5:35 p.m. — Severe thunderstorms in southwest suburbs

We’re watching a thunderstorm in Prince William County which, around 4:45 p.m., was suspected to have a tornado associated with it. The tornado warning has since been changed to a severe thunderstorm warning, but there’s some indication that the storm may still be able to produce a tornado, given the right circumstances. As of 5:30 p.m., strong wind gusts were the main threat as the storm was moving east-southeast through Prince William County, including Manassas. It will probably reach Interstate 95 around 6:15 p.m.

Forecast through the weekend

The clouds hung around a bit longer than anticipated today, limiting the daytime heating needed for thunderstorm development. However, breaks in the cloud cover have finally made it into the D.C. area, and we should see enough late sunshine to create a more favorable environment for thunderstorm activity. Coverage should be scattered at best, but some of the storms that do pop up may become severe for a time, so it’s definitely one of those afternoons to keep an eye on the radar.

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Through Tonight: Scattered storms will continue to develop to the west and southwest of the District through the late afternoon and early evening. The best chance for thunderstorm development in our immediate area will be from 4 to 8 p.m., with the most favorable thunderstorm environment being south of Route 50 and east of I-95. Some storms may reach the severe threshold, with gusty winds and small hail being the main hazards. Storm activity will wane and push east after sunset. Mostly cloudy and mild overnight, with lows in the upper 60s to low 70s and light winds from the west.

View the current weather at The Washington Post.

Andrew Jackson greets tourists on a cloudy morning in Lafayette Square. Tom Mockler via Flickr.

Tomorrow (Sunday): Mostly sunny skies will develop in the morning and persist for much of the day. Sunday will certainly feel much warmer and more humid than today. Under a west wind at 10 mph, afternoon highs will be right around, if not a few degrees above, 90, with dew points in the low 70s. There is a slight chance of some isolated afternoon thunderstorms developing, especially over elevated areas west of the city. That said, I expect that most of us will stay dry. Partly cloudy and more comfortable tomorrow night, with cooler conditions and decreasing humidity. Lows will be in the mid-60s as winds switch to the northwest at 5 mph.

See Ian Livingston’s forecast through next week. And if you haven’t already, join us on Facebook and follow us on Twitter and Instagram. For related traffic news, check out Gridlock.

July 4 Heat: Expect a hot edition of Independence Day this year. Recent runs of long-range-model guidance are providing growing evidence of an extended heat wave developing over the eastern half of the country during the first week of July.

The Climate Prediction Center’s 8-14 day temperature forecast shows a very high likelihood of above-average temperatures to start July.

Next week, the last week of June, excessive heat will start to build over the Midwest, while we stay relatively tranquil and average around our region. But about seven days from now, the semi-permanent feature known as the Bermuda High will shift its center to the west, bringing it closer to the East Coast. That will lead to the development of a huge and quite strong area of high pressure known informally as the “heat dome.” And once the dome is in place, it does not break down quickly.

500 millibars (about 18,000 feet above surface height anomalies show the heat dome in full swing right before July 4.)

The District hit 100 degrees on Independence Day in 1919, a record for the date. Can we hit that number again in 2018? All right, that was an unfair tease. There is no way of knowing the exact temperature this far in advance. However, I can safely say that if you are spending your July 4 somewhere east of the Mississippi, you are going to be hot.

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