


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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534 FXUS61 KPBZ 161149 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 749 AM EDT Thu Oct 16 2025 .SYNOPSIS... Frost and freeze potential continues early Thursday morning and again overnight Thursday night. Dry conditions with gradual warming of temperatures expected through Saturday before widespread rain and gusty wind arrives with a cold front on Sunday. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Dry with areas of frost early this morning - Frost/freeze threat again Thursday night --------------------------------------------------------------- Surface high pressure meandering over the Great Lakes region continues to provide dry weather locally. Dew points are running much lower tonight than they were 24 hours ago, and with clear skies overnight, this should allow for efficient radiational cooling and potential frost development. There still is a bit of an established pressure gradient on the periphery of the high, so it`s possible that we maintain a light puff of wind overnight that prohibits complete bottoming out of temperatures but likely still enough for frost. Thus, a Frost Advisory remains in effect through 9am for most of the area save southeastern OH and outside of the WV ridges. Low level flow out of the north on Thursday will promote weak cold advection and the cooler Canadian airmass will settle in locally. Heights will remain largely the same as we`re wedged between a ridge to our west and closed low to our east in a mid-level omega block. Despite plentiful sunshine, high temperatures will hold a few degrees cooler than Wednesday right around or a touch below normal. Another night of frost/freeze potential expected Thursday night now with the core of the high closer overhead. Similar conditions to Wednesday night will be the result with higher confidence in calmer wind and colder overnight lows. The probability for the vast majority of the area to see frost is high at 60-100% (lowest in the urban areas). Freeze potential is higher as well with even lower dew points allowing for a lower floor, though interestingly, the HREF is not that excited for <32F with only a 20-40% chance north and east of Pittsburgh likely owing to its progged slightly elevated wind. Given the ongoing frost headlines Thursday morning, will allow the next shift to make the final call on Thursday night`s frost/freeze headlines so as to not confuse messaging. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... KEY MESSAGES: - Well above normal temperatures for the weekend - Scattered showers possible Friday night - Cold front passage Sunday offers higher rain chances and windy conditions ---------------------------------------------------------------- We`ll finally get some mid-level height rises locally as the ridge axis shifts eastward. Surface high pressure remains situated overhead and plenty of subsidence will keep dry conditions in place, though clouds will be on the increase from northwest to southeast through the daytime hours as some increase in mid and upper level moisture rides around the ridge. We`ll bring some warm advection/weak shortwave driven rain shower chances in late Friday into very early Saturday, but this shouldn`t amount to a whole lot with probability for >0.10" less than 25%. Saturday will be a transition day of sorts as a more complex pattern begins to take shape. A trough deepens over the central CONUS and pushes the narrow upper ridge over the eastern seaboard eastward over the Atlantic. A rather potent shortwave ejects eastward from the central Rockies during the day Saturday, traversing the Plains and reaching the Mississippi Valley overnight Saturday into early Sunday morning. Meanwhile, a surface low develops in the IA/WI/IL vicinity, which rapidly deepens and lifts northeast towards the Great Lakes, eventually becoming vertically stacked beneath the parent shortwave. As all of this occurs, it causes deep-layer southwesterly flow to strengthen downstream over the Ohio Valley and lower Great Lakes, which in turn brings moisture and unsettled weather back to the local area Saturday night through Sunday night. This will also result in a warming trend for temperatures Saturday and Sunday, with highs climbing into the low 70s each day. Sunday`s forecast becomes more interesting with a dynamic system bringing a two-fold threat. First, the stacked low moves closer in proximity to the local area as it crosses the Michigan lower peninsula and southern Ontario, which will cause the pressure gradient between it and a broad surface high centered off the southeastern U.S. coast to tighten. In addition, ensembles suggest the deep-layer flow to be quite strong as expected this time of year with around a 50% chance for 925 mb wind to exceed 35 knots which forecast soundings suggest will be easily mixed down to the surface. This will result in an uptick in non-convective winds. Latest probabilities for max wind gusts exceeding 30 mph on Sunday are have increased notably across the entire area with 80-100%, while probabilities for max gusts exceeding 40 mph have followed the same trend up to 40-70%. The second hazard will be showers and thunderstorms associated with this system. A cold front will pass through sometime on Sunday, though latest ensemble clusters still show a very low confidence pattern with the majority of uncertainty stemming from a timing issue with the parent trough. There`s about an even split between those members who suggest it`s quicker and through the area Sunday afternoon while the others hold it back until later Sunday evening. This evolution will impact frontal passage timing and potential thunderstorm development. This will be a high shear/low CAPE setup with mean NBM SBCAPE around 200-400 J/kg and 90th percentile values (contingent on any low probability scattering of clouds) sneaking up as high as 600 J/kg. Deep layer shear will be strong (LREF mean sfc-500mb shear up to or even in excess of 50 knots), so if any deep updrafts are able to form, they will be in an environment that supports at least a limited damaging wind threat, though such a high shear/low CAPE environment lends question as to whether or not there could be too much shear for the little CAPE in place. This will all be ironed out more in the coming days. Flooding is of lower concern at this time given the preceding drought conditions and only around a 30% probability of exceeding an inch of rainfall (mainly across eastern Ohio) per the latest NBM. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... KEY MESSAGES: - Cooler weather returns next week - Periodic rain chances for the first half of the week ------------------------------------------------------------------- Notable upper level pattern discrepancy continues and increases into next week with some ensembles holding the trough back and closing it off into an upper low while others quickly progress it offshore as an open wave. The slower, deeper solution could result in rain chances remaining on Monday with low level cold advection and periodic shortwave passage while a quicker one allows high pressure and drier air to sneak in quicker. Think that we likely will keep some showers around Monday morning with lingering low level moisture and cold advection reinforcing steeper low level lapse rates, and the latest NBM offers 20-30% PoPs which seems reasonable at this juncture. High pressure does eventually build behind the departing low, though how long it stays around is uncertain as ensembles develop another surface low off to our northwest with additional rain chances returning as early as Tuesday. Given cascading differences among solutions even for this coming weekend, confidence beyond that timeframe is very low at this time. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... River valley fog this morning should quickly dissipate with the onset of heating/mixing. VFR is expected throughout the TAF period under high pressure. Winds out of the north-northwest increase to near 10 knots this afternoon with a few infrequent gusts to 15-20 mph, followed by light and variable winds overnight into early Friday. .OUTLOOK... Surface high pressure with height rises aloft favor VFR into Saturday before a series of shortwaves ahead of the next cold front bring increased rain and restriction chances. Breezy conditions are also possible on Sunday with strengthening southwesterly winds ahead of the cold front. Latest ensemble guidance suggests a >90% chance for gusts exceeding 30 mph areawide and even a 70% chance for peak gusts to exceed 40 mph in the PIT/AGC/HLG area (40-50% elsewhere across the area). && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Frost Advisory until 9 AM EDT this morning for PAZ007>009- 013>016-020>022-029-031-073>078. Freeze Watch from late tonight through Friday morning for PAZ007>009-013>016-020>022-029-031-073>078. OH...Frost Advisory until 9 AM EDT this morning for OHZ039>041-049- 050. Freeze Watch from late tonight through Friday morning for OHZ041. WV...Frost Advisory until 9 AM EDT this morning for WVZ001-002- 509>514. Freeze Watch from late tonight through Friday morning for WVZ001-509>514. && $$ SYNOPSIS...MLB NEAR TERM...MLB SHORT TERM...Cermak/MLB LONG TERM...MLB AVIATION...Cermak