CWG Live updates: Hot today with strong storms possible; more heat through midweek

Washington Post

21 hours ago

Welcome to cwg.live, updated around-the-clock by Capital Weather Gang meteorologists.
Happening now: A steamy Sunday with the heat index reaching 100 to 105 and a better chance of more numerous thunderstorms midafternoon into evening. Some could produce damaging winds and isolated flooding.
What's next? High heat continues through midweek, especially Tuesday and Wednesday when heat index values could reach 105 to 110, but storm chances are lower. Trending cooler and maybe more stormy again late week.
Today's daily digit — 3/10: A hard forecast to love with increased thunderstorm activity and uncomfortable heat. | 🤚 Your call?
The digit is a somewhat subjective rating of the day's weather, on a 0-to-10 scale.
Forecast in detail
Today (Sunday): Partly sunny, hot and very humid as afternoon highs hit the upper 80s (north) to mid-90s (south) and heat index values reach 100 to 105. Showers and thunderstorms have a shot to be more numerous today, with the best chance of scattered storms after 2 p.m. into the evening. Some storms could produce damaging winds and isolated flooding. Be prepared to move indoors quickly, if needed. Confidence: Medium-High
Tonight: A few strong to severe storms remain possible until around 8 or 9 p.m. Partly to mostly cloudy overnight with lows in the mid- to upper 70s. Confidence: Medium
Tomorrow (Monday): A frontal boundary sinks south on Monday, which clears us out and sunny skies return. The heat and humidity continue with highs in the low to mid-90s and heat indexes up to near or just above 100. Confidence: Medium
Tomorrow night: The overnight feels stagnant with lows in the mid- to upper 70s and partly cloudy skies. Confidence: Low-Medium
A look ahead
Sultry heat continues Tuesday and Wednesday with plenty of sun, highs in the mid-90s to near 100, and heat index values reaching 100 to 110. Shower and storm chances seem fairly low, maybe a better chance of one by Wednesday evening. Tuesday night and Wednesday night lows in the muggy 70s. Confidence: Low-Medium
A cool front moves in late week. The timing of the front is still a bit uncertain, but as of now it looks like somewhat cooler highs in the upper 80s to near 90 on Thursday, and perhaps only the low to mid-80s on Friday. But as temperatures decrease, shower and storm chances trend higher again. Confidence: Low-Medium
Today's daily digit — 3/10: A hard forecast to love with increased thunderstorm activity and uncomfortable heat. | 🤚 Your call?
The digit is a somewhat subjective rating of the day's weather, on a 0-to-10 scale.
Forecast in detail
Today (Sunday): Partly sunny, hot and very humid as afternoon highs hit the upper 80s (north) to mid-90s (south) and heat index values reach 100 to 105. Showers and thunderstorms have a shot to be more numerous today, with the best chance of scattered storms after 2 p.m. into the evening. Some storms could produce damaging winds and isolated flooding. Be prepared to move indoors quickly, if needed. Confidence: Medium-High
Tonight: A few strong to severe storms remain possible until around 8 or 9 p.m. Partly to mostly cloudy overnight with lows in the mid- to upper 70s. Confidence: Medium
Tomorrow (Monday): A frontal boundary sinks south on Monday, which clears us out and sunny skies return. The heat and humidity continue with highs in the low to mid-90s and heat indexes up to near or just above 100. Confidence: Medium
Tomorrow night: The overnight feels stagnant with lows in the mid- to upper 70s and partly cloudy skies. Confidence: Low-Medium
A look ahead
Sultry heat continues Tuesday and Wednesday with plenty of sun, highs in the mid-90s to near 100, and heat index values reaching 100 to 110. Shower and storm chances seem fairly low, maybe a better chance of one by Wednesday evening. Tuesday night and Wednesday night lows in the muggy 70s. Confidence: Low-Medium
A cool front moves in late week. The timing of the front is still a bit uncertain, but as of now it looks like somewhat cooler highs in the upper 80s to near 90 on Thursday, and perhaps only the low to mid-80s on Friday. But as temperatures decrease, shower and storm chances trend higher again. Confidence: Low-Medium
Because of the likelihood of heat indexes reaching at least 105 degrees, the National Weather Service has issued a heat advisory for D.C. and its southern suburbs on Sunday.
The advisory, which does not include Montgomery and Loudoun counties, as well as areas to the north, is in effect from noon to 8 p.m.
'Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,' the Weather Service says.
It's the third straight day with a heat advisory in D.C.'s far southern suburbs because of a punishing combination of heat and humidity that began Friday.
Sometimes in a meteorologically memorable Washington summer, such as this one, the heat of the day might fall a bit short in its severity, and then it is left to humidity to take over in producing discomfort, as it seemed to do on Saturday.
In the District, the official high temperature obviously was adequate to qualify as summer. The mercury reached 92 degrees. Perhaps not an automatic symbol of thermal suffering, but it was two degrees above the normal (or average) high for July 26, which is 90.
Yet it was not perhaps a fully fledged 90-degree day, in that many hours seemed to laze in the upper 80s. In addition, during two of the afternoon's hourly readings, the mercury hit 90 but it was just 90 and not higher.
After a time in many a summer, a day that deploys many hours of merely 90 degrees might lose its power to deter all thoughts of outdoor activity.
So if this summer is to hold its place as one of the region's seemingly less salubrious, the dew point must take a hand. It must hold up its end of the legendary heat-humidity partnership. The dew point reflects the power of humidity to make a day uncomfortable, even oppressive.