438
FXUS61 KPBZ 201141
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
641 AM EST SAT DEC 20 2025
SYNOPSIS
DRY WEATHER FAVORED THROUGH THE WEEKEND WHILE TEMPERATURES
OSCILLATE BETWEEN A RISE ON SATURDAY AND FALL ON SUNDAY.
THE NEXT WEATHER SYSTEM FEATURING A MIX OF RAIN AND SNOW WILL
CROSS MONDAY NIGHT INTO TUESDAY. THEREAFTER, PERIODIC
PRECIPITATION CHANCES MAY CONTINUE WHILE AREA TEMPERATURE TRENDS
ABOVE THE SEASONAL AVERAGES.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- COOL START BUT SEASONABLE FINISH FOR TEMPERATURE TODAY
- SUNSHINE MAY BE MORE LIMITED NORTH OF PITTSBURGH
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WEAK SHORTWAVE MOVEMENT NORTH OF THE REGION BUT WITHIN BROAD
WESTERN GREAT LAKES TROUGHING FAVORS STREAMS OF MID TO HIGH
LEVEL CLOUDS TODAY FOR AREAS ALONG AND NORTH OF I-70 TODAY.
WHILE THIS GENERALLY LENDS TO A COOLING EFFECT, SURFACE HIGH
PRESSURE OVER THE ATLANTIC COAST WILL SUPPORT WARM ADVECTION
WITHIN SOUTHWEST FLOW INTO THE UPPER OHIO RIVER VALLEY. THE
RESULT: DRY WEATHER TODAY WITH STREAMS OF CLOUDS NORTHWARD WHILE
BELOW NORMAL MORNING TEMPERATURE (AND SINGLE DIGIT TO TEEN WIND
CHILLS) RISES TOWARD SEASONABLE READINGS BY THE AFTERNOON.
THE SHORTWAVE WILL PASS NORTH TONIGHT AND PUSH A DRY SURFACE
COLD FRONT INTO THE REGION DURING THE OVERNIGHT HOURS INTO
SUNDAY. FALLING TEMPERATURE BEHIND THE BOUNDARY IS EXPECTED TO
DROP READINGS TO SEASONABLE LEVELS WITH ENOUGH BREEZINESS FOR
TEENS TO 20S WIND CHILL VALUES.
SHORT TERM /SUNDAY THROUGH MONDAY/
KEY MESSAGES:
- LITTLE TO NO WARMING TEMPERATURE SUNDAY BEHIND COLD FRONT
- RISING TEMPERATURE FOR MONDAY WHILE REMAINING DRY
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COLD, DRY ADVECTION IN THE WAKE OF THE EARLY MORNING COLD FRONT
SUNDAY IS EXPECTED TO CAUSE TEMPERATURE TO STAGNATE (OR EVEN
CONTINUE TO FALL FOR NORTHWEST PA) DURING DAYLIGHT HOURS. THOUGH
NOT FORECASTED, THERE REMAINS A FEW MODELS SUGGESTING ENOUGH
LAKE INFLUENCE FOR LIGHT SNOW OR FLURRIES OVER NORTH OF I-80;
SIMILARLY, ENOUGH MOISTURE RETURN COULD PRODUCE SIMILAR RESULTS
ALONG THE WV HIGHER TERRAIN AS UPSLOPE FLOW BEGINS. OTHERWISE,
DRY CONDITIONS PREVAILS AND WIND CHILLS REMAIN IN THE TEENS TO
20S.
HIGH RISES AND PASSING SURFACE HIGH PRESSURE MONDAY STRONGLY
FAVOR TEMPERATURE REBOUNDING TOWARD SEASONABLE AVERAGE READINGS
WHILE MAINTAIN DRY WEATHER. THE DEGREE OF HEATING MAY END UP
BEING INFLUENCED BY THE THICKNESS OF INCOMING CIRRUS THAT IS
RESULTING FROM WARM, MOIST ADVECTION OCCURRING IN THE NE
QUADRANT OF A DEVELOPING CENTRAL CONUS RIDGE.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
KEY MESSAGES:
- RAIN/SNOW CHANCES MONDAY NIGHT INTO TUESDAY, TRENDING TOWARD
RAIN ONLY
- LATE WEEK PERIOD FAVORING WELL ABOVE NORMAL TEMPERATURE WITH
RAIN CHANCES DEPENDENT ON TIMING OF SHORTWAVES
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WEAK SHORTWAVE MOVEMENT TO THE NORTH AND A NOMINAL SURFACE LOW
LIFTING INTO THE GREAT LAKES WILL FOSTER WARM, MOIST ADVECTION
MONDAY NIGHT INTO TUESDAY. BROAD ASCENT AND WARM FRONTAL LIFT IN
THIS ENVIRONMENT WILL LEAD TO WIDESPREAD PRECIPITATION THAT
COULD START AS EARLY AS MONDAY EVENING BUT IS MORE LIKELY STARTS
EARLY TUESDAY MORNING BEFORE TAPERING OFF LATE TUESDAY NIGHT AS
THE DEEPENING LOW/TROUGH EXIT INTO THE NEW ENGLAND REGION.
