057 FXUS61 KPBZ 202114 AAA AFDPBZArea Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 514 PM EDT Sat Sep 20 2025
.SYNOPSIS... Above normal temperatures will continue through the weekend. A few showers and storms will continue south of Pittsburgh this evening, but the better chance for more widespread precipitation will arrive later on Monday and continue through mid-week.
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.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... KEY MESSAGES:
- Scattered showers/storms this afternoon south of Pittsburgh - Continued above normal temperatures ---------------------------------------------------------------
515 PM Update... Updated POPs according to the latest radar trends and mesoanalysis. Had reports of 1/2 inch hail with several of the stronger storms this afternoon. A couple of storms could have had potentially larger hail. Locally heavy rain was also occuring, especially across far SW PA and Nrn WV, though dry antecedent conditions were in place. ML CAPE has remained from 1000-1500 j/kg, but has shifted eastward into nrn WV. Current indications are the convection should begin to diminish around sunset as instability slowly wanes.
304 PM Update... Increased POPs for the I 70 corridor, where convergence in the vicinity of a surface boundary has resulted in showers and thunderstorms developing. Radar indicated hail is possible in some of these storms as they pulse up in strength. With dry air aloft in place, some gusty wind is also possible. Added these attributes to the grids as well. The latest mesoanalysis shows 1000-1500 j/kg ML CAPE in this region as well, with increased moisture in the lower levels. DCAPE values are around 500-600 j/kg, especially across OH, where more mid level dry air is observed.
Previous discussion... Dry conditions are expected for most through today with surface ridging extending south from an area of high pressure centered over Ontario. Some mid to upper level clouds will stream through on the periphery of a central CONUS mid-level trough with a light easterly wind.
The exception to the dry conditions will be along and south of I-70 and perhaps the WV Panhandle where modest convergence along a stalled frontal boundary and orographic ascent may be enough to spark off a few showers/storms this afternoon. HREF prob of SBCAPE >1000 J/kg sneaks up to around 60-70% with weak cloud layer mean wind which points toward poor convective organization. With higher PWAT values around 1.1-1.2" and modest CAPE, probability for >0.5" of rain is actually not zero across northern West Virginia reaching as high as 30-40%, though rainfall will be localized.
Could see a few showers linger overnight as weak shortwave energy traverses the area and the stationary boundary wiggles around, but coverage should generally wane after sunset. Overnight lows will remain mild with elevated southeasterly flow and steady to gradually increasing dew points overnight. Fog development should be limited given the elevated wind, but sheltered areas or those that see some rain today could have some after midnight.
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.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... KEY MESSAGES:
- Additional showers/storms possible later Sunday in eastern Ohio - Temperatures remain above normal ----------------------------------------------------------------
Saturday`s stalled boundary is progged to lift north with increasing southerly surface flow and given an extra kick by the aforementioned shortwave energy. This will allow for an increase in temperatures and dew points with a summer-like feel with mid to upper 80s for highs and low to mid 60s for dew points. Meanwhile, modest mid-level height falls will occur on Sunday as shortwave energy rotates through the Great Lakes regions. This is expected to initiate initially disorganized scattered showers and thunderstorms across the Ohio Valley in the early to mid afternoon hours that will slide north and east into the evening and eventually into our eastern Ohio counties closer to sunset. Coverage and organization should increase a bit headed into the evening hours 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 prob for >1000 J/kg SBCAPE and 20 knots of deep layer shear reaches 40-50% which could point toward a low end wind threat, though latest CAMs suggest arrival time around sunset in our eastern Ohio Counties. SPC day 2 outlook has encompassed those counties in a Marginal Risk (1/5) for damaging wind, but a lower severe threat is a plausible solution in our area if arrival time does prove to be after sunset.
Additional shortwave movement 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.
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.LONG TERM /MONDAY THROUGH SATURDAY/... KEY MESSAGES:
- Measurable rain expected within the long term period - Near average temperatures expected late week ------------------------------------------------------------------
Confidence is high that a ridge axis over the Northeast will dissipate as a trough ejects into the Great Lakes region. This will result in an increase in southwest flow, leading to elevated dew points and enhanced vertical wind shear and increase our chances for showers and thunderstorms during this time period. As for timing, precipitation chances will increase across the Ohio River Valley beginning early Monday morning and persisting into Tuesday.
Through early Tuesday morning, global 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 a lingering upper-level low centered to our southwest. Overnight low temperatures may remain 5 degrees above average with lingering low-level moisture and increase coverage.
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.AVIATION /21Z SATURDAY THROUGH THURSDAY/... VFR conditions are likely to continue through Saturday night as surface ridging extends south from high pressure located across Ontario. Weak surface convergence along a stalled frontal boundary south of PIT, along with orographic ascent, should be enough to yield a few showers/storms this afternoon with highest probability across northern WV. Probability for impacts to MGW are low and confidence has only warranted a PROB30 mention. Elsewhere, scattered mid to upper level clouds will stream overhead and wind remains light out of the east.
MVFR probability increases along and east of the ridges overnight Saturday night with persistent easterly flow advecting Atlantic moisture inland in the form of low stratus. DUJ/LBE see 40-60% probability of ceilings
NWS PBZ Office Area Forecast Discussion