Area Forecast Discussion
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000 FXUS61 KPBZ 241813 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 213 PM EDT Wed Aug 24 2016 .SYNOPSIS... A couple of crossing disturbances will return rain chances to the Upper Ohio Valley Region for the overnight and Thursday. && .NEAR TERM /THROUGH TONIGHT/... High clouds have continue to stream toward the area today ahead of a fairly compact system easily discernible over northern Illinois at this hour. This system is attempting to track right into the apex of a mid-level ridge anchored over the Appalachians, which the models indicate will show little propensity of budging over the period. As a result, the best forcing for ascent will be shunted a bit to the north of the area as it attempts to track eastward. However, a gradual increase in layer moisture overnight toward morning combined with an increase in DPVA will allow for the return of shower chances overnight. With the increase in cloud cover as well as southerly flow in place over the area combined with much warmer temperatures this afternoon than we have seen in a couple days, a strong radiational cooling night is not expected. Due to the floor these aforementioned phenomena will place under temperature falls, lows generally straddling 70F seem fairly plausible. Fries && .SHORT TERM /THURSDAY THROUGH SATURDAY/...
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The northern zones are progged to be in a favorable environment to experience numerous convection Thursday as a front sags southward. Fueled by day time surface heating and increased flow aloft, some thunderstorms may reach severe criteria, but overall coverage and intensity should be marginal across the region as instability remains limited by very warm mid level temperatures. Precipitation chances are projected to wane on Friday as surface high pressure builds in the wake of a weak front. Given the strength of the upper ridge, southward frontal penetration is questionable, but will generally persist with a dry forecast through Saturday as per the latest deterministic trends as flow becomes zonal. Warm weather will continue as zonal flow across the northern ridge periphery shunts warm air across the region.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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Flow is expected to back to a southwesterly direction as an upper high enhances and shifts towards the Mid-Atlantic. As a result of the strengthening ridge, anonymously high surface temperatures and upper heights are predicted by ensemble models and have led to higher confidence in raising forecast temps early in the period. Overall, hot and humid conditions can be expected in the beginning of the long term until the passage of a shortwave on Monday provides some relief from the heat. POPs were maintained in association of the aforementioned shortwave as per the latest Superblend guidance.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... High clouds will continue to increase through the evening, even as diurnal cumulus fades. Showers will encroach from the west overnight, however coverage is questionable and restrictions from them also questionable due to copious coverage of high clouds. The forecast was built without visibility/ceiling restrictions with the best chance of showers and even a thunderstorm being during the daytime hours Thursday. Fries .OUTLOOK /THURSDAY THROUGH SUNDAY/... Periodic restriction chances should persist through Friday with the approach and passage of a cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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