... A weak disturbance may provide a shower or storm across mainly northern areas late today and overnight. A decaying convective complex, and a following cold front, will bring a better chance for widespread showers and storms on Thursday. Drier and cooler weather follows for Friday and Saturday.
NEAR TERM /THROUGH TONIGHT/... High pressure crossing into the Central Appalachians is providing a dry air mass and a mostly sunny sky to the CWA this afternoon. Afternoon highs will climb well into the 80s areawide, and a few 90 degree readings are also expected.
A relatively weak shortwave will skirt the northern portion of the CWA late today and tonight. Scattered cumulus are already beginning to pop across the north, where instability and moisture are marginally better. Scattered showers and a thunderstorm or two are expected to remain mainly near and north of I-80 during the late afternoon and nighttime hours, where moisture will be a bit deeper. Little more than some mid and upper cloud is expected south toward the Pittsburgh area, with a mostly clear sky to the south. Fairly seasonable temperatures are forecast.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... The frontal boundary will continue to make very slow southward progress on Wednesday, getting a push from a mid-level wave that will cross the Upper Ohio Valley during the afternoon and evening. Much of the vorticity advection remains off to the north, but at least isolated convection seems possible along the boundary as it sinks across. Model soundings indicate decent instability, but mid and upper-level moisture become a bit more questionable with time. Nevertheless, any storm that manages to stand up could tap into that dry air and produce downburst wind. This activity will mostly dissipate with the loss of daytime heating.
As a shortwave dips into the Great Lakes Wednesday night, the models are pointing to potential MCS development in the Wisconsin vicinity Wednesday evening, with the complex possibly diving across Michigan and into Ohio by Thursday morning. Given the timing, severe potential from this system should be decreasing by the time it reaches our CWA, but PoPs will be needed from ongoing showers and storms. The path and timing of the MCS remains in question, but there is the potential for a decent amount of rain along the track Thursday morning. This complex will weaken considerably with time through the morning, but then another cold front trailing the MCS will then sink across the region, bringing further support for rain during the day as convection refires along the boundary. Depending on destabilization in the wake of the MCS, a severe risk exists mainly across the southern reaches of the CWA during the afternoon/evening as the front crosses. Enough deep-layer shear will exist to support a damaging wind threat in the strongest storms. Rain coverage will drop off overnight as the front exits.
Above-normal temperatures will continue through Wednesday, while expected clouds and rain should keep values closer to climatology on Thursday.
LONG TERM /FRIDAY THROUGH MONDAY/... Ridging will remain in place over the Rockies and the southern Plains into early next week. The main band of westerlies will generally remain just north of the CWA in this pattern, with any rain chances through the period confined to areas north of I-80. Overall, a dry pattern is anticipated. In the general troughing pattern, temperatures will remain just a bit below normal.