D.C. area forecast: Warm and sticky heading into Labor Day. Stormy too?

2 p.m. update: Follow this post for the latest on storms this afternoon and evening from CWG severe weather expert Jeff Halverson: Scattered strong storms possible through this evening

Today’s Daily Digit

A somewhat subjective rating of the day’s weather, on a scale of 0 to 10.

7
The final day of meteorological summer will be, well, summer-like … with an afternoon/evening storm threat.

Express Forecast

Today: Partly sunny. 60% chance of p.m. storms. Highs: Near 90.

Tonight: Chance of evening showers/storms. Lows: 68-74.

Tomorrow: Partly sunny. 30-40% chance of p.m. storms. Highs: Near 90.

FORECAST IN DETAIL


Radar & lightning: Latest regional radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Yes, today is the last day of meteorological summer 2014. And, yes, the atmosphere will behave like it’s summer. August’s final offering is several degrees warmer than yesterday, with continued high humidity thanks to persistent flow from a Bermuda high-pressure system. Scattered showers and storms could interrupt your plans this afternoon and evening, while Labor Day looks similarly warm and humid with a lower risk of showers and storms. Then, just as most of us head back to work and school on Tuesday, the heat really cranks, making for one of the more uncomfortable days we’ve seen in a while.

Today (Sunday): We start out similar to yesterday, with a partly sunny sky and sticky feel to the air. It’s noticeably warmer than Saturday, though, as we get into the late morning and afternoon, with highs peaking near 90. Showers and storms should fire up west of the area in the early afternoon, and by mid-to-late afternoon (mainly after 3 p.m. or so) we have a 60% chance of showers and storms locally. Any storms that do develop could be slow-movers that produce heavy rain, and could affect parts of the area – in scattered fashion – into early evening. Winds are generally light from the southwest around 5-10 mph, but could turn gusty for a time if you are near or within a storm. Confidence: Medium-High

storm threat
Tonight: Shower and storm chances continue around 60% into the early evening. Coverage should shrink dramatically by mid-evening (by around 8-9 p.m.), though some activity could linger later, especially over eastern and southern parts of the area. Partly to mostly cloudy skies prevail overnight, as will a muggy feel to the air. Temperatures bottom out in the upper 60s across the outlying areas to the mid-70s downtown. Confidence: Medium

For related traffic news, check out Dr. Gridlock. Keep reading for the forecast through the weekend…

Tomorrow (Labor Day): If you’re headed to the pool one last time, enjoying a barbecue, or catching one of the area’s season-ending minor league baseball games, expect more of the same: partly sunny, warm and humid, with a risk of afternoon/evening showers and storms. However, shower and storm coverage should be less than Sunday, with a 30-40% chance of getting wet in any given location. Highs should be similar to today, heading up to near 90 again. Confidence: Medium

Tomorrow night: Any shower and storm activity should end by mid-to-late evening, followed by a pronounced clearing trend into the overnight hours as a new area of high pressure moves into the region. There won’t be much change in the air mass, though, as muggy conditions continue and lows only drop into the mid-60s across the far northern and western suburbs, to the low-to-mid-70s inside the Beltway. Confidence: Medium

A LOOK AHEAD

Tuesday will feel hotter as sunshine returns and the same general pattern remains intact. Highs should reach at least the low 90s in most spots, and mid-90s is not out of the question, with perhaps a bit less humidity. We’ll have to watch the potential for that sunshine to be “self-destructive” and destabilize the atmosphere (in conjunction with a weak disturbance tracking to our north). If so, showers and storms could develop during the late afternoon into evening, but for now chances are on the low side. Confidence: Medium

Temperatures cool several degrees on Wednesday behind the disturbance. More comfortable, less humid air also filters in as dew points should drop into the low-to-mid-60s. Far from “refreshing,” but at least with highs generally in the mid-upper 80s, it should feel more like a “normal” early September day. Confidence: Medium

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