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Posted at 05:00 AM ET, 07/23/2011

Forecast: Heat passing peak, but still dangerous; D.C. breaks record high for the day

Excessive heat warning today | Heat advisory tomorrow
Code red air quality today: unhealthy for general population
Heat wave & hot weather guide | Submit your hot weather photos

5:30 p.m.: D.C. hit high of 102 today, a new record for the date. More details and other area record info here.

4:15 p.m.: National Airport has reached at least 101 degrees today, which ties the record for the date from 1991. Dulles has also tied its record for the date, reaching at least 99 so far. The heat continues tomorrow though not quite as bad (heat index around 105 compared to today’s ~110, thus a Heat Advisory in effect tomorrow noon to 8 p.m. rather than the more serious Excessive Heat Warning that remains in effect today until 8 p.m.

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EXPRESS FORECAST

Today: Partly sunny, hot. Afternoon storm? Near 100 to low 100s. | Tonight: Partly cloudy. Mid-70s to near 80. | Tomorrow: Partly sunny. Afternoon storm? Mid-90s. | Get Express Forecast by E-mail

FORECAST IN DETAIL

All the precautions advised for yesterday should be taken again today. Air quality remains unhealthy for all groups, and the heat can still be a danger. We may not see all-time record highs broken up and down the East Coast like we did yesterday, but the heat stays on blast furnace. Continue to limit outdoor time, especially during peak heating from late morning into late afternoon. If you must spend time outdoors, please carry a jug or two of water with you at all times!

Today (Saturday): Air quality remains horrendous as we continue to simmer under temperatures rising to near or above 100 during the afternoon. The record at National of 101 may be in jeopardy . Heat indices may fall short of the astonishing 120+ we saw near D.C. yesterday, but they should still easily get into the dangerous 110-115+ range. A potential saving grace is the threat of an afternoon shower or storm. Like yesterday, they may be hard to come by outside the hills -- about a 20-30% chance. Any storms that fire in this environment can be strong to severe, with heavy rain and isolated damaging wind the main threats. Confidence: Medium-High

Tonight: We start with the remnant chance of a shower or storm, and then we just stay rather muggy and still quite warm. This may be the first sub-80 overnight in D.C. in a while, but it’ll be close as lows reach the mid-70s to around 80. Confidence: Medium-High

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

Tomorrow (Sunday): Heat continues to relent a bit heading into Sunday. How much is still sort of up in the air. The odds of showers and storms, plus the clouds they bring rises a bit as we get closer to the edge of the large upper high over the country. If we see numerous clouds, temperatures probably rise toward the mid-90s, but with extra sun another day with highs into the upper 90s is possible. As with today, any storms that fire in this environment can be strong to severe. Hard to give them more than 30% chance right now. Confidence: Medium

Tomorrow night: The risk of showers and storms from the late day persists into the evening before waning overnight. Lows should range from the low 70s to the upper 70s. Confidence: Medium

A LOOK AHEAD

Come Monday there’s still some uncertainty here as well as to ultimate highs, but it’s likely the step-down back toward normal D.C. heat continues. Look for a range from near 90 to the mid-90s. There’s that afternoon shower and storm risk again as well, and I think it could end up higher than prior days coverage wise. Confidence: Medium

By Tuesday, we may get an additional respite from high heat, but there’s already signs of a new surge from the west. From here it seems like we at least get the shot at a fairly decent day, especially compared to recently. Highs rise into the upper 80s and near 90, hopefully with lower humidity. Confidence: Medium

Unfortunately, it seems like a pretty good bet that heat heads back up as we get from mid-to-late week. How high it goes is not yet fully known, but more 95-100 readings appear possible. Confidence: Medium

By  |  05:00 AM ET, 07/23/2011

Categories:  Forecasts

 
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