796
FXUS61 KPBZ 210454
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1254 AM EDT TUE OCT 21 2025
SYNOPSIS
SHOWER CHANCES INCREASE LATE MORNING WITH A PASSING WARM FRONT.
ADDITIONAL SHOWER AND ISOLATED THUNDERSTORMS ARE EXPECTED THIS
EVENING WITH A PASSING SHORTWAVE.
NEAR TERM /THROUGH TODAY/
KEY MESSAGES:
- DRY WEATHER THROUGH LATE MORNING
- PASSING WARM FRONT WILL BRING A LINE OF LIGHT SHOWERS
- ADDITIONAL SHOWERS/THUNDERSTORMS EXPECTED LATE THIS EVENING
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QUIET AND DRY WEATHER ARE EXPECTED THROUGH SUNRISE UNDER THE
INFLUENCE OF HIGH PRESSURE. MID AND UPPER-LEVEL CLOUDS WILL
LIKELY EXPAND INTO EASTERN OHIO JUST BEFORE DAWN IN ADVANCE OF
AN APPROACHING DISTURBANCE.
THE PROBABILITY OF MEASURABLE RAINFALL INCREASE BETWEEN 7AM AND
11AM AS A WARM FRONT MOVES ACROSS OHIO AND WESTERN
PENNSYLVANIA. GIVEN ADEQUATE SHEAR TO KEEP SHOWERS PROGRESSIVE
AND LIMITED MOISTURE DEPTH, RAINFALL TOTALS WITH THIS INITIAL
ROUND OF PRECIPITATION ARE EXPECTED TO REMAIN UNDER A QUARTER
INCH.
BETWEEN 4PM AND 7PM, ADDITIONAL SHOWERS AND ISOLATED
THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS OHIO AND MOVE
EASTWARD AS A 40KT LOW-LEVEL JET AT 850MB ADVANCES INTO CENTRAL
OHIO. CLEARING IN THE WAKE OF THE WARM FRONT WILL LIKELY ENHANCE
SHALLOW INSTABILITY (150-350J/KG) ACROSS EASTERN OHIO AND MAY
BE SUFFICIENT TO SUPPORT LIGHTNING DEVELOPMENT AND GUSTY
(40-45MPH) CONDITIONS WITHIN CONVECTION THAT COULD LAST INTO
THE OVERNIGHT TIME PERIOD.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- ISOLATED SHOWERS AND STORMS TONIGHT
- PROLONGED PERIOD OF BELOW NORMAL TEMPERATURE AND LAKE ENHANCED
SHOWER ACTIVITY
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SHOWERS AND ISOLATED THUNDERSTORMS WILL LIKELY PERSIST TONIGHT
AS A SHORTWAVE MOVES THROUGH THE REGION. LIGHTNING AND GUSTY
WINDS ASSOCIATED WITH CONVECTION WILL BE THE PRIMARY CONCERN
THROUGH 1AM WEDNESDAY, AFTER WHICH PRECIPITATION WILL BECOME
MORE CONCENTRATED NORTH OF PITTSBURGH DUE TO DEVELOPING LAKE-
EFFECT PROCESSES.
COLD ADVECTION ASSOCIATED WITH A BROAD LOW OVER THE GREAT LAKES
WILL LIKELY MAINTAIN BREEZY CONDITIONS ON WEDNESDAY. UNDER
MOSTLY CLOUDY SKIES, TEMPERATURES ARE EXPECTED TO RANGE FROM THE
UPPER-30S TO MID-40S EARLY IN THE MORNING, RISING TO THE LOW TO
MID-50S BY THE AFTERNOON.
DRY SLOTTING AROUND THE UPPER LOW FAVORS DISSIPATING RAIN
CHANCES FOR LOCATIONS SOUTH OF I-80 THROUGH THURSDAY MORNING.
NORTH OF I-80, LAKE EFFECT RAIN SHOWERS WILL LIKELY CONTINUE,
CAUSED BY LARGE VARIATION IN LAKE TEMPERATURE (CURRENTLY AROUND
NEAR 18 DEGREES C) TO 850MB TEMP (NEAR 0 DEGREES C). SOME
SUBTLE VARIATION IN 850MB FLOW DIRECTION EXISTS, BUT ENSEMBLE
MEANS FAVOR A MOSTLY WSW 850MB FLOW THAT WOULD KEEP A MAJORITY
OF SHOWERS TO THE NORTHERN TIER OF FORECAST COUNTIES.
