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Posted at 05:00 AM ET, 07/28/2011

Forecast: Heat and humidity on the rise; triple digit, record heat likely Friday

Code orange air quality: Unhealthy for sensitive groups
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The humidity is not unbearable yet and another day in the 90s...ho hum
 
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EXPRESS FORECAST

Today: Sunny, increasingly humid. 91-96. | Tonight: Fair and muggy. 70-78. | Tomorrow: Excessive heat and humidity. 97-102. | Get Express Forecast by E-mail

FORECAST IN DETAIL

Here we go again! After a brief flirtation with drier air, we are back on track for another trio of sultry days. Searching hard for a silver lining, these days should not be as hot as the same period a week ago. But we still must contend with likely record-setting, triple digit heat Friday and little relief at night. This is what I call “permaheat”, when the soils are so warm that they re-radiate the day’s heat like crazy after dark. So expect more record warm nights, adding to the five we already have this month.

Today (Thursday): The crystal blues skies are a thing of the past as a tireless sun and a weak breeze out of the south are enough to put haze back in the area. In fact, a code orange air quality alert has been issued, so don’t overdo it out there. Highs today range from the low-to mid 90s. Factoring in the humidity, peak heat indices near 100. Confidence: High

Tonight: Cooling is a slow process this evening with 80s prevalent. Light breezes from the south continue to pump in more humiditiy. Stars twinkle through the haze. There could be a few strokes of lightning on the far northern horizon late night but rain chances for the area are a mere 10%. Lows range from the lower 70s suburbs to upper 70s downtown. Confidence: High

Keep reading for the forecast through the weekend...

Tomorrow (Friday): It is quite likely that heat advisories and/or excessive heat warnings will be needed for this day. Dewpoints climbing into the 70s are going to have the air conditioning humming non-stop. Light breezes from the west should all but ensure that record heat is achieved in much of the area. You know the drill; drink lots of fluids and hold down the outdoor exertion. Highs range from the upper 90s to lower 100s. Reagan National Airport’s record of 99 (from 1993) is well within reach. Heat indices should be in the 105 to 110 range. Confidence: High

Tomorrow night: The weakest of cool fronts passes through and about the only way to tell is a light wind out of the north and a 10% chance of a thundershower. Otherwise, humidity hangs tough as does heat. Evening readings hang in the upper 80s to lower 90s. Overnight lows do no better than mid -70s burbs to near 80 in the city. Confidence: High

A LOOK AHEAD

Saturday is better only in comparison to Friday. Humidity remains uncomfortable. Partly sunny skies are sufficient to allow temperatures to climb into the mid-to-upper 90s in most locations. There is another slight chance for a thundershower in the late afternoon, 20%, but most of the activity is likely to slip just south of us. The evening remains on the muggy side. Lows should be in the mid-to-upper 70s. Confidence: Medium-High

Sunday is ever so slightly better than Saturday. The air is slightly less humid and temperatures should be a degree or two slower to climb. However, the sun is blazing so don’t get too carried away with outdoor activities. Highs should hold mainly in the mid-90s. Evening temperatures slowly fall through the 80s. Lows range from near 70 outside the beltway to mid-70s downtown. Confidence: Medium-High

Monday is still warmer than normal but humidity is almost manageable. Skies are mostly sunny but pop up clouds give some occasional afternoon shade. Highs peak in the lower-to-mid 90s. Confidence: Medium-High

By  |  05:00 AM ET, 07/28/2011

Categories:  Forecasts

 
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