Muggy; Thunderstorms Possible

A ridge of high pressure is weakening over the Mid Atlantic area, but the setting is still at "steamy" on the muggo-meter in the Washington metro area. Dulles had reached 90° by 2pm, but National was still no higher than 89° at 4pm. Dewpoints around the region were mostly in the upper 60s, with some at 70° or above.

In a pattern similar to yesterday's, showers and thunderstorms, some of them heavy, have broken out in the mountains to the west. In spite of very weak steering currents aloft, these do have some eastward motion. At post time, they had begun crossing I-81 in Virginia. The heaviest storms were mainly west of Winchester.

Some of these storms may make it as far as at least the western suburbs by this evening. Isolated storms could also break out at any time. At 4:16, the National Weather Service issued a Special Marine Warning for a small, but strong, thunderstorm moving slowly eastward over Baltimore harbor.

Tonight and Tomorrow

Tonight will be warm and humid with a 40% chance of thunderstorms through this evening, especially to the west of the District. Some storms may be severe, and locally heavy downpours are possible. Lows will be from the upper 60s to low 70s. Tomorrow will be mostly cloudy with showers or thunderstorms likely and highs in the low 80s.