A Mesoscale Convective System will impact parts of our region through early Saturday morning. Multiple fronts will impact our region through Tuesday. High pressure returns during the middle to later parts of next week.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Mostly clear skies are being reported for the all of our region this afternoon as high pressure has settled off-shore. Winds remain mainly out of south to southwest with afternoon temperatures trending toward the mid to upper 80s.
A MCS currently affecting parts of eastern Ohio, western PA and western WV will slowly approach our region later this evening and into the overnight periods. This system will be capable of producing showers and strong thunderstorms and may lead to localized heavy rain or an isolated SVR threat. A deep later of westerly winds will likely limit the threat for showers and thunderstorm further east of the Allegheny front. CAMs generally have the MCS slowly dissipating as it moves further eastward but I can rule a isolate shower or thunderstorm reaching the western parts of the Blue Ridge Mtns. The main threat window will be between 3Z and 9Z on Saturday and focused over western MD and along the MD/PA border. Overnight lows will be very mild in the mid to upper 60s to lower 70s.
SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
An upper level trough will drop down into the northeast US on Saturday. A surface low associated with the upper trough will pass through the upper parts of the NE US with its corresponding front dropping into parts of NY. Our region will remain on the warm side of the front which will allow for temperatures to trend up into the mid to upper 90s on Saturday.
The threat for thunderstorms on Saturday have decreased over the past few days. The upper trough has trended further northward while an upper jet moving through PA remains disconnected from a secondary shortwave dropping into our region Saturday afternoon. The combination of CAPE values hovering around 2000-3000 across the MD/PA border along with modest shear and a shortwave moving through Sat afternoon may lead to areas of strong thunderstorms or a localized convective line. CAMS overall have trended downward with the thunderstorm coverage and I believe the main threat area will be focused along the MD/PA border which will be near the best shear. The threat for showers and thunderstorms should start to taper off after sundown with only isolated showers or storms possible into Sunday morning. Overnight lows will be mild once again in the mid to upper 60s to lower 70s.
Sunday will likely start off dry but as diurnal heating begins, temperatures will rise up into upper 90s. CAPE values will likely rise above 2000 once again, but the upper jet is expected to weakened leading to much lower shear values throughout the layer. The lack of good forcing and shear will limit the widespread thunderstorm threat but the combination of hot and humid conditions along with decent lapse rates will allow for pop up showers and thunderstorms. As CAPE values will be close to 3000 on Sunday, I can't rule out a localized strong thunderstorm threat due to pulse storms. The threat for thunderstorms should taper off after diurnal heating shuts off with only a small chance for storms Sunday evening mainly in the southern parts of our region due to an approaching low.
LONG TERM /MONDAY THROUGH FRIDAY/...
Generally good agreement amongst the latest guidance suite in regards to the long term period. Confidence is increasing for the remnants of a tropical system originating in the Gulf of Mexico to track just to our south and east, away from the CWA on Monday. If this trend remains the same over the next few model run cycles, then don't foresee any hazardous impacts to the region. If the track shifts slightly more north and west, then the potential for heavy rainfall across the region would be the main hazard. However, the first scenario seems more likely at this point in time, given the advancement of a cold front which is slated to cross the region late Tuesday into Wednesday.
Hot and humid conditions continue on Monday and Tuesday with temps in the low to mid 90s for most and dewpoints in the upper 60s to low 70s. Even if the remnant low passes offshore, the unstable airmass would still poise the chance for scattered afternoon showers and thunderstorms Monday.
However, the bigger threat is Tuesday afternoon and evening as the front advances further south. A much cooler and drier airmass is present on the backside of the boundary. If the timing of the front remains the same, given the drastic differences in air masses, ample moisture, instability, 0-6km shear, and lift, would signal a potential severe weather event across the region. Flooding or flash flooding could also become an issue given high PWs.
Cooler and drier conditions are expected for the middle and later portions of next week as high pressure regains control of the region. However, heat and humidity may begin to build back into the region once again towards next weekend.