... High pressure will weaken and move south of the area through Wednesday night, then move offshore Thursday into Friday. The remnants of Beta will likely pass to the south while weakening Friday into Saturday. A couple cold fronts are expected to approach from the Great Lakes and Ohio River Valley late in the weekend into early next week.
NEAR TERM /THROUGH TONIGHT/... A deep low and Teddy are interacting over the open Northwest Atlantic Ocean resulting in an impressive cyclone moving toward the Canadian Maritimes. Meanwhile, high pressure centered over the central Appalachian Mountains is slowly weakening and drifting southward. Northwest flow between the two has been fairly light today (around 10 mph), with a bit more of a breeze toward the Chesapeake Bay. Winds will likely hold steady or may even tick up a few miles per hour this evening especially east of the Blue Ridge Mountains as the gradient tightens due to the deep low offshore making its closest approach (several hundred miles to the east of DC/Baltimore).
Subtle warm/moist advection coupled with a steady light wind are expected to keep temperatures milder tonight than in previous nights, generally in the 40s to lower 50s, precluding any widespread frost concerns.
HRRRX cross sections/progs and upstream satellite continue to show smoke moving into the region this evening in the middle and upper levels of the atmosphere. This is expected to create a hazy appearance to the sky especially as the night progresses.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Northwesterly flow aloft will continue to usher some of the elevated wildfire smoke through the region Wednesday. While this should have no impact on surface visibilities, skies will likely continue to appear more hazy in nature. With the parent surface ridge weakening and peeling back toward the Tennessee Valley, the area will be coming off a milder overnight. The expected west to west-northwesterly downsloping flow is forecast to raise temperatures closer to climatology for Wednesday. Highs in the upper 70s are forecast for much of the region which is a couple degrees below much of the guidance given the potential for smoke to reduce solar insolation. The recent HRRRX smoke loops show the highest concentrations displaced to the south by late Wednesday, but additional upstream smoke could enter the picture the following day.
For Wednesday night, minimum temperatures may further come up as high-level moisture moves in from what is currently Tropical Depression Beta. There will likely be additional clouds into Thursday as a shearing shortwave approaches the central Appalachians. Highs should generally top out again in the upper 70s. A few isolated showers are possible into the overnight hours across southern portions of the Potomac Highlands and Shenandoah Valley.
LONG TERM /FRIDAY THROUGH TUESDAY/... High pressure will sit offshore Friday as the remnants of Beta track northeastward. Guidance has continued to keep the bulk of the moisture to our south, mainly over the southern VA/NC. For our CWA, clouds will dominate much of the day Friday with chances for showers increasing during the late afternoon/evening hours. With the high positioned offshore, Beta's moisture will be slow to exit the region. Therefore, have kept PoPs elevated through Saturday as showery periods are expected to continue into Saturday night.
A weak cold front will likely push Beta's remnants offshore, as high pressure briefly returns to the region Sunday. Thereafter, the pattern becomes a bit more active as a H5 low over southern Canada induces a deepening trough over the Midwestern US. As a result, a secondary cold front will move through the region late Sunday night into Monday, resulting in the possibility for another round of showers. There could even be some convective activity during this time given the uptick in humidity and ample wind shear.
Dry conditions look to briefly return Tuesday, before another cold front approaches the region by mid-week.