Updates: Flash flood warning for southern Montgomery County

“Flash flooding is ongoing or expected to begin shortly,” the National Weather Service warned. Small creeks and poor-drainage areas are most vulnerable to flooding. Do not attempt to drive across a flooded road where the depth of the water may be deceptive.

12:15 p.m. — Showers have increased and some could be heavy this afternoon

Today’s forecast is a bit of a moving target as showers have increased across the region, cycling in and out from southeast to northwest. There are breaks between the showers, but also some embedded heavier downpours. Radar shows more showers developing southeast of the region which could be heavy in spots as they streak northwest through the afternoon.

The truth about the weather today may fall in the middle of our earlier forecasts; not as wet as our initial forecast issued at 5 a.m., but wetter than the 10 a.m. update signaled.

10:00 a.m. — Not as rainy today as previously anticipated

Radar and short-term models do not indicate as much rain as we were previously expecting today. Since this morning, the heaviest rain has focused east and southeast of the Beltway, and it has now exited the region.

The atmosphere is still very humid and pop-up showers could still occur any time but it will be dry more often than not.

A few showers later today could be heavy, especially this afternoon and evening. But we no longer expect widespread rainfall of 1 to 3 inches and some areas could end up with very little. Below is the updated rainfall forecast from the National Weather Service for the period 8 a.m. this morning through 8 a.m. Friday. We think this forecast is overdone but, given the nature of summertime downpours, it’s not out of the question a few locations see amounts this high or even a bit higher.

The most widespread heavy rainfall likely occurred last night in which a number of areas picked up 1 to 4 inches. Heavy amounts focused in Fairfax County, Southern Maryland, and locations out toward the Blue Ridge. The National Weather Service supplied a list of totals. At the airports, Reagan National picked up 0.56 inches, Dulles 0.76 inches, and BWI Marshall just 0.18 inches (through 9 a.m.).

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

3/10: With a surge of rain and humidity, you may choose to vent without timidity.

• Today: Showers with locally heavy downpours, humid. Highs: 80-84.
• Tonight: Showers gradually taper off, calm and humid. Lows: 67-73.
• Tomorrow: Isolated shower early? Then increasing sunshine, lower humidity. Highs: 79-83.

Considering the raging fires and smoke in the West, it’s hard to complain too much about high humidity and downpours here today. That said, some pockets of flooding could occur, especially near small streams and in poor drainage areas. Conditions improve considerably Friday into Saturday before humidity and shower chances increase again Sunday.

Today (Thursday): Showers are possible anytime, and localized heavy downpours are likely, especially in the afternoon and evening. But the sky may brighten at times as high temperatures reach for the low 80s. Humidity is oppressive with dew points in the mid-70s, while negligible breezes from the northeast offer little relief. Rainfall amounts are highly variable, but up to one to three inches could fall or even a little more, especially east of the city. Confidence: Medium-High

Tonight: Showers remain a likely feature well into the night, and a few could still be heavy. Humidity remains on the high side with calm winds. Lows are in the upper 60s to low 70s. Confidence: Medium-High

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Tomorrow (Friday): A fairly weak cool front does its best to clear most showers out in the morning and starts to lower humidity levels by the afternoon. Clouds break up enough for some occasional sunshine as well. Breezes are light from the north, and highs top out in the upper 70s to low 80s. Confidence: Medium-High

Tomorrow night: Lower humidity and calming winds allow temperatures to drop off nicely despite partly cloudy skies. Lows bottom out in the low to mid-60s. Confidence: Medium-High

High pressure does a fairly good job of holding off showers and humidity on Saturday. By afternoon, clouds build and a shower could pop up, but most activity should stay well to our south. Highs in the mid-70s are a treat. Clouds gather overnight, but showers remain sparse. Lows hold in the mid- to upper 60s. Confidence: Medium

Showers and humidity finally surge back into the area on Sunday ahead of an approaching cold front. Highs climb to the low 80s. Showers are likely to linger through the night with lows mainly in the upper 60s. Confidence: Medium

Monday hinges on the cool front pushing through strongly enough to clear the area out and bring another surge of drier air into the area. If the front is slower to move on, showers could still linger. Highs should be upper 70s to low 80s. Confidence: Low-Medium