... A Bermuda high will remain in place offshore over the next few days, keeping warm and humid air in place across the region. A cold front will approach the area by mid-week, before progressing to our south later in the week.
NEAR TERM /THROUGH TONIGHT/... Shower and thunderstorm activity has died down as the sun has set, with the few lingering showers fizzling out. Could see some patchy fog may be possible again to the west of the Blue Ridge, especially in sheltered mountain valleys where it rains today. It will be rather muggy overnight, with lows ranging from the upper 60s in the mountains to the upper 70s for DC, Baltimore, and along the bay.
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... A similar pattern will persist into tomorrow, with a warm, humid airmass in place and weak flow aloft. Showers and thunderstorms will again form within a lee trough. The positioning of the trough may be slightly further east tomorrow, allowing greater chances for thunderstorms to make it a little further east. Environmentally speaking, soundings look fairly similar as well, although there may be a touch more dry air at mid-upper levels. This could make downdrafts a touch stronger, but damaging winds from downbursts aren't expected to be a major issue. Precipitable water values will remain elevated (at near 2 inches), making heavy rainfall possible in association with any storms. Widespread hydro issue are not expected though. Highs tomorrow will be in the low-mid 90s, with dewpoints holding in the low-mid 70s.
A weak disturbance will pass to our north across Upstate NY and New England on Tuesday. This will drive a weak cold front southward into Pennsylvania. The warm/humid airmass will remain in place locally, which along with daytime heating/terrain circulations/bay and river breezes, should be enough to initiate some showers and thunderstorms once again during the afternoon and evening hours. Soundings show a bit more dry air in the mid- upper levels, and as a result, higher DCAPE values. As a result, there may be a greater chance for storms producing some localized downbursts of damaging winds relative to preceding days. Isolated instances of flash flooding may be possible as well, with precipitable water values remaining elevated at around two inches. Highs will once again be in the low-mid 90s, with dewpoints in the low-mid 70s.
LONG TERM /WEDNESDAY THROUGH SUNDAY/... Troughing will dig into the eastern U.S. for the second half of the week. A cold front will likely be able to find its way at least partially through the region during this time due to the added forcing from aloft and moderately strong high pressure pushing in at the surface behind it. Showers and thunderstorms are likely on Wednesday as the front makes its main push across the area.
Humidity will fall markedly later in the week in the wake of the front. Much drier weather is anticipated late Thursday through much of the upcoming weekend as a result. Temperatures will tumble to slightly below seasonable norms as well, with some guidance indicating the potential for lows in the upper 40s Saturday morning over the higher terrain.