Wednesday, July 18, 2007
Mugginess Returns, Storm Threat Elevated
Delightfully Dry Weekend Likely
Jason Samenow @ 8:15 AM
Literally overnight, an offensively humid airmass has taken over the tolerably dry (albeit hot) airmass we experienced yesterday. Our now "juiced" atmosphere is primed to trigger showers and storms before it's sent packing in time for the weekend.
Hot and very humid, PM storms possible. You'll notice the increase in humidity as soon as you walk outside courtesy of a warm front that moved through yesterday evening. In the morning hours, we'll have a mix of sun and clouds with temperatures rising through the 80s. During the afternoon, thunderstorms are possible at any time (starting as soon as the early-mid afternoon) and your location will have a 50% chance of getting in on the action through the evening hours. The storms will be capable of producing very heavy rain, gusty winds and dangerous lightning. I would not be surprised to see a Severe Thunderstorm Watch issued as the Storm Prediction Center indicates we have a slight risk of severe storms. An isolated tornado or two could form but probably east or north of our immediate area. High temperatures should be right around 90 degrees.
Overnight, it will be partly cloudy and sultry, with lows 70-75 (suburbs-city).
Mostly clear skies on the Capital Mall yesterday evening. By CapitalWeather.com photographer Ian Livingston.
Steamy, and stormy? The moist tropical airmass will stay in command for one more day. It will be hot and humid with highs 90-95. Heat indices will be up near 100. Storm chances will be similar to today (50%), but most likely later in the afternoon and into the evening. Once again, any storms that form could produce very heavy rain and strong winds.
Overnight, showers and thunderstorms remain possible (30% chance), with lows 70-75.
Not as hot, decreasing rain chances. A cold front will move through the area from west to east beginning in the morning, and taking most of the day to clear to the east of here. As a result, clouds and lingering showers are possible, particularly east of the Metro area. High temperatures are likely to be in the mid to upper 80s with humidity levels remaining a bit sticky but a bit below the previous two days.
Overnight, humidity levels should slowly decline, skies should clear and temperatures should fall. Expect lows 62-67 (suburbs-city).
A breath of fresh air. Canadian high pressure will build in from the Midwest resulting in significantly cooler and drier air. High temperatures should be in the low to mid 80s with partly sunny skies and low humidity levels. A bit of instability and cold air aloft may allow for an isolated shower or two late in the afternoon both days but chances are pretty remote (20% or less).
Washingtonians dreading suffocation from the usual (and wrongly predicted) thick, moisture-laden air during their lunch breaks yesterday were pleasantly surprised when they walked outside and were greeted by desert-like dry air. The cold front, which was supposed to stall to our north had slipped just to our south allowing a pocket of uncharacteristically dry air to briefly envelop the area.Dewpoints bottomed out at 50 degrees (it was drier in DC than in Phoenix)! But during the late afternoon and evening, dewpoints surged back to the uncomfortable 60s as the cold front lifted back north as a warm front. Now, the moist air is socked in and dewpoints will be near 70 today.
Dewpoint data (shown to the right) is from Reagan National Airport yesterday.
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Today
Hot and very humid, PM storms possible. You'll notice the increase in humidity as soon as you walk outside courtesy of a warm front that moved through yesterday evening. In the morning hours, we'll have a mix of sun and clouds with temperatures rising through the 80s. During the afternoon, thunderstorms are possible at any time (starting as soon as the early-mid afternoon) and your location will have a 50% chance of getting in on the action through the evening hours. The storms will be capable of producing very heavy rain, gusty winds and dangerous lightning. I would not be surprised to see a Severe Thunderstorm Watch issued as the Storm Prediction Center indicates we have a slight risk of severe storms. An isolated tornado or two could form but probably east or north of our immediate area. High temperatures should be right around 90 degrees.Overnight, it will be partly cloudy and sultry, with lows 70-75 (suburbs-city).
Mostly clear skies on the Capital Mall yesterday evening. By CapitalWeather.com photographer Ian Livingston.
Tomorrow
Steamy, and stormy? The moist tropical airmass will stay in command for one more day. It will be hot and humid with highs 90-95. Heat indices will be up near 100. Storm chances will be similar to today (50%), but most likely later in the afternoon and into the evening. Once again, any storms that form could produce very heavy rain and strong winds.Overnight, showers and thunderstorms remain possible (30% chance), with lows 70-75.
Not as hot, decreasing rain chances. A cold front will move through the area from west to east beginning in the morning, and taking most of the day to clear to the east of here. As a result, clouds and lingering showers are possible, particularly east of the Metro area. High temperatures are likely to be in the mid to upper 80s with humidity levels remaining a bit sticky but a bit below the previous two days.Overnight, humidity levels should slowly decline, skies should clear and temperatures should fall. Expect lows 62-67 (suburbs-city).
The weekend
A breath of fresh air. Canadian high pressure will build in from the Midwest resulting in significantly cooler and drier air. High temperatures should be in the low to mid 80s with partly sunny skies and low humidity levels. A bit of instability and cold air aloft may allow for an isolated shower or two late in the afternoon both days but chances are pretty remote (20% or less).Yesterday's Dewpoint Excursion
Washingtonians dreading suffocation from the usual (and wrongly predicted) thick, moisture-laden air during their lunch breaks yesterday were pleasantly surprised when they walked outside and were greeted by desert-like dry air. The cold front, which was supposed to stall to our north had slipped just to our south allowing a pocket of uncharacteristically dry air to briefly envelop the area.Dewpoints bottomed out at 50 degrees (it was drier in DC than in Phoenix)! But during the late afternoon and evening, dewpoints surged back to the uncomfortable 60s as the cold front lifted back north as a warm front. Now, the moist air is socked in and dewpoints will be near 70 today.Dewpoint data (shown to the right) is from Reagan National Airport yesterday.
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