Massanutten Resort / Harrisonburg

Summary

SYNOPSIS

... Showers and thunderstorm chances continue through Thursday with multiple waves moving through the Mid-Atlantic. A strong cold front will bring increased chances for severe and flooding impacts Thursday into early Friday. Precipitation chances decrease behind the front going into the weekend with cooler temperatures and high pressure nearing the Mid-Atlantic.

NEAR TERM /THROUGH TONIGHT/... Precipitation from the decaying convection across the Ohio Valley will continue to slowly move into the area this morning. The strongest cells look to stay further north of the area into PA. Nonetheless, have the chance for some showers and an isolated thunderstorm to approach the northern half of the area this morning, mainly before 9-10 AM. After that, conditions improve with even some periodic breaks in the clouds. Downsloping flow coupled with subtle subsidence in the wake of the decaying MCS may keep the overall threat for scattered thunderstorms down today.

There still remains an isolated threat for a few thunderstorms, mainly across the southern most parts of the area in central VA and southern MD later this afternoon. Essentially, if a storm is realized, then there could be some strong to severe characteristics to it given the convective parameters it will have to work with. Main threats with any of these storms will be damaging winds and large hail. With the downsloping flow in place, expect temperatures to rise into the mid to upper 80s across most areas aside from the mountains (mid 70s). Some lower elevations may flirt with 90 degrees, especially if enough breaks in the clouds occur. So, mainly a fairly dry afternoon and evening with just isolated chances for a few showers and thunderstorms, mainly across central VA and southern MD.

By tonight, clouds will increase from the west ahead of the approaching cold front moving in from the Ohio Valley. Rain chances will increase from west to east, especially after midnight, and continue through the night and into Thursday morning.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Increasing showers and isolated thunderstorms will continue Thursday morning ahead of the cold front passage. Expect overall QPF to be 0.50 to 1" with localized higher amounts, especially in heavier downpours and thunderstorms. Isolated instances of flooding will be possible, given the anomalously high PWATs coupled with antecedent moist conditions over the last week, especially across areas along and west of the Blue Ridge Mountains. A fairly sharp instability gradient may develop east of the Blue Ridge just ahead of the cold front Thursday afternoon. There is some uncertainty with this given any earlier convection/cloud debris from early convection late tonight into early Thursday. Should there be a lull with increasing breaks in the clouds, then some thunderstorms may develop and become strong to even severe. Main hazards will be damaging winds along with large hail of 1 inch diameter or greater as a result of steeper lapse rates. The best chances for thunderstorms will likely be across the VA Piedmont into southern MD. Afternoon highs will be in the upper 60s to low 70s across the MD/PA border, with low 80s further south across central VA.

Showers and isolated thunderstorms will linger early Friday, with showers continuing throughout much of the day as a result of the departing low pressure system off to the north. Cannot rule out an isolated thunderstorm Friday afternoon. Highs will cooler as a result of northwest flow, with mid to upper 60s across most areas with even mid 50s across the Allegheny Front. NW winds will be gusting 20 to 25 knots during the afternoon on Friday, with higher gusts possible along the ridges.

LONG TERM /SATURDAY THROUGH TUESDAY/... Longwave troughing will remain in place across the eastern US this weekend. On Saturday we'll start the day off between one shortwave departing offshore, and another digging down the backside of the longwave trough into the Ohio Valley. The latter shortwave will pass overhead Saturday night into the day Sunday.

Conditions should start off mostly sunny on Saturday within the subsidence behind the departing shortwave. Clouds and eventually showers will be on the increase as we progress through the afternoon as large scale ascent ahead of the next shortwave starts to overspread the area. Chances for showers will continue through Saturday night and into the day Sunday as the upper trough axis moves overhead. High temperatures this weekend are forecast to reach into the upper 60s and lower 70s, while low temperatures will generally be in the 40s to lower 50s.

Upper troughing will progress off to our east early next week, allowing heights to start rising aloft. Such a pattern will lead to drier conditions and a warming trend in temperatures. Highs are expected to reach into the low-mid 70s on Monday, and into the mid- upper 70s on Tuesday.