ENSEMBLE MEANS CURRENTLY FAVOR A MIX OF RAIN/SNOW AT ONSET (SNOW
FAVORING NW PA AND THE HIGHER TERRAIN) THAT SEES THE TRANSITION
LINE EDGE EASTWARD THROUGH THE DAY AS WARM ADVECTION CONTINUES.
THERE IS VARIABILITY IN THIS SOLUTION AS THE DEGREE OF PRIOR
CLOUD COVER (AND ITS IMPACT TO NOCTURNAL COOLING) OR STRENGTH OF
WARM ADVECTION MAY IMPACT THERMAL PROFILES TO INCREASE/DECREASE
SNOW RISK OR INTRODUCE A FREEZING RAIN RISK (LIKELY ONLY WITHIN
THE HIGHER TERRAIN NORTHWARD TO DUBOIS). ADDITIONALLY, DEGREE OF
WARM ADVECTION PLUS MOISTENING OF THE PRIOR DRY AIRMASS COULD
INTRODUCE WET BULBING THAT AGAIN ALTERS THERMAL PROFILES AND
THUS PRECIPITATION TYPES. BASED ON LATEST MODEL DATA,
PROBABILITIES ARE BULLISH ON LITTLE TO NO SNOW ACCUMULATION
(90-100% PROBABILITY ACROSS REGION OF SEEING LESS THAN 1") BUT
THERE IS A MORE NOTABLE 20% PROBABILITY OF SEEING ACCUMULATING
FREEZING RAIN (0.01" OR GREATER) NEAR THE I-80 CORRIDOR OF
CLARION/JEFFERSON/FOREST COUNTIES.
WEDNESDAY INTO THE REST OF THE WEEK ARE HIGHLY LIKELY TO
TEMPERATURE RISING ABOVE TO WELL ABOVE NORMAL READINGS AS UPPER
RIDGING MOVES INTO THE TENNESSEE RIVER VALLEY. PRECIPITATION
CHANCES WILL BE PERIODIC BUT HAVE FAIRLY HIGH UNCERTAINTY ON
TIMING DUE TO BEING VERY DEPENDENT ON WEAK SHORTWAVE MOVEMENT
WITHIN NW FLOW ALONG THE PERIPHERY OF THE RIDGE AS WELL AS THE
RIDGES RESPONSE (EITHER FLATTENING OR RE-DEVELOPING) TO THE
FIRST OF THESE SHORTWAVES. IT IS BEST TO MONITOR FORECAST TRENDS
FOR HOLIDAY TRAVEL AS POP VALUES MAY FLUCTUATE BETWEEN 6-18
HOUR PERIODS UNTIL MODELS HAVE A BETTER HANDLE ON THE SMALL
SCALE SHORTWAVE FEATURES.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- VFR WITH LLWS OVERNIGHT.
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THERE IS HIGH CONFIDENCE IN VFR THROUGHOUT THE DAY (OR
IMPROVEMENT TO VFR AT DUJ). THIS WILL BE ACCOMPANIED BY A LIGHT
SOUTHERLY WIND, THAT WILL GRADUALLY VEER SOUT-SOUTHWEST
THROUGHOUT THE DAY.
OVERNIGHT, DECOUPLING IS EXPECTED ALONG WITH AN ENHANCED
PRESSURE GRADIENT AS HIGH PRESSURE MOVES TO THE EAST. FURTHER,
LOW-LEVEL WIND SHEAR WAS NOTED FOR NOW WITH DECOUPLING FAVORED
OVER GUSTS.
OUTLOOK...
A PASSING WAVE COULD LOWER CIGS AT DUJ/FKL SUNDAY, WITH A 50/50
CHANCE RESTRICTIONS MAKE IT DOWN TO PIT. WIDESPREAD RESTRICTIONS
RETURN OVERNIGHT MONDAY INTO TUESDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...FRAZIER
NEAR TERM...FRAZIER
SHORT TERM...FRAZIER
LONG TERM...FRAZIER
AVIATION...MILCAREK
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