... High pressure will build overhead through tonight before moving offshore Friday through Friday night. A cold front will pass through the area Saturday, then high pressure will return for Sunday into Monday. Low pressure and its associated cold front may impact the area during the middle portion of next week.
NEAR TERM /THROUGH TONIGHT/...
10 AM Update: Elevated winds will continue over the next several hours as the pressure gradient stays tight across the Mid-Atlantic region. High pressure will gradually move closer overhead by the end of the day and allow winds to diminish. Daytime highs will be 10 to 15 degrees colder than Wednesday afternoon with a colder airmass in place behind the cold front. Overnight lows will dip down into the 20s for most areas with a few clouds lingering for the first half of the night.
Previous Discussion Follows: High pressure will continue to build toward the area behind a cold front through this afternoon. Gusty northwest winds are expected through midday ahead of the building high, before gradually diminishing later this afternoon. The northwest winds along with chilly conditions will make it feel blustery and cold today, despite sunshine. Highs will range from the 20s and lower 30s in the mountains to the 40s for most other locations, with near 50 in central Virginia.
High pressure will settle overhead tonight, causing light winds. There will be some cirrus clouds, but the cloud deck should be thin so radiational cooling is expected tonight. Min temps will range from the teens and lower 20s in the colder valleys and rural areas, to the mid and upper 20s for most other locations with near 30 in downtown Washington and Baltimore.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... High pressure will move offshore Friday and a southerly flow will develop. The southerly flow with sunshine will allow for a more seasonable afternoon with highs in the upper 40s to mid 50s for most areas (lower to middle 40s in the mountains).
A cold front along with its associated upper-level disturbance will move through the Great Lakes into the Ohio Valley Friday night. A southerly flow will strengthen ahead of this system, allowing for Friday night to be milder with lows in the upper 30s to mid 40s for most areas. However, moisture advection along with divergence aloft in the upper-level jet means that clouds will increase and chances for precipitation will increase overnight. The best chance for rain will be west of Interstate 95 to the Allegheny Highlands toward morning.
Rain will overspread the rest of the area for a period Saturday as the cold front moves east. There will likely be a break in the precipitation later Saturday morning into Saturday afternoon, but a few showers are possible until the cold front passes through later Saturday afternoon into Saturday evening from northwest to southeast. Breezy conditions are expected ahead of the cold front, with the strongest winds most likely in the mountains. Frequent gusts around 25 to 35 mph are most likely in the valleys with 40 to 45 mph most likely in the mountains. A few gusts around 50 mph are possible along the highest ridge tops and perhaps just east of the Allegheny Front (downsloping flow), but confidence is low at this time.
High pressure will build overhead behind the cold front Saturday night bringing a return of dry and chilly conditions.
LONG TERM /SUNDAY THROUGH WEDNESDAY/... Strong ridging will be building over Greenland and Alaska heading into next week. In between, troughing dipping out of Canada will be battling with ridging over the Gulf of Mexico.
The result locally will be a period of unsettled weather as a front system and areas of low pressure waver about the area. Most of the area should see any precipitation fall as rain, but there may be just enough cold air at times near the Mason- Dixon line and near/west of the Blue Ridge Mountains for a bit of a wintry mix (mainly Monday-Tuesday).
Temperatures are expected to trend warmer the first couple days of next week before trending cooler Wednesday into Thursday.