... An upper-level trough will remain overhead through tonight before moving off to the northeast Thursday. High pressure will build north of the area for later Thursday into Friday. Low pressure may impact the area this weekend into early next week. For the latest information on Ian, refer to the National Hurricane Center (hurricanes.gov).
NEAR TERM /THROUGH TONIGHT/...
A potent shortwave-trough will move across the area this afternoon and trigger few-sct showers across the mountains potentially reaching as far east as the I-81 corridor in western MD and eastern WV. These should be gone with loss of heating early this evening.
An upper- level trough will continue to build overhead while surface high pressure approaches from the north and west. A northwest flow will continue, and with the trough overhead it will be cool for this time of year. Max temps will range from the 40s and 50s in the Allegheny Highlands to the 60s and lower 70s for most other locations.
Most areas will be dry, but there will be some instability underneath a subsidence inversion, thanks to the upper-level trough. Scattered showers are expected in the Allegheny Highlands, especially late this morning into early this evening. A few isolated showers may spill east of the mountains into northern MD/eastern WV/northern VA this afternoon/early evening. Any precipitation amounts will be light.
A sct/bkn cu deck will overspread the area from northwest to southeast this morning into this afternoon in response to the digging upper-level trough.
The trough will remain overhead tonight while high pressure continues to build toward the area. Dry and cool conditions are expected. A thin stratocu deck and light north to northwest wind should prevent any widespread frost from developing in the Allegheny Highlands.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... The upper-level trough will move away from the area Thursday while high pressure builds to the north. Dry conditions are expected along with some sunshine. Highs will be in the 60s to lower 70s for most areas (50s in the mountains). Dry and cool conditions will persist for Thursday night with high pressure nearby.
Ian will most likely track northward near the southeast coast Friday before moving further inland Friday night. Refer to the National Hurricane Center for the latest information regarding the track of Ian. Tropical moisture and warm air will overrun cooler air in place, resulting in increasing clouds Friday along with increasing chances for rain from southeast to northwest late Friday through Friday night.
LONG TERM /SATURDAY THROUGH TUESDAY/... An increasingly likely wet start to the long term period as a result of future remnants from Hurricane Ian. Synoptically, a large area of high pressure over the Northeast will play a pivotal role in the progression of the incoming low pressure system to the south.
Should the latest forecast solution become realized, isolated instances of flooding as a result from moderate to heavy rainfall are possible, mainly south of the metropolitan areas where confidence is higher for heavier rainfall. Precedent dry soil conditions may be beneficial in this instance to relieving the flood threat to a more isolated nature. The rainfall will most likely hang around through Monday before slowly exiting toward the middle portion of next week.
With any complex system (i.e, a hurricane), uncertainties will remain heading closer to the actual event given the variability of the storms progression before reaching a point as well as other meso/micro/synoptic-scale forcing that may play a role. As always with any tropical events, please visit hurricanes.noaa.gov for the latest tropical forecast via the National Hurricane Center.
Temperatures for the long term will hover around at or just below average for most of the area in terms of highs (60s for most, 50s for higher elevations with localized 40s late in the weekend).