wpostServer: http://css.washingtonpost.com/wpost

The Post Most: Local

Posted at 05:00 AM ET, 08/26/2011

Forecast: A warm and summery calm before Irene; tropical storm warning issued

Hurricane Tracking Center with Tweets from NHC
Live Chat with Hurricane Expert Greg Postel: 11 a.m.
Irene: Are You Prepared?
Live Video @ 10 a.m.: DHS Secretary, FEMA Administrator, NHC Director, Red Cross President
Live webcams of East Coast beaches

6:00 a.m. update: The tropical storm watch for D.C. and Baltimore areas has been upgraded to a Tropical Storm WARNING, this includes the tidal Potomac and the Maryland portion of the Chesapeake Bay. It does not include the western suburbs of Loudoun, Fauquier, and Frederick counties. A Hurricane Warning is in effect for the Virginia, Maryland, and Delaware beaches all the way up through the New Jersey shore and the mouth of the Chesapeake Bay. A Flash Flood Watch has also been issued for the metro region (except western counties) Saturday afternoon through Sunday morning.

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

 
Reduced chances for rain and a bit more sunshine. Irene's threat compromises my usual Friday giddiness.
 
Get the 'Digit' on Twitter
EXPRESS FORECAST

Today: Partly sunny. Afternoon storm? Mid-80s to near 90. | Tonight: Increasing clouds, showers possible after midnight. Low-to-mid 70s. | Tomorrow: Increasing rain and wind threats. Near 80 to mid-80s. | Sunday: Morning rain possible, clearing and breezy. Mid-80s. | Get Express Forecast by E-mail

FORECAST IN DETAIL

While we begin to get a whiff of Irene’s effects in the next day or so, we probably eke out a standard summertime one first. Folks along low-lying areas can hopefully use this to get their plan of action in place, and preparations done. D.C.’s Department of Public Works is even distributing sandbags today and tomorrow, as I’m sure other municipalities are too. Just to reiterate, Irene is a large storm and -- while the track may shift -- effects will still be felt over a wide area. It is best for folks, especially east of I-95 and in low lying spots around the entire region, to pay attention and finalize preparations.

Today (Friday): We may have a few breaks in the clouds, but don’t expect a completely sunny or comfortable day. The weak front that pushed toward us yesterday fizzles over the area potentially bringing a morning sprinkle. Mid-morning to mid-afternoon are the best chances for sunshine, before a slight (20-30%) chance of thunderstorms arrives late day. Muggy, summery highs in the mid-80s to around 90 south of town (depending on amount of cloudcover) really could make us sweat by late afternoon. Ahead of tropical systems, we often have an area of subsidence (sinking air) that warms regions on its outer edges. Note that today is a good, relatively calm day (without strong breeze) to prepare. Confidence: Medium-High

Tonight: The first high clouds from Irene may start to stream overhead. You may see some stars, perhaps some muted moonlight with a few rings around it as the night goes on, but overall still an evening that you can enjoy (don’t be too anxious!). Irene slowly begins to pump in a stream of higher humidity, raising the dewpoint substantially, and a light breeze from the east picks up with the night. Just a few, brief showers are possible (20-30% chance) after midnight -- only indirectly associated with Irene. Lows just before sunrise should bottom around balmy low-to-mid 70s. Confidence: Medium

Keep reading for the forecast through the beginning of next week...

Tomorrow (Saturday): This is a tricky weekend forecast that depends upon the exact track of Irene. It appears the center of the storm stays east of the bay or even just offshore; however, we still are likely to feel effects around the region. A low risk of morning showers increases as the day wears on, and by late day it could potentially become a steadier bout of storminess (especially east and south). Breezes pick up to 15-25 mph+ by afternoon with higher gusts as highs top out near 80 to the mid-80s.

If the track shifts west more toward D.C., we would have longer bouts of heavier rain and stronger wind over a larger area of our region. And a shift to the east could produce less wind/less rain. We’ll have more on the details later today. Confidence: Medium

Tomorrow night: Local effects of the storm may reach their peak as early as the evening or later at night depending on storm speed. Rain is likely over most of the area during this time, with near 100% certainty over eastern sections and perhaps 60-70% way out west. Winds steadily increase from 15-25 mph in the early evening to 20-30 mph prior to midnight. Gusts to 45 or 50 mph are possible when stronger rain bands move through. Lows are even more tropical than recently, in the low-to-mid 70s. Confidence: Low-Medium

Sunday: Winds diminish during the morning while turning from north to northwest. Rain either briefly lingers or is already totally gone during the morning it seems. Remember the subsidence that made us warm ahead of Irene? Highs may again bump up to the mid-80s or higher because of this, and also it helps provide us some nice blue skies. Confidence: Low-Medium

A LOOK AHEAD

Sunday night’s winds, if still substantial, should quickly wane as the storm heads way off to the northeast. With lows in the mid-to-upper 60s and a drying northwest breeze, you’ll say... ahhhhh. Confidence: Low-Medium

Monday and Tuesday features the calm after the storm with clear skies, light winds, lower humidity and highs only in the low-to-mid 80s. Here’s to hoping we have minimal clean up duty! These two days could be real beauties. Just remember to put on sunscreen for me please! It could be very high UV readings again, with blue skies and nothing to filter the sunlight. Confidence: Low-Medium

By  |  05:00 AM ET, 08/26/2011

Categories:  Forecasts

 
Read what others are saying
     

    © 2011 The Washington Post Company