... High pressure over the Upper Midwest builds eastward through Tuesday. Low pressure passing north of the Great Lakes will aim to lift a warm front through the area during the middle portion of the week. A cold front will approach the region thereafter before stalling in the region as we head into next weekend.
NEAR TERM /THROUGH TONIGHT/... High pressure is situated over the Upper Midwest this morning as a cold front extends off the Carolina coastline. Dry and pleasant conditions on tap today with a northerly breeze around 10 to 15 mph, gusting upwards of 25 mph at times through early afternoon. As the aforementioned high nudges closer today, winds will slacken this afternoon and remain on the lighter side through the overnight hours.
Dewpoints are quite comfortable this morning as surface observations highlight 40s area wide, indicating a much drier airmass compared to just a couple days ago when we had widespread dewpoints in the lower 70s. The drier airmass is also evident on water vapor imagery and the lack of clouds on the visible channel. Additionally, this mornings upper air sounding out of IAD measured a measly 0.37 inches of precipitable water, registering below the 10th percentile for the date.
Vibrant sunshine can be expected the remainder of the day as temperatures rise into the low to middle 70s under a cold air advection regime on the heels of the northerly breeze. Clear and seasonably chilly conditions tonight as the high centers over the Ohio Valley. Could see a few mid-high clouds creep in from the north overnight as we reside on the backside of the upper trough axis and the jet stream dips southward over the region. Otherwise, widespread temperatures in the 40s expected, hovering in the lower 50s in the city centers and near the larger bodies of water. Colder locations along the Alleghenies will dip into the upper 30s.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... High will continue to build southeastward toward and over the region through Monday night. Mostly clear skies, below normal temperatures, and dry conditions will be the resultant weather. Highs Monday will hold in the low to middle 70s, with overnight lows falling back into 40s to middle 50s.
Mid-upper level clouds will increase Monday night as we reside on the eastern periphery of an upper ridge and a weak shortwave seems poised to drop southeastward from the Great Lakes. Will hold on to a dry forecast Monday night, but wouldn't be surprised if low end chance POPs sneak in at some point, at least across northern Maryland and eastern West Virginia.
Rain chances return on Tuesday as a weak upper-level shortwave passes over the region. A surface warm front will also be lifting north, as surface high pressure shifts offshore. Given the warmer and more humid environment, can't rule out a thunderstorm Tuesday afternoon as well. Highs Tuesday reach the lower 80s.
LONG TERM /WEDNESDAY THROUGH SATURDAY/... At the start of the long term, a broad ridge will dominate the southeastern adn south central US, with cut-off lows over Atlantic Canada and southwest of southern California. A weak trough will be located over the Great Lakes. By Thursday, the ridge locally will weaken in the wake of the passage of the trough in the Great Lakes, which will help cause the closed low over Atlantic Canada to retrograde westward a bit. On Friday, another weak shortwave will cross the area as the closed low to the north starts retreating away from our area once again. By Saturday, yet another weak shortwave will cross the region, but by this point the whole ridge will start to buckle, expanding north across the Plains while being infringed by a new closed low over the Pacific Northwest, which will absorb the closed low southwest of California.
At the surface, a warm front will advance across the region early Wednesday, allowing very warm to borderline hot air to overspread the region for the first time this year. Highs may reach 90 in many areas. However, this may not last long, as most guidance then drops a cold front southward into the region by Thursday, though some models are slower than others with its progress. This front will waffle across the region on Friday and Saturday. With northwesterly flow aloft on the northeast side of the ridge, significant widespread rain is not expected despite the near-stationary front, but showers and thunderstorms will be possible each day. The position of the front each day will determine temperatures, with significantly cooler readings likely north and east of the boundary, while very warm readings should prevail south and west.