916
FXUS61 KPBZ 151812
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
212 PM EDT THU OCT 15 2026
WHAT HAS CHANGED
RAIN SHOWER CHANCES HAVE DECREASED TODAY. ADDED A MENTION OF
THUNDER ON FRIDAY WITH A STRONG COLD FRONT. A PORTION OF THE
AREA GENERALLY EAST OF I-79 HAS BEEN INCLUDED IN A MARGINAL RISK
FOR SEVERE STORMS WITH DAMAGING WINDS ON FRIDAY.
KEY MESSAGES
1) SHOWERS, POSSIBLE THUNDERSTORMS, AND GUSTY WIND TONIGHT AND
FRI.
2) COLDER BEHIND THE FRONT, WITH FROST AND FREEZE CONDITIONS
SAT NIGHT. FROST MAY BE POSSIBLE AGAIN SUN NIGHT.
3) DRY AND WARMER NEXT WEEK, BUT THE FORECAST HAS VERY LOW
PREDICTABILITY AT THIS TIME.
DISCUSSION
KEY MESSAGE 1...
STORMS FORMING IN THE MIDWEST TODAY HAVE A LOW PROBABILITY OF
MAINTAINING STRENGTH TONIGHT AS A LOW-LEVEL JET AND NWD-
ADVANCING WARM FRONT HELP MAINTAIN ONLY MODEST STABILIZATION IN
A MOISTENING BOUNDARY LAYER. IF STORMS ARE MAINTAINED, IT WILL
BE POSSIBLE TO SEE A STRONGER GUST OR TWO, BUT THE LIKELIHOOD OF
IMPACTFUL WEATHER TONIGHT REMAINS LOW.
OF GREATER CONCERN IS POTENTIAL FOR STRONGER LOW-TOPPED
CONVECTIVE DEVELOPMENT ON FRI, WHERE BUOYANCY CONCENTRATED IN
THE LOWER LEVELS OF THE ATMOSPHERE WILL OVERLAP FAVORABLY WITH
CONVERGENCE WITHIN A PRE-FRONTAL TROUGH WITHIN A MODERATELY
SHEARED ENVIRONMENT.
THERE REMAINS TIMING/POSITIONAL UNCERTAINTY IN THE PLACEMENT OF
THE PRE-FRONTAL TROUGH CONVERGENCE ZONE, WITH SOME GUIDANCE
SUGGESTING A SLOWER PROGRESSION. IF THIS SLOWER PROGRESSION
MATERIALIZES, THERE WILL BE BETTER POTENTIAL FOR DESTABILIZATION
AS ENHANCED ASCENT OVERSPREADS THE REGION WITHIN A STRONG MID-
LEVEL JET STREAK.
BETTER POTENTIAL FOR SEVERE WEATHER EXISTS TO THE EAST OF THE
UPPER OHIO VALLEY, BUT AT THIS TIME, WE CANNOT RULE OUT THE
POTENTIAL FOR THE WRN POSITION OF THE INITIATING BOUNDARY. IF IT
BECOMES CLEAR THAT THE BOUNDARY IS FAVORING EARLIER PASSAGE, THE
SEVERE WEATHER THREAT LOCALLY WILL BE MINIMIZED.
KEY MESSAGE 2...
COLD ADVECTION IN THE WAKE OF A STRONG COLD-FRONTAL PASSAGE
WILL SUPPORT RENEWAL OF LAKE-ENHANCED SHOWERS FRI NIGHT WITHIN A
PLUME OF STEEPER LOW-LEVEL LAPSE RATES. TEMPERATURE IS NOT
EXPECTED TO COOL SUFFICIENTLY FOR NOTABLE SNOW, ALTHOUGH LOW
(<10%) CHANCES FOR SNOW EXIST AT THE HIGHEST ELEVATIONS OF THE
WV RIDGES THRU THE WEEKEND.
ELEVATED WIND AND CLOUD COVER FRI NIGHT ARE LIKELY TO PRECLUDE
FROST/FREEZE CONCERNS, BUT CONDITIONS WILL BECOME MORE FAVORABLE
SAT NIGHT AS WIND SLACKENS AND CLOUD COVER DISSIPATES.
CLUSTER ANALYSIS SUGGESTS TWO POTENTIAL H5 PATTERNS THAT WILL
GOVERN THE SAT/SUN EVOLUTION:
1) THE SCENARIO THAT IS MORE LIKELY SUGGESTS THE H5 TROUGH
ADVANCING BODILY EWD, WITH COLD AIR BUILDING IN SAT NIGHT
LEADING TO WIDESPREAD TEMPERATURE IN THE 30-35F RANGE AND
POTENTIAL FROST/FREEZE CONDITIONS.
