Wisp Resort / McHenry

Summary

SYNOPSIS

... High pressure will continue to push offshore today allowing for warmer conditions. Light rain chances return Friday as an area of low pressure approaches from the Ohio River Valley. Additional waves of low pressure look to bring excess cloud cover and precipitation chances to the region this weekend into early next week.

NEAR TERM /THROUGH TONIGHT/... It's a wide range of temperatures this morning due to a very shallow, but sharp nocturnal surface inversion with the antecedent dry airmass (dewpoints in the teens) overhead. Temperatures range from 30s over the ridges/waters to teens and low 20s in the sheltered valleys. Skies remain mostly clear with some high level cirrus set to approach from the south heading into daybreak. Hi-res CAMS continue to paint the thickest cirrus along and west of the I- 81 corridor. Confidence in this occurring remains moderate based on hi-res model trends and current satellite observations of mid and high level cloud cover working north from the southwest VA/southern WV.

Outside of the high cirrus this morning, it looks to be a dry and much warmer day ahead as broad high pressure continues offshore. Highs today will range from the low to mid 50s across much of the region with mid to upper 40s over the mountains. Hi-res guidance pushes mid and high level cloud cover back into the area this afternoon and evening as moisture increases on south-southwesterly flow. The increase in cloud cover will continue tonight as a strong shortwave trough and associated low pressure system approach from the Mid-South/Ohio River Valley. With the added cloud cover expect lows in the mid to upper 30s. Valley locations will have a chance to decouple for a brief period of time overnight leading to lows in the upper 20s and low 30s. No precipitation is expected with residual dry air remaining in place as broad high pressure pushes further offshore.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... Synoptically, we are looking at a zonal upper level flow pattern with several embedded weak waves of shortwave energy to round out the workweek and into the weekend. The first wave comes in the form of an area of low pressure and it's associated front set to approach from the Ohio River Valley Friday. Most locations will start out dry Friday as it will take sometime for the atmospheric column to moisten. Shower activity will start west of the Allegheny Front Friday morning before pushing toward the metros mid to late afternoon. 00z deterministic/ensemble guidance has trended slightly slower which means the risk for a brief period of any wintry precipitation on the front end has decreased drastically. Even with that said, vulnerable sheltered valley locations west of the Blue Ridge could see some snow/sleet mixed at pending on when the precipitation arrives. No accumulation is expected with a quick changeover to rain showers as temperatures warm through the morning and afternoon hours. Any rain shower activity is likely to be light and short duration given most of the energy associated with this system will remain north of the area. Rainfall amounts will remain less than a quarter of an inch.

Friday temperatures will start in the low to mid 30s west of the Blue Ridge with upper 30s further east. High temperatures Friday afternoon will warm back into the upper 40s and low 50s with increased southwesterly flow. Breezy conditions will also return with south to southwesterly winds at 10 to 15 mph gusting up to 25 mph at times Friday afternoon and evening.

Shower chances decrease Friday night into Saturday as the best isentropic lift works north of the region. Southwesterly flow will continue aloft as broad upper level troughing remains over the central CONUS. At the surface, will be caught between the northern stream trough and an area of low pressure/warm front lifting northward from the Gulf Coast. The combination of these two features will keep a low end chance for showers in place over most of the forecast region with higher chances west of the Allegheny Front and to the south across the southern MD/northern neck of VA where better forcing resides. Cloud cover will also be in abundance with a notable warm surge as the warm front lifts in Saturday afternoon. High temperatures will push into the upper 50s and low to mid 60s. Lows Saturday night will fall into the mid to upper 40s and low 50s.

LONG TERM /SUNDAY THROUGH WEDNESDAY/... Showers seem likely Sunday-Sunday evening as heights fall across the region ahead of a negatively-tilted s/w trough moving across the OH River Valley and the northern mid-Atlantic and sfc low pressure develops overhead. Colder air begins to filter in Sunday night as NW flow strengthens as low pressure deepens offshore. Snow showers late Sunday night into Monday may accumulate several inches of snow across the higher terrain before shortwave ridging builds in briefly on Tuesday.

A second shortwave trough diving from the Central Plains into the OH River Valley Tue into Wed will reinforce the trough pattern across the East bringing temperatures back to slightly cooler than normal and a second and more significant round of snow showers/squalls across the Appalachian region Wednesday. This could also bring the first measurable snow, albeit light to locations east of the mountains. Conditions should begin to improve Wed night and the second half of next week as trough axis shifts east.