Area Forecast Discussion
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000 FXUS61 KPBZ 221544 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1144 AM EDT Tue May 22 2018 .SYNOPSIS...
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A cold front will bring showers and thunderstorms this evening some of which could be strong or severe. High pressure then provides a few days of dry weather. Unsettled conditions return during the holiday weekend. Above normal temperatures will continue.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Scattered rain showers will continue in portions of northern WV where a boundary will linger through the early afternoon. Elsewhere, expansive cloud cover will hold temperatures and initiation of afternoon convection in check. Highs will be a few degrees lower than yesterday, but the humidity remains. To our north and west, a cold front draped through the southern Great Lakes is spawning isolated convection near the south shore of Lake Erie and through northeast Indiana. The cold front will drag through the area this evening with support aloft in the form of a passing upper-level shortwave trough. Despite the aforementioned cloud cover, enough instability should develop under strengthening mid-level wind field to sustain deep convection. Thunderstorms developing through northeast Ohio this afternoon will move through the forecast area through this evening, possibly persisting into the early overnight hours. Some mid- level drying, evident on the morning ILN sounding, and developing DCAPE to the tune of ~800 J/Kg would suggest that damaging wind would be the primary threat this evening. Cannot, however, rule out the potential for large hail as the bulk of the CAPE is centered over the hail growth zone near 400-500mb. Thunderstorms should weaken by midnight as instability wanes, and only a few showers at most should remain along the southeast ridges overnight. Fog is a possibility, especially across the north, if clouds can clear a bit faster than expected. Temperatures will continue to run above normal.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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A pattern shift is in the works for the latter part of the week, bringing drier weather areawide. In the wake of tonight`s cold front, showers will have all but dwindled by Wednesday morning. Dewpoints will fall back into the mid 50s, allowing conditions to feel a little less muggy. From there, surface high pressure and ridging aloft will keep the forecast dry through Friday. Temperatures will steadily climb back up to well above average by Thursday and Friday, with higher humidity levels returning by the weekend.
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&& .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... Mid-level ridging will lead to continued dry weather into Saturday, and 850 mb temperatures climbing to around 16C point to high temperatures in the mid 80s across many areas into the first part of the weekend. Unsettled weather returns for the rest of the holiday weekend. Moisture gets pumped northward around a potential Gulf tropical system, and waves riding over the flattened ridge will provide support for several rounds of precipitation. Given the potential for high PWAT air and warm rain processes, there is some potential for at least isolated areas of excessive rainfall. However, at this distance, NAEFS anomalies and GEFS QPF M-climate do not point to anything highly unusual, and so will wait for further developments before raising any alarms. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... Occasional MVFR conditions are expected in showers through the morning as a warm front lifts N across the area. The showers should become isolated to scattered after sunrise, though some patchy MVFR cigs are expected as CU redevelops. A cold front is expected to approach and cross the region later this afternoon and evening, with another round of showers and thunderstorms. Maintained a VCTS mention in the TAFs until timing can be better determined. Cigs should drop to MVFR after FROPA as winds shift to the WNW. OUTLOOK... Restrictions are possible through early Wed as the cold front exits. Restriction potential returns with weekend low pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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