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Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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506 FXUS61 KPBZ 251700 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 100 PM EDT Tue Jun 25 2024 .SYNOPSIS... Remnants of a mesoscale convective system may impact the region after 1pm today. Heavy rain showers and sub-severe wind gusts may occur. The threat for strong storms increases Wednesday with a new disturbance. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - An upstream disturbance is expected to impact the region early afternoon into the early evening. - Periods of heavy rain and lightning may occur after 1pm for eastern Ohio. - Wind gusts along the line of showers and storms may range from 30mph to 40mph. ------------------------------------------------------------------- A mesoscale convection system (MCS) continues to dive south, within an elongated ridge, across the Great Lakes early this morning. Noted impacts over northern Indiana and northwest Ohio include small hail and wind gusts ranging from 30mph to 45mph. Velocity measurements from surrounding radars over the Midwest indicate a low-level jet of 35mph to 40mph between 1,000ft to 2,000ft. Remnants of this MCS will likely start to impact our region over the next 2 to 4 hours. However, the overall intensity will rapidly dissolve with time given warm air associated with the ridge. A quick period of heavy rainfall rates (1 to 2 inch per hour rates) and 30mph to 40mph wind gusts may observed with the downdrafts. With increasing cloud coverage from outflow of the MCS and precipitation chances, temperatures north of I-70 will likely trend near average. Areas south may trend 5 degrees above average. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Showers and thunderstorms are more likely Wednesday with a crossing front. - Severe storms and flooding will be possible. ------------------------------------------------------------------- A trough and associated cold front cross the region Wednesday, with a late afternoon/evening FROPA. 25th to 75th percentile QPF for KPIT ranges from 0.20" to 0.8", and with convection there will always be a rather large range so this seams reasonable. Similar to Tuesday, the Wednesday convective setup will be modulated by the evolution of Tuesdays convective cold pools. In any case, showers and storms are more likely. SPC is currently carrying a slight risk as far west as PGH and marginal elsewhere, with the primary risk being damaging winds. SPC also shows a 5% and 2% for hail and tornados respectively which lines up fairly well with the latest 00Z CSU machine-learning probabilities. WPC has the entire region under a marginal for flooding. && .LONG TERM /THURSDAY THROUGH MONDAY/... KEY MESSAGES: - Dry weather Thursday through Friday. - Near normal temperatures Thursday, before a late week warmup. - Shower and thunderstorm chances return for the weekend. ------------------------------------------------------------------- In the wake of Wednesday`s front, temperatures return to normal and dry conditions resume as high pressure builds in across the region. A warming trend in temperatures is forecast Friday and into the weekend as heights gradually rise, reaching about 590-592dm by Saturday. Ensembles show about a 50% chance in general of highs hitting 90F on Saturday. There`s a good chance most locations will see apparent temperatures back in the 90s with Tds back up in the upper 60s / low 70s. Showers and thunderstorm chances return with the increased instability and another frontal system Saturday and Sunday. Dry conditions and near to slightly above normal temperatures are forecast early next week as high pressure resumes control. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... An MCS will continue to weaken/move SSW of the region this afternoon, with low probability for thunderstorm and moderate rain shower impact at ZZV. Convective cirrus and VFR condition is favored the rest of the afternoon and evening period as subsidence maintains a stable environment. An upper level shortwave will approach the area late tonight into Wednesday with an associated surface cold front. Confidence is high that this wave will help foster increased shower and thunderstorm coverage between 15z-00z Wednesday. Confidence is significantly lower on timing and progression of convection starting as early as 09z. Available convective modeling shows a large range of storm evolutions through this period as they struggle to handle the altered environment the current Ohio MCS is causing. TAF leans a bit into HRRR and HRW ARW modeling given better handling on current weather; but variability in outcomes for both storms and area restrictions is high. .Outlook... Showers and thunderstorms will taper off (with longer delay in restriction improvements) with cold FROPA Wednesday evening. High pressure and rising heights aloft is favored to support VFR and dry weather Thursday/Friday. The next upper level shortwave and surface cold front will increase thunderstorm and restriction chances Saturday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Hefferan NEAR TERM...Hefferan SHORT TERM...88 LONG TERM...88 AVIATION...Frazier