THERE MAY BE ONE LAST SHORTWAVE SURGE SOUTHEAST THURSDAY AS THE
UPPER TROUGH BEGINS EXITING TOWARD NEW ENGLAND THAT MAY OFFER
LOW PROBABILITY LIGHT RAIN SHOWERS TO MOST LOCATIONS THROUGH THE
DAY. OTHERWISE, HEIGHT RISES AND BUILDING SURFACE HIGH PRESSURE
BY THURSDAY EVENING WILL END PRECIPITATION CHANCES FOR ALL
LOCATIONS.
LONG TERM /FRIDAY THROUGH MONDAY/
KEY MESSAGES:
- DRY WEATHER AND TEMPERATURE MODERATION FAVORED FRIDAY/SATURDAY
- WIDESPREAD PRECIPITATION CHANCES RETURN SUNDAY
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ENSEMBLE MODEL GUIDANCE FAVORS BROAD HEIGHT RISES WITHIN
WESTERLY FLOW AS SURFACE HIGH PRESSURE SLOWLY CROSSES THE
REGION. TEMPERATURE WILL MODERATE TOWARD SEASONAL AVERAGES WHILE
PRECIPITATION SHOULD REMAIN SOUTHEAST OF THE REGION.
VARIABILITY GROWS THEREAFTER AS MODELS ARE SCATTERED IN
RESOLVING THE PROGRESSION OF A CUT-OFF LOW ATTEMPTING TO LIFT
OUT OF THE TX PANHANDLE AND ITS INTERACTION WITH A NEW ENGLAND
TROUGH OF VARYING DEPTH. THE MOST THAT CAN BE SAID IS THAT THE
FAVORED SCENARIOS WOULD BRING THE NEXT ROUND OF RAIN SUNDAY INTO
EARLY NEXT WEEK WITH NEAR NORMAL TEMPERATURE.
AVIATION /04Z TUESDAY THROUGH SATURDAY/
A MOSTLY CLEAR SKY IS FORECAST FOR MUCH OF THE NIGHT AS AN UPPER
RIDGE CROSSES THE AREA, ALTHOUGH SOME MID AND UPPER CLOUD MAY
BEGIN TO SHOW UP TOWARDS SUNRISE AHEAD OF THE NEXT SHORTWAVE
TROUGH. WIND HAS MOSTLY DIMINISHED THIS EVENING, WITH LIGHT
SOUTHERLY FLOW EXPECTED OVERNIGHT. A SHIFT BACK TO SOUTHWESTERLY
IS EXPECTED AFTER 12Z TUESDAY AS BREEZY CONDITIONS RETURN, WITH
SUSTAINED SPEEDS INCREASING TO AROUND 10-15 KNOTS AND GUSTING
TO 20-25 KNOTS THROUGHOUT THE DAY. TWO ROUNDS OF SCATTERED
SHOWERS WILL MOVE ACROSS THE AREA FROM WEST TO EAST ON TUESDAY,
THE FIRST IN THE 10Z-15Z TIMEFRAME AND THE SECOND LATER IN THE
DAY (AFTER 18Z). LOCAL DIPS TO MVFR CEILINGS/VISIBILITIES WILL
BE POSSIBLE IN HEAVIER INSTANCES OF RAIN, BUT OTHERWISE VFR
SHOULD CONTINUE TO PREVAIL.
OUTLOOK
RAIN CHANCES AND ASSOCIATED RESTRICTION POTENTIAL CONTINUES
WEDNESDAY AND THURSDAY MAINLY NORTH OF PITTSBURGH AS A SERIES OF
WEAK SHORTWAVE TROUGHS CROSS THE GREAT LAKES. DAYTIME WINDS MAY
CONTINUE TO BE BREEZY THROUGH THAT TIME BEFORE SETTLING AS WE
HEAD INTO THE UPCOMING WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...HEFFERAN
SHORT TERM...FRAZIER/HEFFERAN
LONG TERM...FRAZIER
AVIATION...CERMAK/CL
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