035 FXUS61 KPBZ 062251 AFDPBZArea Forecast Discussion National Weather Service Pittsburgh PA 651 PM EDT Sat Sep 6 2025
.SYNOPSIS... A prolong period of dry weather is expected to start tonight. Cool temperatures through Sunday will be followed by a slow warming trend during the work week.
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.NEAR TERM /THROUGH SUNDAY/... KEY MESSAGES:
- Drier weather tonight into Sunday, save for a few showers north of I-80 Sunday - Temperatures will continue to be 10 degrees below normal on Sunday ---------------------------------------------------------------
Clouds will continue erode from west to east over the next 6 hours with advancing dry air noted on low-level water vapor satellite.
Patchy fog may develop within the river valleys between 3am and 6am Sunday morning with clearing clouds and light winds.
Sunday will feature dry weather for most, with low- level ridging taking control over the Upper Ohio Valley. Model soundings indicate enough modest, shallow instability for diurnal cumulus development. With 850 temps of 3-4C advecting over Lake Erie water temps of 22C or so, a few lake-effect rain showers will be possible north of I-80 during the day. Temperatures will be fairly similar to today, as increased sunshine is offset by the cooler 850mb temperatures.
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.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... KEY MESSAGES:
- Drier and warmer Monday into Tuesday - Patchy valley fog each morning --------------------------------------------------------------
There is high confidence in height rises Sunday night into Monday as the main eastern trough axis weakens in amplitude and moves off to the east, replaced by a central conus ridge axis riding up the Ohio Valley. This will clear skies overnight Monday allowing efficient radiative cooling to take lows around 15 degrees below average with patchy valley fog. Monday, mixing will allow warmer (but still below average) afternoon temperatures Monday with only patchy afternoon cumulus with dry conditions.
Monday night into Tuesday will bring much of the same with cool lows and valley fog, followed by another day of heating. Correspondingly, temperatures are forecast to climb a couple degrees compared to the day prior, but still remain slightly below average. High clouds may increase through Tuesday as upper moisture blows off from a coastal southeast low.
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.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... KEY MESSAGES:
- Seasonable temperatures and dry late-week - Forecast uncertainty grows next weekend ------------------------------------------------------------------
There appears to be a continued consensus that upper shortwave troughing drops over the area through the Wednesday to Friday period, slowing the warming trend and keeping temperatures near average. Despite the upper veering flow, near-surface high pressure and subsidence is forecast to prevail, keeping temperatures near climatological normal and much of the area dry.
Ensemble uncertainty begins to snowball on Friday through next weekend as ensembles struggle with 1) just how long to keep the weak eastern troughing around 2) the amplitude and eastward extent of a central CONUS ridge, and 3) the lower-probability event of reinforced troughing pattern developing next weekend. The range of all solutions would have temperatures anywhere from around 10 degrees above average to 10 degrees below average. On the whole, ensemble means hold temperatures steady, but trends are likely to fall on either side as pattern resolution continues. In all scenarios except the low- probability of a strong upper trough reinforcement, however, rainfall will remain limited to none.
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.AVIATION /00Z SUNDAY THROUGH THURSDAY/... High clouds will continue to erode from west to east through 03Z; VFR conditions will generally prevail through the TAF period minus some patchy fog between 06Z to 12Z.
MGW, LBE, and DUJ have the best shot at a period of MVFR/IFR visibility according to HREF probabilities, and have included mention in those TAFs.
Any fog will lift by 13Z Sunday, with VFR for the balance of the day. Afternoon cumulus and some northwest wind gusts to around 15 knots will be possible after 15Z. FKL/DUJ may experience a stray shower between 15Z to 22Z due to lake enhancement, but vis and cig impacts will remain low.
.OUTLOOK.... Isolated sites may experience valley fog for brief periods during the early morning hours in the long term. Otherwise, mostly VFR conditions.
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.PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None.
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SYNOPSIS...Hefferan NEAR TERM...Hefferan SHORT TERM...Milcarek LONG TERM...Milcarek AVIATION...Hefferan/CL
NWS PBZ Office Area Forecast Discussion