2) A SECOND SCENARIO FEATURES LOW PRESSURE CUTTING OFF FROM THE
MAIN TROUGH, LEADING TO A QUICKER DEPARTURE, LESS COLD AIR
INTRUSION, AND COOLER TEMPERATURE/FROST POTENTIAL FAVORING
MAINLY THE RIDGES/NORTHEASTERN MOST ZONES.
ENSEMBLE SENSITIVITY ANALYSIS (ESA) SUGGESTS THAT THE SECOND
SCENARIO IS DRIVEN BY THE STRENGTH OF A H5 RIDGE CURRENTLY
BUILDING IN THE WRN CONUS, AND THE TIMING OF PHASING OF TS SIMON
INTO THE BROADER FLOW. IF THE RIDGE IS STRONGER AND TS SIMON
SLOWER TO PHASE, IT FAVORS A CUTOFF LOW DEVELOPMENT AND WARMER
OUTCOME AS DISCUSSED IN OUTCOME 2 ABOVE.
MONITOR THE FORECAST FOR FROST/FREEZE POTENTIAL. GREATEST
CONFIDENCE IN IMPACTFUL TEMPERATURE WILL BE THE NORTHEASTERN
ZONES, AS TEMPS OF 30-35 ARE MOST LIKELY THERE IN EITHER
OUTCOME ABOVE.
KEY MESSAGE 3...
IN THE WAKE OF THE TROUGH, QUITE A BIT OF UNCERTAINTY GROWS WITH
THE MEDIUM-RANGE PATTERN NEXT WEEK. MUCH OF THE GUIDANCE FAVORS
A H5 RIDGE BUILDING ACROSS THE MIDWEST, SUGGESTING INCREASING
WARMTH FOR THE UPPER OHIO VALLEY. HOWEVER, OTHER GUIDANCE
SUGGESTS TROUGHING COULD DEVELOP, WHICH WOULD FAVOR COOLER
TEMPERATURE.
THE DEGREE OF RIDGING OR TROUGHING IN THE EAST APPEARS HIGHLY
CORRELATED TO THE POSITION OF A WRN-CONUS TROUGH/POTENTIAL
CUTOFF LOW AROUND MON/TUE TIMEFRAME. GIVEN THIS WIDE VARIABILITY
AND DEPENDENCE ON ATMOSPHERIC FLOW FEATURES THAT DO NOT YET
EXIST, THE FORECAST NEXT WEEK HAS VERY LOW PREDICTABILITY, AND
SHOULD BE CONSUMED WITH THAT AWARENESS.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
BVI, FKL, AND DUJ ARE THE ONLY TERMINALS THAT REMAIN VFR. THEY
WILL GRADUALLY LOWER TO MVFR CIGS AS THE WARM FRONT CONTINUES
TO LIFT NORTHWARD.
FURTHER DETERIORATION TO LOW MVFR, AND EVENTUALLY IFR, IS
EXPECTED THIS EVENING AND TONIGHT AS THE FRONT CROSSES, AND
SHOWERS OVERSPREAD THE REGION. THERE COULD BE ISOLATED
THUNDERSTORMS AS WELL WITH ELEVATED INSTABILITY AND A CROSSING
LOW LEVEL JET. THIS JET SHOULD ALSO RESULT IN A LLWS POTENTIAL
FROM LATE EVENING THROUGH THE OVERNIGHT HOURS.
OVERNIGHT, WE WILL ALSO SEE THE WIND VEER FROM EAST TO SOUTH AS
CONDITIONS REMAIN RELATIVELY BREEZY. BY TOMORROW MORNING, AREAS
AROUND PIT AND SOUTH, ARE FORECAST TO BRIEFLY SCATTER OUT BY
TOMORROW MORNING. DURING THE DAY, SHOWERS AND POSSIBLE
THUNDERSTORMS AHEAD OF A STRONG FRONT WILL BRING LOW MVFR AND
IFR CIGS TO AREAS THAT WERE ABLE TO SCATTER OUT. WIND WILL
FRESHEN UP AS IT VEERS TO THE WEST. GUSTS UP TO 30-40KTS ARE
LIKELY WITH HIGHER GUSTS UP TO 45-50KTS POSSIBLE ACROSS THE
HIGHER TERRAIN AIRPORTS.
OUTLOOK...
SHOWERS WILL CONTINUE FRIDAY NIGHT UNDER SUBSEQUENT UPPER
TROUGHING. BUILDING HIGH PRESSURE WILL RETURN DRY WEATHER
SATURDAY INTO NEXT WEEK. WIND WILL ALSO DIMINISH ON SATURDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...KRAMAR/WM
AVIATION...LUPO
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