Wisp Resort / McHenry

Summary

SYNOPSIS

... An active pattern will continue through mid-week as multiple disturbances pass through the area. A cold front will move through toward the end of the week.

NEAR TERM /THROUGH TONIGHT/... A cold-air wedge remains in place to the east of the Appalachians. Warm/moist advection riding over this wedge is allowing for precipitation over most of our CWA. During the past hour, precipitation over Northeast MD and the northern Chesapeake Bay has been diminishing, while the precipitation over central MD and eastern WV has been holding its own as it moves toward central PA. There has been additional development of heavier showers over north-central and central West Virginia during this same time stamp as this is the area of better instability. As time goes on into the afternoon, we expect north to northeast winds to become southeasterly at light to modest speeds. Also, our temperatures should climb into the middle to upper 60s by late afternoon depending on how much clearing. To the west of the Blue Ridge, temperatures should climb into the lower to middle 70s. Should we get some clearing and additional low level warmth and moisture this afternoon, then we could see additional showers and perhaps a couple of thunderstorms east of the Blue Ridge. The greatest chance for a thunderstorm during the mid- late afternoon hours looks to be between the Allegheny Front and I- 81.

Conditions should dry out overnight, but skies should remain mostly cloudy. If any breaks in the cloud cover are able to develop, fog may develop overnight, given weak low-level flow and ample moisture in place at low-levels following ongoing rainfall. Temperatures will remain mild overnight, with lows in the upper 50s to mid 60s.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Previous discussion... A largely convectively generated disturbance (by ongoing storms across the Southern Plains) will drift through the Tennessee/Ohio Valleys toward the area on Monday. The day should start out dry, but mostly cloudy for most. As the disturbance drifts toward the area, low-level moisture will be drawn northward into the area in southerly flow as greater mid-upper level moisture simultaneously advects into the area aloft. Daytime heating will allow temperatures to climb into the upper 70s and lower 80s, which when coupled with the increasing moisture will lead to the development of some surface based instability. Showers and thunderstorms appear possible Monday afternoon, with the greatest coverage expected to be across the Central Shenandoah Valley into Central Virginia, where low- level convergence is expected to be maximized. Model soundings show around 1000 J/kg of MLCAPE, along with relatively moist profiles and weak flow through the lower half of the troposphere. Such an environment could lead to slow moving, heavy rainfall producing storms, especially from the Shenandoah Valley into Central Virginia. 00z CAMs show isolated areas of 2-5 inches of rainfall across those locations Monday afternoon, which potentially raises concerns for flash flooding. With the disturbance forcing the precipitation being largely convectively generated, that makes predictability a bit lower than normal at this time range, so things could potentially change. However, we'll continue to keep an eye on the potential for heavy rainfall Monday afternoon.

Additional showers and thunderstorms appear possible again on Tuesday as a disturbance tracks into the Great Lakes. Much like Monday, high temperatures are expected to reach into the upper 70s and lower 80s. Soundings again show relatively saturated profiles along with some surface based instability, so storms may once again be heavy rainfall producers.

LONG TERM /WEDNESDAY THROUGH SATURDAY/... Rain and thunderstorm chances will continue by Wednesday, with an approaching cold front from the west. The precip chances will increase from west to east later in the day on Wednesday with highs in the mid to upper 80s for the lower elevations and 70s for the mountains. Winds out of the west will be gusting to 15 to 20 knots throughout the afternoon. Precipitation chances increase overnight Wednesday and through the day on Thursday as the front continues to approach the area. Given the increasing instability ahead of the front, a few isolated strong to severe thunderstorms may be possible with the frontal passage on Thursday. Additionally, some isolated instances of flooding will be possible with the continuous prolonged batches of precipitation over just a few days. Still a lot of uncertainty pertaining to timing, intensity and antecedent conditions. Highs on Thursday will climb into the upper 70s to low 80s for most areas.

Behind the front on Friday, precipitation will likely linger around with highs in the 70s for the lower elevations and 60s in the mountains. Northwest winds will remain elevated with gusts getting into the 15 to 25 knots range, with the higher amounts along the higher elevations. Lingering light showers may persist into the weekend with highs in the mid to upper 60s for most areas with 50s in the mountains.