392
FXUS61 KPBZ 020203
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
903 PM EST MON DEC 1 2025
SYNOPSIS
WIDESPREAD PRECIPITATION EXPECTED LATE TONIGHT THROUGH TUESDAY
MORNING, WITH IMPACTFUL SNOW ACCUMULATION FOR MUCH OF THE
REGION. AFTER A BRIEF BREAK TUESDAY NIGHT INTO WEDNESDAY, AN
ACTIVE WEATHER PATTERN AND BELOW-NORMAL TEMPERATURES CONTINUE
INTO NEXT WEEKEND.
NEAR TERM /THROUGH TUESDAY/
KEY MESSAGES:
- A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE ENTIRE
AREA FROM MIDNIGHT UNTIL 1 PM TUESDAY
- WIDESPREAD SNOWFALL ACCUMULATIONS OF 2-5 INCHES, ESPECIALLY
NORTH OF I-70. HEAVIEST SNOWFALL RATES OCCUR BETWEEN 4 AM AND
9 AM, IMPACTING THE MORNING COMMUTE
- MIXED PRECIPITATION IN THE MON VALLEY AND THE RIDGES OF SW PA
AND NORTHERN WV, INCLUDING A CHANCE FOR LIGHT ICE ACCUMULATION
DUE TO PERIODS OF FREEZING RAIN
- PRECIPITATION ENDS FROM WEST TO EAST BY LATE MORNING OR EARLY
AFTERNOON TUESDAY
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AN UPPER TROUGH WILL SWING INTO THE MIDDLE OHIO VALLEY EARLY
THIS MORNING AND INTO THE APPALACHIANS BY THIS EVENING. MODELS
HAVE SHOWN GOOD CONTINUITY OVER THE PAST COUPLE RUNS REGARDING THE
TRACK OF THE ASSOCIATED SFC LOW UP THE ATLANTIC COAST THROUGH
THE PERIOD TO JUST SOUTH OF CAPE COD BY EARLY WEDNESDAY EVENING.
THIS TRACK STILL PRESENTS SOME PRECIPITATION TYPE ISSUES, MAINLY
IN THE RIDGES AND SOME LOCATIONS SOUTH OF I-70. HOWEVER, MUCH
OF THE REGION SHOULD SEE MOSTLY SNOW FROM THIS SYSTEM, WITH
IMPACTFUL ACCUMULATIONS QUITE LIKELY DURING THE MORNING
COMMUTE.
PRECIPITATION WILL BEGIN TO ARRIVE IN EARNEST SHORTLY AFTER
MIDNIGHT AND SHOULD OVERSPREAD THE REGION BY 09Z OR SO. MOST
LOCATIONS SHOULD BEGIN AS SNOW. MODELS CONTINUE TO BE MOST
AGGRESSIVE WITH 850MB WARM ADVECTION SOUTH OF THE MASON-DIXON
LINE AND UP THE SPINE OF THE LAURELS. IT IS HERE WHERE FREEZING
RAIN IS MOST LIKELY, AND IN A RELATED SENSE, WHERE SNOW-TO-
LIQUID RATIOS WILL REMAIN LOWER. ICING OF A LIGHT GLAZE IS
EXPECTED IN SPOTS HERE, PERHAPS UP TO 0.10 INCH IN PORTIONS OF
THE WV RIDGES. FURTHER WEST AND SOUTH OF I-70, WARMING IS NOT AS
STRONG, AND AS SUCH, FREEZING RAIN SHOULD BE SPOTTIER, WITH
PERHAPS ISOLATED INSTANCES OF SLEET WHERE MELTING ALOFT IS LESS
COMPLETE. ALL IN ALL, PORTIONS OF THE MONONGAHELA VALLEY AND THE
LOWLANDS IMMEDIATELY ADJACENT TO THE LAURELS IN SW PA MAY SEE
THE LOWEST SNOW TOTALS FROM THIS EVENT, WITH EVEN SOME RAIN
MIXING IN BY THE TAIL END.
NORTH OF I-70, SNOW ACCUMULATIONS IN THE 3 TO 5 INCH RANGE
CONTINUE TO BE SUGGESTED WITH STORM TOTAL LIQUID EQUIVALENT IN
THE 0.20 TO 0.40 RANGE AND SLRS IN THE RANGE OF 10:1 TO 14:1.
NBM PROBABILITIES FOR 3 INCHES OR MORE HAVE INCREASED TO THE 60
TO 80 PERCENT RANGE ACROSS MOST OF THIS REGION, LOWER IN AREAS
MENTIONED ABOVE WHERE A WINTRY MIX AND RAIN MAY LIMIT
ACCUMULATIONS. PROBABILITIES DROP OFF QUICKLY WITH HIGHER
AMOUNTS, THOUGH THE LATEST RUN DOES SUGGEST A 30 TO 50 PERCENT
CHANCE FOR MORE THAN 5 INCHES IN AREAS NORTHEAST OF PITTSBURGH.
MEANWHILE, THE HREF CONTINUES TO SUGGEST STEADY HOURLY SNOWFALL
RATES IN THE 0.5 TO 0.8 INCH RANGE DURING THE PREDAWN HOURS, AT
A TIME WHEN JET-AIDED SUPPORT FOR VERTICAL MOTION IS MAXIMIZED.
