


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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114 FXUS61 KPBZ 181757 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 157 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 TONIGHT/... 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 THROUGH 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 /18Z SATURDAY THROUGH THURSDAY/... Confidence remains high for VFR conditions through the TAF period as strengthening southwest flow promotes warm advection. High resolution model guidance suggest minimal low-level cumulus development this afternoon given prevailing subsidence. Warm air advection aloft early Sunday morning (pre-12z) may limit surface wind gusts, which would increase the potential for LLWS (35-45kts) due to a strong vertical wind profile immediately above the surface. However, confidence in this decoupling occurring is too low to warrant inclusion of LLWS in TAFs in this cycle. It will continue to be considered in future cycles as additional guidance becomes available. .OUTLOOK... A low pressure system will move west to east across the region between 15Z and 23Z Sunday, bringing rain showers and isolated thunderstorms. Some of the heavier showers and storms could be capable of producing wind gusts exceeding 50 kts given the strong flow aloft. Even outside of convection, downward mixing will result in gusts ranging from 30 to 40 kts, with peak non- convective gusts potentially reaching as high as 45kts in some of our typically windier locations. Scattered to isolated showers and gusty westerly winds are expected in the wake of the cold front late Sunday. 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, however 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 NEAR TERM...Cermak SHORT TERM...Cermak/MLB LONG TERM...AK AVIATION...Cermak