


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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643 FXUS61 KPBZ 182321 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 721 PM EDT Sat Oct 18 2025 .SYNOPSIS... Unseasonably warm weather continues tonight. A strong cold front will bring showers, thunderstorms, and gusty winds on Sunday. More seasonable temperatures return next week with periodic rain chances and breezy conditions. && .NEAR TERM /THROUGH SUNDAY/... KEY MESSAGES: - Unseasonably warm tonight - An isolated shower or two possible west of I-77 before sunrise --------------------------------------------------------------- Strengthening deep-layer southwesterly flow will begin to transport low-level moisture back into the area, with dewpoints climbing into the 50s by tonight. This, combined with increasing cloud cover and a stiff southerly gradient flow, will result in overnight lows remaining well above seasonal levels; in fact they may be close to our normal *high* temperature this time of year. Can`t entirely rule out a shower sneaking into eastern Ohio counties (mainly west of I-77) towards sunrise ahead of a strengthening front approaching our area from the west. && .SHORT TERM /SUNDAY NIGHT/... KEY MESSAGES: - Cold front passage Sunday offers high chance of rain and windy conditions - A possible convective line on Sunday afternoon could produce damaging wind gusts ---------------------------------------------------------------- As a central CONUS trough deepens and progresses east, associated surface cyclogenesis occurs across the Plains and rapidly lifts northeast toward the Great Lakes riding along a pre-existing weak boundary. The low will deepen rapidly and strengthen the boundary, pulling it through here as a cold front on Sunday afternoon. This system will pack quite the dynamic punch and bring a two-fold threat of severe weather and strong wind gusts with it. The pressure gradient tightens between the aforementioned surface low and and departing high pressure then centered offshore. Deep layer flow through the entire column follows suit as 925 mb flow jumps to 30+ knots and 850 mb flow to 40+ knots. Tapping into the enhanced low-level flow and working in tandem with the tight pressure gradient, wind will be quite gusty on Sunday. The latest NBM continues to suggest a very high probability (>90%) for frequent wind gusts exceeding 30 mph across our entire area. Probability for occasional gusts over 40 mph continues its incremental increase now up to 50-80%. Above that, probabilities quickly drop off, with only a 10-20% chance of >50 mph, and thoughts are that this is likely tied to potential gusts within a convective line of showers/storms that should form along the cold front. We`ve now gotten this event within range of most all of the CAMs to glean a better idea of how that narrow convective line may evolve. As has been the case for the past couple days, limited instability is still the main hindrance with thick cloud coverage in the morning and some pre-frontal rain depicted by most of the CAMs which acts detrimentally for destabilization. Very few are all that excited about more than 100-300 J/kg of MLCAPE. Despite this, strong forcing both along the front and synoptically with diffluent flow and shortwave-aided ascent should be sufficient in tandem with the limited CAPE to overcome the subpar thermodynamics. Deep layer shear still remains around 50-60 knots with low level shear in the 0-3 km layer around 30-35 knots. Given this, think it`s plausible that we see a narrow, low topped convective line along the cold front that will bring primarily a damaging wind threat. With such strong background flow, it won`t take much convective enhancement to get to 60 mph gusts. Low level shear vectors are southwesterly, so can`t completely rule out an embedded QLCS tornado threat, but only if any segments along the convective line are able to orient northwesterly to southeasterly (normal to the shear). Of note, there may not be much lightning associated with convection as thermodynamic profiles are saturated through ~500 mb and modeled equilibrium levels hover generally below the -10C level, which is unfavorable for ice production and charge separation. With the passage of the cold front Sunday afternoon/evening, winds shift to westerly and the severe threat ends. Breezy conditions are expected to continue through Sunday night. Rain chances also continue as low level cold advection reinforces fumes of instability and we don`t work dry air in immediately behind the boundary. && .LONG TERM /MONDAY THROUGH SATURDAY/... KEY MESSAGES: - Cooler weather returns next week - Periodic rain chances continue through the week ------------------------------------------------------------------- Lingering showers should taper across the region before sunrise on Monday as the upper trough swings out of the area and heights begin to rise. A northwesterly upslope flow regime could help drizzle linger into the afternoon across our ridges. Overall though, expect dry air to win out and skies are expected to clear throughout the day and evening from west to east. High temperatures are expected to be stunted across the region Monday and return to near normal values after consecutive days well above. Another upper trough swings across the Great Lakes and impinges on the region by Tuesday. Clustered ensembles still indicate timing and positional uncertainty with this wave but seem to favor a possible slower eastward movement as an upper low tries to close off in the base of the trough. At the SFC another low pressure system is expected to occlude in the northern Great Lakes and push a developing triple point low and cold front across the region. At this time the highest rain chances remain north, closest to the low but lower end rain chances extend southward across the remainder of the region along the front. Temperatures look to drop again in the wake of this low mid- week with below normal temperatures for this time of year and continued low-end rain chances as shortwaves round the base of the parent trough. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... Confidence remains high in VFR conditions area-wide at least through daybreak with high pressure being shunted to the east. Encroaching clouds are expected to thicken and lower, however, with the approach of the next system. An increasing pressure gradient overnight over a decoupled surface is expected to accelerate winds some aloft, though gusts are not expected to approach LLWS tolerance. Come daybreak tomorrow, mixing is expected to ensue, allowing momentum transfer to the surface with wind gusts through much of the late morning and early afternoon. Confidence in any LLWS wains, as mixing most likely, but will continue to monitor for future TAF cycles. The low pressure and rainfall are not expected to encroach the area from the west until 14Z at ZZV (along with the first non- zero chance of MVFR/IFR). A rapid cig fall is expected in heavier showers and especially along a cold front that will pass most ports in the afternoon hours. A couple hundred joules of CAPE may also be enough to produce isolated bouts of lightning within the line. Low level moisture and rapid surface cooling may also result in some vis reductions to MVFR/IFR at times. It is possible that some winds in the strongest, linearly oriented parts of the cold front in a shower/storm may experience a brief wind gust of up to 50kts, though most will not. This is most likely in western PA and northern WV. Elsewhere, most of the afternoon will be gusty with mixing into a LLJ. The most likely maximum values will lie between 30kts and 40kts, but localized higher gusts could not be ruled out. The gustiest winds are most likely to depart after 00Z for ports as the surface low sits overhead, but some winds may briefly pick up again overnight to 20kt to 30kt as the pressure gradient again intensifies on the backside of the low. Again, most of the is expected to mix in adiabatic profiles, but even if there is some surface decoupling, LLWS is possible. Showers and vis restrictions may also linger in nocturnal cold advection. .OUTLOOK... The likelihood of MVFR to IFR cigs increases Sunday night into early Monday with cold advection within the boundary layer. High pressure will likely restore VFR conditions after sunrise Monday, save perhaps FKL and DUJ with lake influence. Winds may continue to be breezy through at least mid week as probabilities for gusts exceeding 25 kts remain high (>60% chance) each afternoon through Wednesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Cermak/MLB NEAR TERM...Cermak/MLB SHORT TERM...Cermak/MLB LONG TERM...MLB/AK AVIATION...Milcarek