Area Forecast Discussion

WHAT HAS CHANGED

Minor changes to timing of rain were made today and tonight, with minor adjustments to the weekend forecast.

KEY MESSAGES

1) Warm today, then rain returns this afternoon and evening into early Thursday.

2) Cooler Friday into the weekend

DISCUSSION

KEY MESSAGE 1... A closed low will continue to drift across the Upper Midwest today. Southerly flow ahead of this trough, and mixing, should result in high temperatures around 15 to 25 degrees above average, with the warmest readings across PA and nrn WV. Some sites could approach record highs before clouds thicken through the day ahead of an approaching shortwave. This shortwave (and associated cold front,) ahead of the main upper low, will approach the region in SW flow aloft this afternoon, crossing the region this evening into early Thursday. Moisture and ascent with the wave, assisted by a jet aloft, should result in rain overspreading the region from W-E this afternoon through this evening. A low level jet and minimal elevated instability could also result in an isolated thunderstorm.

Rainfall amounts are expected to range from 0.25 to 0.5 inches for most areas. Low end QPF (10th percentile) is around 0.10, with high end amounts (90th percentile) around 0.8 inches.

The shortwave and surface front should exit the region Thursday morning, with decreasing rain chances. Temperatures will be cooler than recent days, though still around 10 degrees above average.

KEY MESSAGE 2... Model ensembles indicate the upper low will open into a trough Thursday, as it tracks across the Great Lakes region. Another deepening upper low is then progged to drop SE through the trough, reaching the Great Lakes region again on Friday. This low should continue eastward across the Upper Ohio Valley region through Saturday. This should spread areas of rain across the region again later Friday into Saturday. 850 mb temperatures are also progged to drop to between 0 and -2 deg C during this time according to the latest ensembles. This should bring temperature back down to near seasonable levels over the weekend.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Increasing mid and high clouds are expected through the day ahead of an approaching shortwave trough and surface cold front. The front will cross the region from W-E this evening through early Thursday, with rain and MVFR restrictions overspreading the region from W-E. These conditions should begin at ZZV by mid afternoon, and at PIT by evening. Rain and MVFR/patchy IFR restrictions are likely to continue overnight with the crossing front.

Outlook... Restrictions should continue into early Thursday as the front completes its passage. After some improvement later Thursday into Friday, restriction and rain potential returns later Friday through Saturday with a crossing upper trough. Cold NW flow behind the trough could maintain cig restrictions into Sunday.

PBZ WATCHES / WARNINGS / ADVISORIES

PA...None. OH...None. WV...None.