that summery summary a few days ago, but i don't remember anything about the latest 90-degree day on record. anybody know when that is?

hail to the redskins!

Posted by: walter-in-fallschurch | September 26, 2010 11:48 AM | Report abuse

@Walter, CWG and may others have noted that the latest 90-degree day is (I think) Oct. 11. But CWG can verify.

Looking down the road, we might see a couple of low 80s later this week, but there seems to be a big shift taking place in the weather patterns, so 90-degree days are probably kaput. However, this has been said several times already and we've saw what happened.

After such a prolonged period of heat, how quickly will we acclimate to highs in the 50s, in perhaps a month?

Posted by: JerryFloyd1 | September 26, 2010 12:38 PM | Report abuse

ouch, grammatical near end of second paragraph in the above post. Should read:

However, this has been said several times already and we saw what happened.

Posted by: JerryFloyd1 | September 26, 2010 12:51 PM | Report abuse

Sun still out & temp has gone up 8 degrees since 11:30, now 70.
Still think there's another 90 day out over the next 2 weeks.

Posted by: VaTechBob | September 26, 2010 1:04 PM | Report abuse

october 11th, huh? ok...i'm predicting 91 degrees on october 12th.

Posted by: walter-in-fallschurch | September 26, 2010 1:16 PM | Report abuse

@jaydreb1

The NatCast was updated, and noted as so, shortly after this forecast was updated way back earlier this morning.

Posted by: Dan-CapitalWeatherGang | September 26, 2010 3:25 PM | Report abuse

@jojo2008

It does seem models have more trouble on the weekend, though scientifically there's virtually no reason that would be. I think it's more so that models aren't as good with late-night nocturnal into early-morning precipitation. And, people probably notice weekend forecast errors more so than weekdays because the weather tends to have a bigger impact on plans and activities on the weekend.

Posted by: Dan-CapitalWeatherGang | September 26, 2010 3:28 PM | Report abuse

@Tony-Tony-Tony

Not sure what your plans were this morning, but I'm betting a lot of folks with softball and other outdoor plans were just as frustrated. It's interesting that in the case of a lot of forecast busts, you'll look back at the models afterwards and see where you should've maybe seen something and could've made a better/different forecast. But in the case of this morning's rain, there was just nothing in any of the models to support even the mention of a shower chance until later in the day today. Frustrating for us (forecasters) and for all of you who depend on the forecasts. But for us at least, not quite as frustrating as blowing a forecast that could've/should've been better.

Posted by: Dan-CapitalWeatherGang | September 26, 2010 3:37 PM | Report abuse

@LoudounGeek

This morning's rain was a surprise, but the cold front behaved pretty much as expected, coming through during the early-to-mid part of yesterday. We had "near 90" in the forecast for yesterday as early as Friday morning, in anticipation of westerly downsloping winds behind the front and an expected delay in the cooler air mass filtering in. Though we may have been one of the few forecast outlets forecasting the potential for 90 yesterday.

Posted by: Dan-CapitalWeatherGang | September 26, 2010 3:50 PM | Report abuse

What are the models saying as of now about showers/t-storms around rush hour time (say, 4-8 pm timeframe) tomorrow? Any changes? Trying to plan some errands/activities for the family tomorrow, and part of the picture involves a new driver (age 17) who hasn't driven in rain a whole lot. She's been a great driver so far, but I don't want her in over her head with bad weather.

Weather input would be appreciated, so Mom and Dad can make the safety call.

Thanks!

Posted by: southbridgemom | September 26, 2010 4:17 PM | Report abuse

Come on guys, stop complaining about the drizzle/light rain this morning,and the fact that it came in early. I don't care if you did have outdoor actitivies planned......we are WAY behind on precip, and, right now, need every drop.

Posted by: MMCarhelp | September 26, 2010 4:49 PM | Report abuse

@Dan - thx for the update...

Posted by: LoudounGeek | September 26, 2010 5:09 PM | Report abuse

Looking at radar, it finally looks like a nice amount of rain is headed our way. I know the dance crowd will b in mourning, but too bad. My yard looks a desert & trees have been dropping leaves like crazy.
Nice wins 4 the Hokies & the Steelers, now if the Rams can beat the Skins & we get rain, my weekend will b complete.

Posted by: VaTechBob | September 26, 2010 5:53 PM | Report abuse

@southbridgemom

The best I can say is that there's a pretty good chance of showers and possibly thunderstorms at that time.

Posted by: Jason-CapitalWeatherGang | September 26, 2010 6:07 PM | Report abuse

Rain came in early [thanks to that dratted "much-needed rain" crowd, which now has found some method of witchcraft or voodoo or whatever to try "gaming" the model guidance!], but I was able to get in my trail hike--it actually cleared up a bit.

Now, let's find some way to keep the Redskins from LOSING all these "easy" games [e.g. Texans, Rams]. This is how the Redskins throw away what should be EASY opportunities to make the playoffs! I'm getting mighty tired of losers, losers, losers all the time. Even when our teams make the playoffs [e.g. the Caps], they seem to find a way to throw it all away in the first round. It seems that even having the best all-around record in the league [NHL] doesn't help our local teams.

Posted by: Bombo47jea | September 26, 2010 6:40 PM | Report abuse

Having a wonderful heavy rain shower in Centreville. A late wave of lettuce seeds put in about an hour ago, so that worked out nicely. Earlier plantings this month & in August have not done very well due to the excessive heat.

Posted by: FIREDRAGON47 | September 26, 2010 7:19 PM | Report abuse

Looking at the week ahead, Fall will finally be in the air.
Cooler temps with some rain, ahhhh...

Posted by: bodyiq | September 26, 2010 8:24 PM | Report abuse

"It does seem models have more trouble on the weekend, though scientifically there's virtually no reason that would be."

Well, there _is_ a "weekend effect" that has been measured in different regions due to differences in aerosol emissions during the week and the weekend, and aerosols interact with cloud, so therefore precipitation and diurnal temperature range... do weather-forecasting models take this into account?

http://climate.gsfc.nasa.gov/publications/fulltext/Bell-etal_JGR_2008.pdf and
http://www.pnas.org/content/100/20/11225.abstract
are but two examples of such effects.

Posted by: marcusmarcus | September 26, 2010 11:24 PM | Report abuse

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