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Posted at 5:00 AM ET, 08/16/2010

Forecast: Sticky, stormy, unsettled week

By Jason Samenow

* Outside now? Radar, clouds, temps & more: Weather Wall *

updated at 9:30 a.m.

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

 

A troubling trifecta: heat, humidity, and thunderstorms.
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today: Partly sunny and humid. T'storms likely. 87-93. | Tonight: Evening storms, muggy. 72-76. | Tomorrow: Warm, chance of t'storms. 87-91. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Thick cloud cover has been our friend for the last several days, holding afternoon temps below average. To start this week, we'll continue to have our share of clouds, but we should have enough sun and tropical air flow to push temperatures back towards 90. While it heats back up, a cold front approaches the region and then stalls - serving as focusing mechanism for abundant tropical moisture surging northward. This means we may have to contend with shower and thunderstorm chances almost daily.

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): Tropical air is entrenched over the region today so be ready for high humidity levels. As we've seen a break in the cloud cover this morning, temps should have little trouble rising to near 90 or even a bit higher. With the sunshine destabilizing the atmosphere and a front approaching, the risk of showers and thunderstorms is high -- particularly this afternoon and evening (60-70%) but some scattered morning activity is also possible. While the most likely impact with these storms is heavy rain, a few storms this afternoon could be strong or severe -- with the possibility of damaging winds. Confidence: Medium

Thundercast:
Probability: 60-70%
Coverage: Scattered-widespread
Most likely timing: 3-9 p.m.

Tonight: Showers and thunderstorms remain possible through the pre-dawn hours, but a lot of the activity should shift east of I-95 after 10 or 11 p.m. Outside of the storms, it will be mostly cloudy and muggy, with lows in the low-to-mid 70s. Confidence: High

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

Tomorrow (Tuesday): The front causing today's storms stalls out somewhere in our vicinity tomorrow. Exactly where it's positioned is important for the forecast. If it can penetrate far enough south, that reduces the heat, humidity and storm chances. Unfortunately, it's probably going to remain sufficiently close for more showers and t'storms (40-50% chance) especially in the southern suburbs. Temps are near where they are today with highs around 90 (maybe holding in the 80s in the northern suburbs). Confidence: Low-Medium

Tomorrow Night: A few showers and storms may linger, especially south. Otherwise, it's partly cloudy and mild, with lows 66-73 (suburbs-city). Confidence: Medium

A LOOK AHEAD

A disturbance arrives from the west Wednesday traveling along the stalled front extending to our south and west. This disturbance means showers and storms are likely (60% chance), some of which may be heavy rain producers. Considerable cloud cover probably holds high temps in the low 80s. The rain slowly diminishes Wednesday night, with lows in the upper 60s to low 70s. Confidence: Medium

The stalled front remains close to the region Thursday, setting up the chance (30-40%) for more showers and storms, most likely in the afternoon and evening. Highs should be in the mid-80s with overnight lows near 70. Confidence: Low-Medium

On Friday, we may catch a break from storm chances as high pressure briefly pushes the stalled front far enough south to briefly dry us out. We should then have sufficient sunshine to boost highs through the 80s to around 90. Clouds may increase overnight as the next front approaches with lows around 70. Confidence: Low-Medium

The threat of showers and thunderstorms (30-40% chance) returns Saturday as the next front moves towards the region. This doesn't appear to be an all-day washout (at least at the moment) and partial sunshine likely helps temps reach the mid-80s or so. These storms may linger into the evening but end later at night, with lows near 70. Confidence: Low-Medium

We've heard this before, but if the front pushes far enough south, Sunday may end up being a decent day as high pressure tries to build in. Right now, I'll optimistically call for partly sunny skies and highs in the mid-80s, but this is a forecast you'll want to check again in the coming days. Confidence: Low

By Jason Samenow  | August 16, 2010; 5:00 AM ET
Categories:  Forecasts  
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Comments

What does "50% chance of rain" mean? Does it mean that it will rain for half the day? That it might rain for one minute sometime during the day? It doesn't say how long the rain will last if it does rain.

Posted by: foofoofoo | August 16, 2010 7:20 AM | Report abuse

"If the sun breaks out (a decent chance in the morning), ..."

Looks like a quite decent 100% chance now here in Rosslyn. Not at all like yesterday: sunny and hot when I left my house in Warren County and cloudy and cool in Herndon.

Posted by: eric654 | August 16, 2010 7:23 AM | Report abuse

@foofoofoo

See this link from our frequent question section for an explanation on rainfall percentages.

Posted by: Jason-CapitalWeatherGang | August 16, 2010 7:40 AM | Report abuse

And you think our weather has been extreme. Look at this video from Copenhagen, Denmark from August 14th:
http://www.youtube.com/watch?v=bVNMuFTfpUE

Posted by: stinkerflat1 | August 16, 2010 8:45 AM | Report abuse

"What does "50% chance of rain" mean? Does it mean that it will rain for half the day? That it might rain for one minute sometime during the day? It doesn't say how long the rain will last if it does rain."


It means exactly what it says. There is a 50% chance that it will rain at your particular location.

Posted by: MKadyman | August 16, 2010 9:04 AM | Report abuse

50% chance of rain also means 60% chance of power outages in Montgomery county. The 50% chance also doesn't account for the DC split (subtract 5%) or the NW Spotsylvania dry bubble (subtract 10% although lately they have been back to normal).

Posted by: eric654 | August 16, 2010 9:23 AM | Report abuse

The comments to this entry are closed.

 
 
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