327 FXUS61 KPBZ 210856 AFDPBZArea Forecast Discussion National Weather Service Pittsburgh PA 456 AM EDT Sun Sep 21 2025
.SYNOPSIS... Above normal temperatures will continue while shower and storm chances increase later today and into next week.
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.NEAR TERM /UNTIL 6 PM THIS EVENING/... KEY MESSAGES:
- Largely dry conditions today - Continued above normal temperatures ---------------------------------------------------------------
Patchy fog is possible where rain occurred yesterday and sees partial clearing, but otherwise, most spots will see at least scattered cloud coverage. Low temperatures will bottom out 5 to 10 degrees above average with the increased cloud coverage due to a crossing shortwave. Latest CAMs show very limited convective activity through the afternoon, and model soundings show warmer air in the lower levels keeping a lid on things.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... KEY MESSAGES:
- Rain chances increase tonight with a warm front ----------------------------------------------------------------
Tonight the area will see increasing rain chances as a warm front crosses the region, particularly over eastern Ohio counties where latest ensemble guidance shows up to 50% PoPs.
Coverage and organization this evening with better deep layer shear as a broad south/southwest 20-25 knot low level jet develops beneath increasing veering flow up to 700 mb. HREF joint probabilities for >1000 J/kg SBCAPE and 25 knots of 0-6km bulk shear reaches around 25-30% which could point toward a low end wind threat, though latest CAMs suggest arrival time around sunset in our eastern Ohio counties which would not necessarily be the most ideal time, and latest CSU-MLP guidance and CIPS analog guidance do not show a wind threat for today.
SPC has maintained a Marginal Risk (1/5) for damaging wind for eastern Ohio, but a lower severe threat is a plausible solution in our area if arrival time does prove to be after sunset.
Additional shortwaves will support a continued chance of showers overnight. Warm advection with elevated southerly flow likely means lows won`t dip out out of the 60s across the area save north of I-80. On Monday, the Day 2 Marginal was expanded east almost to the ridges as there should be better shear to organize convection. Still, the threat will primarily be damaging winds. This is supported by latest machine learning guidance.
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.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... KEY MESSAGES:
- Measurable rain expected in the period - Near average temperatures expected late week ------------------------------------------------------------------
Ridging over the northeast CONUS will weaken as an upper trough drops in out of the north. This will result in increased west southwesterly flow, elevated dew points, and enhanced vertical wind shear that will increase chances for showers and thunderstorms that will persist through midweek.
Through early Tuesday morning, ensemble guidance indicates a probability exceeding 60% for at least a quarter inch of precipitation for areas north of Pittsburgh and into eastern Ohio. The probability of one inch of rain is considered low over the 24 hour time period (less than 15%). As we progress into the mid to late week time period, the potential for additional rainfall and near- normal temperatures is noted due to an upper- level low over the southeast CONUS. Overnight low temperatures may remain 5 degrees above average with lingering low-level moisture and increased cloud coverage.
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.AVIATION /09Z SUNDAY THROUGH THURSDAY/... Dry weather is expected for the remainder of the overnight and most of the day, though an isolated stray shower may still be possible. Winds will remain light and variable overnight. Fog is possible, but low probability, at MGW near sunrise.
Additional convection is expected later today with a crossing shortwave, but latest CAM runs have pushed this activity later than previously expected. Accordingly, have dropped PROB30 groups from TAF mention for all put ZZV, which could see thunder after 00z Monday, and PIT, which may see remnant light showers closer to dawn Monday.
.OUTLOOK.... A series of shortwaves will provide varying rain chances through the middle of the week. While VFR is likely to be the predominant flight category through this timeframe, periods of heavier rain and/or patchy morning stratocu may result in MVFR restrictions.
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.PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None.
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SYNOPSIS...88 NEAR TERM...88 SHORT TERM...88 LONG TERM...88 AVIATION...Rackley
NWS PBZ Office Area Forecast Discussion