Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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649 FXUS61 KPBZ 300513 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 113 AM EDT Sun Jun 30 2024 .SYNOPSIS... Renewed showers and storms develop late tonight. A cold front moves across the region Sunday morning, with high pressure building in its wake to start the week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... KEY MESSAGES: - Scattered showers and possible storms through Sunday morning. ------------------------------------------------------------------- Latest (Overnight) Update... Minor adjustments made to temperature forecast overnight through early Sunday morning. Current temperatures are still in the upper 70s to around 80 at a lot of locations, and dewpoints across the region continue to hover in the low 70s. With little change expected in the latter conditions, expect low temps to remain several degrees above what guidance is suggesting (low 70s for most; upper 60s still possible in the ridges). The rest of the forecast remains on track. Previous discussions can be found below. Previous (Evening) Update... The latest mesoanalysis shows ML CAPE values decreasing across the region. Shear remains elevated, though with no significant forcing for ascent it appears the severe weather potential has diminished. Will let the current Severe Thunderstorm Watch expire at 10 PM. Another shortwave, and associated surface cold front, will approach the Upper Ohio Valley region late tonight. This should generate isolated to scattered showers and possible thunderstorms across the region. A few strong storms will be possible as the front approaches. Original discussion... PoPs have been updated to reflect latest expectations. Storms across nrn WV will continue for an hour or two as they translate ewd and across the mountains. Blowoff from storms near KILN also may eventually graze Muskingum County in OH. An upswing in storm coverage in the far srn zones (nrn WV to near the Mason- Dixon Line is increasingly probably late tonight/pre-dawn tomorrow, and may expand in coverage with approach and passage of the cold front Sun morning. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... KEY MESSAGES: - Cold front moves through Sunday morning. - A few storms may be strong along it south and east of Pittsburgh. - Drier air builds in with cooler temperatures. ------------------------------------------------------------------- The cold front itself then moves through Sunday morning and carries an additional lower confidence severe threat. Unfavorable mid to late morning timing with at least some degree of cloud cover around as even the lower end of the latest ensemble guidance indicates 40- 50% sky coverage through the morning hours lends less of a severe threat, though that said, can`t rule out some stronger storms capable of damaging wind southeast of Pittsburgh where a Marginal Risk (1/5) remains. We then finally get a push of drier air behind the front on Sunday afternoon and evening as high pressure builds across the Great Lakes and reinforces northerly flow in the wake of the boundary. Still a bit of discrepancy in the 12z guidance on the timing of the front; highs will be dependent on said timing as a quicker boundary could keep PIT in the upper 70s while a slower push could result in mid 80s. Either way, clouds will scatter into Sunday evening, though a passing upper wave looks to reinforce cloud coverage toward morning on Monday. Still, overnight lows will be refreshing dipping into the 50s for most, though some 40s are possible (50-70% chance) in the ridges and north of I-80. Dry weather continues with high confidence through Monday night as heights begin to rise and high pressure moves further east. Temperatures remain below average on Monday with ensemble probability <30% of highs topping 80 degrees. && .LONG TERM /TUESDAY THROUGH SATURDAY/... KEY MESSAGES: - Dry weather continues Tuesday with increasing temperatures. - Showers and thunderstorms return Wednesday and Thursday with another low pressure system. ------------------------------------------------------------------- Good agreement amongst the various ensemble clusters supports dry weather on Tuesday as ECONUS ridging builds. Temperatures begin to rebound as flow becomes more south of east and pushes highs back toward or a couple degrees above normal. By mid-week, the pattern becomes more unsettled as ensembles break the ridge down and low pressure moves by to our north. Deep southwest flow on Wednesday surges temperatures back to 5-10 degrees above normal, though timing of a cold front passage may throw a wrinkle in that. Ensembles show increasing deviation from the mean come Wednesday night through the remainder of the week, so confidence is lower, but a cold front looks to pass through sometime late Wednesday into Thursday returning shower and thunderstorm chances. Machine learning becomes more interested in severe chances by mid-week as the front pushes into a warm, moist airmass, so this will bare watching through the coming days. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... Scattered showers, with isolated thunderstorms south of PIT, will continue this evening as a shortwave trough crosses the Upper Ohio Valley region. The threat for thunderstorms elsewhere continues to diminish, with weak forcing for ascent. VFR is expected for much of the evening outside of any thunderstorms. Expect MVFR/local IFR cigs late tonight with low level moisture in place. In addition, scattered showers and possible thunderstorms are expected late tonight/early Sunday morning as a cold front crosses the region. MVFR will continue until mixing and dry advection lift cigs back to VFR by Sunday afternoon. Wind gusts should also increase after FROPA, with gusts to 20kt Sunday afternoon. .Outlook... Outside of early morning river valley fog, VFR is expected until a slow moving front sets up across the region Wednesday and Thursday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...MLB NEAR TERM...Cermak/Kramar/WM SHORT TERM...MLB LONG TERM...MLB AVIATION...WM