IN THE 4 AM TO 9 AM TIMEFRAME, WHEN FRONTOGENETICALLY-FORCED
BANDING IS POSSIBLE, NEIGHBORHOOD PROBABILITIES FOR 1"/HOUR
RATES GET INTO THE 30-50 PERCENT RANGE. THIS OF COURSE POSES THE
GREATEST POTENTIAL IMPACT TO THE AREA, AS THESE HEAVIER RATES
COINCIDE WITH THE TUESDAY MORNING COMMUTE.
A WINTER WEATHER ADVISORY CONTINUES FOR THE ENTIRE FORECAST
AREA FROM MIDNIGHT TO 1 PM TUESDAY. MUCH OF THE REGION WILL SEE
THE 3 INCH SNOW CRITERIA, WHILE LOCATIONS THAT DO NOT ARE
EXPECTED TO SEE AT LEAST LIGHT ICING. EVEN IF ICE/SNOW
ACCUMULATIONS ULTIMATELY COME IN BELOW CRITERIA, THE FACT THAT
THE HEAVIEST HOURLY RATES ARE FORECAST TO ALIGN WITH THE TUESDAY
MORNING COMMUTE JUSTIFIES THE ISSUANCE OF THE ADVISORY.
STEADY PRECIPITATION WILL WRAP UP FROM WEST TO EAST DURING THE
LATE MORNING AND EARLY AFTERNOON AS THE SURFACE LOW RACES INTO
THE ATLANTIC. PRECIPITATION MAY LINGER LONGEST NEAR AND NORTH
OF I-80 AS WELL AS IN THE RIDGES WITH A BRIEF PUSH OF NW FLOW,
BUT ADDITIONAL ACCUMULATION SHOULD NOT BE AS IMPACTFUL. IF
AFTERNOON ACCUMULATIONS TREND UPWARD IN THESE AREAS OVER THE
NEXT 12-24 HOURS, A LOCAL EXTENSION OF THE ADVISORY MAY BE
NEEDED. BACKING WIND WILL BRING ANY LINGERING ACTIVITY TO AN
END BY 00Z WEDNESDAY.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
KEY MESSAGES:
- DRY AND COLD TUESDAY NIGHT AND WEDNESDAY
- CHANCE FOR LOW SNOW ACCUMULATIONS ON THURSDAY WITH A COLD FRONT
PASSAGE.
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DRY AND CHILLY WEATHER IS FORECAST FOR THE BULK OF TUESDAY NIGHT AND
WEDNESDAY AS SURFACE RIDGING ONCE AGAIN VISITS THE UPPER OHIO
VALLEY. AREAS NEAR AND SOUTH OF PITTSBURGH STAND THE BEST CHANCE OF
SEEING A FAIR BIT OF SUNSHINE BY THE AFTERNOON/EARLY EVENING HOURS
ON WEDNESDAY.
DURING THE DAY WEDNESDAY, A SURFACE LOW PRESSURE DEEPENS OVER
SOUTHERN HUDSON BAY WITH A TROUGH EXTENDING SOUTHWESTWARD TO THE
NORTHWESTERN GREAT LAKES. IT IS EXPECTED TO SLOWLY MOVE EASTWARD
INTO NORTHERN QUEBEC OVERNIGHT WEDNESDAY INTO THURSDAY MORNING WITH
THE SOUTHERN EDGE OF THE TROUGH EXTENDING INTO EASTERN OHIO. THIS
TROUGH WILL BE ASSOCIATED WITH A COLD FRONT THAT WILL MOVE THROUGH
THE REGION BRINGING A REINFORCING SHOT OF COLD AIR.
THERE WILL BE SOME SNOW WITH THIS FRONTAL PASSAGE, HOWEVER, MOISTURE
APPEARS LIMITED WITH THE BEST SYNOPTIC SUPPORT REMAINING TO OUR
NORTHEAST. ENSEMBLES ARE SHOWING SURFACE NORTHWESTERLY FLOW WHICH
HINTS AT SOME OROGRAPHICALLY ENHANCED SHOWERS ALONG THE WESTERN
APPALACHIANS RESULTING IN A HIGHER PROBABILITY FOR MEASURABLE SNOW.
THE NBM SHOWS THERE IS A 40% TO 50% CHANCE FOR >0.50" OF SNOW ON THE
RIDGES AND A 35%-45% CHANCE FOR >0.75" FOR AREAS NORTH OF I-80. FOR
REGIONS SOUTH AND WEST OF THESE AREAS, THERE ARE LOWER PROBABILITIES
FOR RECEIVING UP TO 0.50" OF SNOW.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
KEY MESSAGES:
- PRECIPITATION CHANCES FOR FRIDAY INTO THE WEEKEND
- BELOW AVERAGE TEMPERATURES THROUGH THE PERIOD
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ANOTHER BRIEF DRY INTERLUDE UNDER HIGH PRESSURE IS POSSIBLE THURSDAY
NIGHT INTO EARLY FRIDAY. CALM WIND AND MOSTLY CLEAR SKIES WILL AID
IN TEMPERATURES DROPPING INTO THE LOW TEENS OVERNIGHT. ANOTHER
SYSTEM NEAR SOUTHERN HUDSON BAY ON FRIDAY WILL SLOWLY SWING
SOUTHEASTWARD TO THE EASTERN SEABOARD. THE EXACT TRACK OF THIS
SYSTEM WILL DETERMINE EXACT PRECIP TYPE AND SNOWFALL AMOUNTS, BUT AT
THIS TIME IT LOOKS LIKE WINTRY WEATHER COULD BE WITH US THROUGH THE
WEEKEND.
