Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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773 FXUS61 KPBZ 020457 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1257 AM EDT Sun Jun 2 2024 .SYNOPSIS... Showers will return to the area late tonight into Sunday with crossing low pressure. Above normal temperature and low probability, low coverage showers and thunderstorms are favored thereafter until the next system arrives mid to late week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... KEY MESSAGES: - Dry weather continues through this evening before rain moves in from the west overnight tonight. - Lows around 10-15 degrees warmer than Friday night. ------------------------------------------------------------------- The forecast remains on track this evening as upper level cloud coverage increases from the west with moisture advection ahead of a weakening shortwave. With plenty of dry air below 400 mb the 00z PIT sounding, precip may struggle a bit at onset until saturation can occur... Mostly light showers will arrive late tonight and Sunday morning ahead of the shortwave. Latest model trends have continued the slower trend of showers putting onset of rain in the eastern Ohio zones most likely after midnight and into the Pittsburgh metro near sunrise Sunday. Stable overnight conditions and marginal shear should preclude lightning development. Warm advection, increasing moisture, and overcast conditions will keep area temperatures 10-15 degrees warmer than last night. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... KEY MESSAGES: - Showers and low probability thunder expected Sunday before tapering off during the evening. ------------------------------------------------------------------- The weakening shortwave trough will cross the region on Sunday, eventually pushing an associated surface cold front through by Sunday evening. Showers will progress across eastern Ohio during the early morning hours, then into and across western PA during the morning and afternoon hours. Excessive cloud cover should limit instability. Coincident with weak shear, this will limit thunder potential and minimize storm strength/severe potential. The lack of strong surface forcing and diminished upper support will also lead to more scattered coverage. Though the occasional brief heavy downpour remains possible, these factors will keep the flooding threat minimal, and some locations may see little to no rain. Dry weather should return by Sunday night with the loss of daytime heating and exiting of the shortwave/weak front. Any lingering overnight showers will be confined to upslope Laurel Highland zones. The lack of notable dry advection behind the system could make fog a potential overnight impact, depending on the degree/quickness of cloud clearing. Rain and overcast conditions should keep Sunday temperatures on the cool side, with most of the area in the upper 60s/lower 70s during the afternoon. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... KEY MESSAGES: - Low probability/low coverage showers and thunderstorms with above normal temperature Monday and Tuesday. - Increasing precipitation chances accompany a mid to late week low pressure system that will cause falling temperature. ------------------------------------------------------------------- Subtle ridging stretching from the lower Tennessee River Valley to the upper Ohio River Valley Monday is likely to promote dry weather and slightly above average temperature. The probability for showers and thunderstorms should be low and generally confined to the higher terrain where better moisture and terrain convergence may lead to an isolated afternoon storm. Little change in the broad synoptic flow is expected for Tuesday, which will promote above-normal temperature and dry weather. However, it is becoming more likely that rain chances with the next system will begin as early as Tuesday night into Wednesday morning. Weather for the remainder of the week will likely be under the influence of a large, elongated stacked low pressure system meandering across Manitoba and Ontario into the Great Lakes. Ensemble means favor increasing large scale ascent/forcing for our region on Wednesday, promoting more widespread showers and thunderstorms Wednesday into Thursday, likely most focused along/ahead of an associated cold front crossing on Thursday. Lingering low pressure across the Great Lakes/Ontario/Quebec into the weekend will likely promote periodic showers and thunderstorms with a downward trend in temperature. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... The approach and passage of a weak upper level shortwave trough will foster areas of light rain this morning that become more scattered showers during the afternoon before it exits this evening. Probability for lightning never exceeds 20 percent, and thus no lightning is mentioned in TAFs. VFR conditions are favoring at all terminals through 12z (8am), with only 30 percent probability of MVFR conditions at KZZV. After 12z, uncertainty increases in timing of potential restrictions; ensemble probability never rises above 50 percent for MVFR cigs at KPIT until the end of the TAF period while deterministic guidance suggests an 16z onset and persistence thereafter. The most likely outcome is periods of VFR mixed with MVFR throughout the afternoon and evening hours. Depending on boundary layer moisture and clearing of residual stratocu, fog and/or low stratus may develop Monday morning. However, variability on potential outcomes for that period remains high. .Outlook... Upper riding and surface high pressure will support a return to VFR conditions by Monday afternoon with a dissipating field of diurnal cu. The next low pressure system is favored to arrive Wednesday afternoon and evening and promote fairly widespread showers and thunderstorms. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Rackley/Frazier NEAR TERM...Rackley/MLB SHORT TERM...Rackley LONG TERM...Rackley/Frazier AVIATION...Frazier