Area Forecast Discussion
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983 FXUS61 KPBZ 220519 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 119 AM EDT Mon May 22 2017 .SYNOPSIS... Drier conditions will return for Monday. They will be short- lived, however, as rain reenters Tuesday with the approach of Mid-Atlantic low pressure. && .NEAR TERM /THROUGH TODAY/... Meager instability remains along a weak frontal boundary moving across Ohio at this hour. Shear along the boundary seems sufficient to maintain scattered activity along it through the night as it emerges toward the ridges in the morning hours. Surface dewpoints fall off about 15 degrees along the front, so clearing should become fairly evident as the front passes through the morning hours. This will yield a much more comfortable environment going into the daytime on Monday. Even with the frontal passage, cold advection with the front is not particularly strong. Surface flow never really turns northerly at all, and the cold pool at 850 mb is shunted north of the area fairly quickly through the day. Thus, temperatures won`t really be cut back too much from recent days, and abundant sun will allow for insolation to work on the dry boundary layer yielding temperatures straddling 70 degrees yet again. Fries && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... Conditions should improve by Monday afternoon under building high pressure and last through at least the start of Tuesday. The models continue to differ on the evolution of low pressure moving across the Tennessee valley on Tuesday. At this time, have opted to bump PoPs up based on some of the newer guidance and ensembles, as now the GFS seems to be the outlier. Departure of this low will be quickly followed by yet another system, again, which is being resolved a little differently between deterministic models. Opted to stay close to a model blend for midweek based on the uncertainty. Temperatures are expected to be near seasonal averages through the period. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Upper trough and embedded shortwaves will start to shift eastward toward the end of the week, but it`s influence should maintain at least low chances for precipitation through the period based on model consensus. Temperatures will generally stay just below seasonal averages through the start of the weekend. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... Scattered showers with isolated thunder has been slow to move across the area early this morning. The scattered nature of these showers will result in nothing more than a temporary visibility restriction, if that. Otherwise, guidance has been bullish on dropping ceilings in the pre-dawn hours as a cold front traverses the area. Outside of the far northern port of FKL, these drops have not been realized. Still think it`s possible to see a window of low MVFR or perhaps temporary IFR with the frontal passage, but am chipping away the onset time by a few hours with the 06z TAF issuance. Any restrictions that do accompany the cold front will improve quickly near or just after daybreak Monday as much drier air moves in. Southerly winds currently across the area will shift quickly with the passage of the front. Surface flow will then generally stay west-northwesterly through the remainder of the TAF period. .Outlook... The next chance for widespread restrictions and precipitation is expected Wednesday night into Thursday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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