TEMPERATURES ARE LIKELY TO REMAIN BELOW AVERAGE THROUGHOUT THE
PERIOD. DAYTIME HIGHS IN THE LOW TO MID 30S ON FRIDAY WITH SOME
SLIGHT MODERATION BY THE WEEKEND.
AVIATION /01Z TUESDAY THROUGH SATURDAY/
KEY MESSAGES:
- SNOW ARRIVES AFTER 06Z BRINGING WIDESPREAD IFR AND LOWER
RESTRICTIONS AREAWIDE
- PERIOD OF WORST CONDITIONS LIKELY BETWEEN 08Z-14Z
- SOUTHEASTERLY WIND VEERS NORTHWESTERLY BY TUESDAY AFTERNOON
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A LOW STRATOCU DECK WITH DAYTIME MIXING HAS DISSIPATED WITH
SUNSET THIS EVENING GIVING WAY TO INCREASING UPPER LEVEL CLOUDS
AHEAD OF APPROACHING LOW PRESSURE THAT WILL BRING WIDESPREAD IFR
OR LOWER RESTRICTIONS WITH SNOW STARTING OVERNIGHT MONDAY NIGHT.
A COASTAL LOW MOVING UP THE EASTERN SEABOARD FROM GA/SC TO NEAR
CAPE COD WILL BRING IMPACTS THE REGION TONIGHT INTO TUESDAY IN
THE FORM OF WIDESPREAD ACCUMULATING SNOW (INCLUDING SOME MIXED
PRECIP FOR THE MON VALLEY). DON'T EXPECT IT'LL TAKE LONG FOR
CIGS TO COME DOWN AFTER ONSET OF SNOW, AND VIS WILL QUICKLY DROP
AS WELL AS THE LOWER LEVELS SATURATE. THE HEAVIEST SNOWFALL IS
EXPECTED TO OCCUR DURING THE 08Z-14Z TUESDAY TIMEFRAME, DURING
WHICH THE BROADER HOURLY SNOWFALL RATES WILL RANGE FROM 0.5 TO 1
INCHES PER HOUR. IN PARTICULAR, THE LATEST HI-RES GUIDANCE
CONTINUES TO SUGGEST THE POTENTIAL FOR ONE OR MORE EMBEDDED
SW/NE ORIENTED BANDS DURING THAT TIMEFRAME, IN WHICH THERE IS A
30-50% CHANCE FOR HOURLY SNOWFALL RATES TO LOCALLY EXCEED 1
IN/HR. HAVE ACCORDINGLY BROUGHT PREVAILING IFR VIS AND CIG WITH
TEMPOS LOWER ON BOTH DURING THE PERIOD OF EXPECTED HEAVIEST
SNOWFALL RATES.
WIDESPREAD PRECIPITATION ENDS FROM WEST TO EAST TUESDAY MORNING,
ROUGHLY 13Z-15Z FOR EASTERN OH AND THE WV PANHANDLE AND 15Z-18Z
ACROSS WESTERN PA. SOME LIGHT SNOW MAY LINGER, ESPECIALLY FOR
FKL/DUJ/LBE/MGW, AND CIGS WILL GRADUALLY RISE TO MVFR WITH IFR
PROBABILITY SLOWLY DECREASING INTO THE AFTERNOON HOURS.
WIND WILL TAKE ON A SOUTHEASTERLY COMPONENT INTO TUESDAY MORNING
EVENTUALLY VEERING TO NORTHWESTERLY BY THE AFTERNOON.
OUTLOOK...
GRADUAL CEILING IMPROVEMENT IS EXPECTED THEREAFTER INTO
WEDNESDAY. ADDITIONAL LIGHT SNOW CHANCES AND RESTRICTIONS ARE
POSSIBLE AGAIN WEDNESDAY NIGHT INTO THURSDAY MORNING (FAVORING
LOCATIONS NORTH OF PIT) AND DURING THE DAY FRIDAY (FAVORING
LOCATIONS SOUTH OF PIT).
PBZ WATCHES/WARNINGS/ADVISORIES
PA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
TUESDAY FOR PAZ007>009-013>016-020>022-029-031-073>078.
OH...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
TUESDAY FOR OHZ039>041-048>050-057>059-068-069.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
TUESDAY FOR WVZ001>004-012-021-509>514.
SYNOPSIS...CL
NEAR TERM...CERMAK/CL/88
SHORT TERM...LUPO
LONG TERM...LUPO
AVIATION...CERMAK/MLB
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