Flood watch until late tonight | Extremely heavy rain swamps Prince George’s County | Two dozen homes evacuated in Prince George’s County *

Some short-range high resolution models indicate another round of storms could sweep through the region between around 4 and 8 p.m. this evening.  Heavy rain, thunder, lightning and some strong (but probably not damaging) wind gusts are possible.  The chance of storms, overall, is around 60 percent.

Here’s a look at simulations from two short-range models:

High resolution NAM

High resolution NAM radar simulation 4-8 p.m. Tuesday (WeatherBell.com)


HRRR model radar simulation 4-8 p.m. Tuesday (WeatherBell.com)

Sometimes these model simulations are overdone, so it’s not  a guarantee widespread storms break out.

“A big outflow boundary (pool of stable, rain-chilled air) has spread across southern Md, northern Va. and DC from this morning’s heavy rain cluster,” says Jeff Halverson, Capital Weather Gang’s severe weather expert. “This may shut down activity over the immediate metro region for a few hours, but concentrate it along the fringes of the boundary. For now, satellite and radar showing a line of activity beginning to congeal over the high terrain to our west. I expect this will grow and intensify as it moves east, as supported by the NAM and HRRR simulations.”

There is plenty of moisture and instability to support some heavy storms.

“With weak winds, a remnant boundary [front] and high low level moisture, I do see the possibility of localized heavy rainers,” says Capital Weather Gang severe weather expert Jeff Halverson.  

Unlike this morning’s storms which stalled over the same areas, there should be enough flow to move these storms along (though not particularly quickly).

Areas in northern Prince George’s County hit earlier by heavy rains will be especially vulnerable to flash flooding.

Although storms may produce some strong wind gusts, widespread damaging winds and/or large hail are not likely.  Wind shear is “low-end” Halverson says.