Evening Update: Anticipate showers and storms tonight, followed by reduced frequency on improving Wednesday

Mugginess continues with showers and storms tonight, most likely after we cool from our early evening 80s. Additional rounds of rain are possible Wednesday, even at night, when humidity slowly starts easing. While heavy storms with flooding downpours (threat evaluated further below) are slightly possible, at least any downpours will become spottier by later Wednesday.

Through tonight: Showers and storms look likely, especially by late evening into the pre-dawn hours. Some could be heavy. We’ll take a look at the flooding downpour threat below. Muggy upper 60s to low 70s will be as cool as we’ll get.

Tomorrow (Wednesday): It will still be a bit humid to start with temperatures eyeing the upper 70s and low 80s. Showers and even a storm will still be possible at any time, but the main thunderstorm chances may wait until midday and the afternoon hours as the cold front finally gets closer. Sunshine prospects will improve with time, as drier air tries to move in during the afternoon hours. We’ll be in a battleground area as this more comfortable air mass tries to move in — in fits and starts.

Overnight, humidity levels will improve with dew points heading down into the 50s — all riding in on noticeable northwesterly breezes. Low temperatures will try to mirror some of this increased comfort, dipping into the mid-50s to low 60s. A round of pop-up showers or a storm has a chance at developing in the evening hours, then again in the very early morning hours. The front will try to fully clear our area by dawn (finally eliminating these small rain chances).

Briefing on flooding downpour threat through tomorrow night

Our cold front is not able to fully make a clean break with our region until early Thursday but, slowly, overall rain chances are on the decline after tonight. A few downpours could cause some brief flooding concerns, but so far threats are limited. Here’s the weather-making front, slowly exiting to our east Wednesday night:

The front should take with it the main storm and downpour threat Thursday. With luck, everyone in the region will see some beneficial rains before it exits. The good news is at least a half-inch of rain is targeted in areas west of D.C. that could certainly use it.

Still, we have a small flooding aspect possible to these rains, especially tonight. Below, shaded in the green, is a 5 to 14 percent chance of seeing flooding from rainfall rates at least (even if briefly) one inch per hour. This graphic covers the time period until 8 a.m. Wednesday.

Even as the front tries to push through Wednesday, we’ll remain on the western (“marginal”) edge of the flooding downpour threat. At least rain chances are on the decline Wednesday, but pop-up storms with downpours do remain possible — even if spotty. The graphic below covers the time period until 8 a.m. Thursday.

Original Story at www.washingtonpost.com – 2023-09-12 22:16:13