977
FXUS61 KPBZ 040733
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
233 AM EST THU DEC 4 2025
SYNOPSIS
A FRONTAL PASSAGE THIS MORNING PROVIDES A LIGHT SNOW
ACCUMULATION AND A REINFORCING SHOT OF COLD AIR. RECORD-LOW
TEMPERATURES ARE POSSIBLE TONIGHT IN SOME AREAS. ADDITIONAL
LIGHT SNOW CHANCES AND BELOW-NORMAL TEMPERATURES SHOULD
CONTINUE INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TODAY/
KEY MESSAGES:
- ARCTIC COLD FRONT ARRIVING LATE TONIGHT WITH SOME SNOW
- THREAT OF REFREEZING ON ROADS FOR THE MORNING COMMUTE
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A MID-LEVEL SHORTWAVE OVER ONTARIO IS SET TO SWING INTO QUEBEC
AND NORTHERN NEW ENGLAND TODAY. A LONG COLD FRONT EXTENDING FROM
CANADA INTO THE LOWER OHIO VALLEY WILL DROP THROUGH OUR REGION
THIS MORNING. MOISTURE REMAINS SCANT, WITH PRECIPITABLE WATER
REACHING A SEASONALLY-APPROPRIATE LEVEL OF AROUND 0.4 INCH WITH
FROPA. LIFT PROVIDED BY THE BOUNDARY AND SOME MODEST JET-AIDED
ASCENT SHOULD PROVIDE A ROUND OF MOSTLY LIGHT SNOW AS THE
BOUNDARY DROPS ACROSS. SNOW TO THIS POINT HAS BEEN LIMITED TO
AREAS NORTH OF I-80 THUS FAR, AND WILL CONTINUE TO ADVANCE
SOUTHEAST THROUGH THE MORNING. PEAK ACCUMULATION RATES (0.25"
INCH AN HOUR OR SO) ARE LIKELY TO OCCUR DURING THE MORNING
COMMUTE. OVERALL TOTALS WILL BE LIGHT, GENERALLY LESS THAN AN
INCH (SAVE FOR PERHAPS THE LAUREL RIDGES, WHICH HAVE A 40-50
PERCENT CHANCE OF REACHING THAT THRESHOLD WITH SOME UPSLOPE
CONTRIBUTION). HOWEVER, GIVEN THE TIMING AND THE SNOW LIKELY TO
STICK TO UNTREATED COLD SURFACES, SOME IMPACTS TO ROAD TRAVEL
ARE LIKELY. A SPECIAL WEATHER STATEMENT HIGHLIGHTING THIS
POTENTIAL HAS ALREADY BEEN ISSUED AND WILL BE MAINTAINED.
ONE THING TO WATCH FOR WILL BE THE POTENTIAL FOR PRECIPITATION
TO TAPER TO SPOTTY FREEZING DRIZZLE AT TIMES. THERE IS SOME
INDICATION OF THIS IN CENTRAL OHIO, WITH SOME REPORTS OF 5-7
MILE VISIBILITY IN MIST WITH SUBFREEZING TEMPERATURES. THIS IS
DUE TO THE SHALLOW NATURE OF THE MOISTURE, WITH THE AREA OF
SATURATION TOPPING OUT IN THE -10C TO -12C LAYER OF MODEL
SOUNDINGS, WHICH BRINGS THE PRESENCE OF ICE CRYSTALS INTO
QUESTION. DO NOT THINK THAT THIS WILL BE A WIDESPREAD OR HIGHLY
IMPACTFUL OCCURRENCE, AND THE ROAD IMPACTS ARE LARGELY ALREADY
COVERED BY THE SPS, BUT THIS WILL BE MONITORED.
ALTHOUGH A FEW SNOW SHOWERS MAY LINGER TEMPORARILY NORTH OF I-80
IN LAKE-ENHANCED NORTHWEST FLOW, SNOW WILL LARGELY CEASE BY
EARLY AFTERNOON AS THE SHORTWAVE AND FRONT RAPIDLY DEPART.
CLOUDS WILL ALSO ERODE WITH TIME, LEADING TO MOSTLY CLEAR
CONDITIONS FOR MANY AREAS BY SUNSET. STRONG COLD ADVECTION
SHOULD LEAD TO A NON-DIURNAL TEMPERATURE CURVE, WITH
MORNING/MIDDAY HIGHS IN THE UPPER 20S/LOWER 30S FOLLOWED BY
FALLING AFTERNOON TEMPERATURES. BLUSTERY WIND WILL ALSO BE
FAVORED BEHIND THE FRONT AS LAPSE RATES STEEPEN, WITH GUSTS UP
TO 25 MPH IN THE LOWLANDS AND UP TO 35 MPH IN THE HIGHER
TERRAIN. THIS WIND WILL FOSTER WIND CHILL VALUES DROPPING
THROUGH THE TEENS AND LOWER 20S THIS AFTERNOON.
SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- NEAR-RECORD LOW TEMPERATURES THURSDAY MORNING.
- LOW CONFIDENCE IN SNOW FRIDAY.
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HIGH PRESSURE CROSSES THE UPPER OHIO VALLEY TONIGHT. THE EVENING
HOURS HAVE THE BEST CHANCE OF PROVIDING MORE IDEAL RADIATIONAL
COOLING CONDITIONS WITH A MOSTLY CLEAR SKY, DIMINISHING WIND,
AND A SNOWPACK. THE QUESTION FOR THE OVERNIGHT PERIOD IS HOW
MUCH CLOUD COVER CAN REESTABLISH FROM THE SOUTH. ECMWF ENSEMBLE
MEMBERS HAVE BACKED OFF A BIT ON THE CLOUD INCREASE AS COMPARED
TO PREVIOUS RUNS, BUT ARE STILL A BIT FURTHER NORTH THAN
GEFS/GEPS, WHICH KEEP CLOUDS MAINLY CONFINED TO AREAS NEAR AND
SOUTH OF THE MASON-DIXON LINE. THIS OF COURSE HAS IMPLICATIONS
FOR OVERNIGHT LOW TEMPERATURES, WHICH COULD BE RECORD-BREAKING
IN A FEW CASES (SEE CLIMATE SECTION). AREAS NORTH OF THE WV/PA
BORDER AWAY FROM URBAN AREAS/RIVER VALLEYS HAVE A 50 TO 80
PERCENT CHANCE OF SEEING LOWS IN THE SINGLE DIGITS, WHILE OTHER
AREAS ARE STILL LIKELY TO FALL INTO THE 10 TO 15 RANGE.
GENERALIZED ZONAL FLOW OVER THE OHIO VALLEY ON FRIDAY WILL BE
MARRED SLIGHTLY BY A FLAT MID-LEVEL WAVE, WITH A SURFACE
REFLECTION TRACKING ACROSS THE DEEP SOUTH. THE MOST LIKELY
SCENARIO REMAINS A ROUND OF LIGHT SNOW FOR THE WV RIDGES OF
UNDER AN INCH. THE TOTAL RANGE OF SCENARIOS RUN FROM A FAR
SOUTH STORM TRACK WITH NO SNOW AT ALL IN THE FORECAST AREA, TO
A PARTIAL RECURVE ALONG THE ATLANTIC COAST THAT COULD PUSH LIGHT
SNOW AS FAR NORTH AS PITTSBURGH, AND PROVIDE A FEW INCHES TO
THE RIDGES OF PRESTON/TUCKER COUNTIES. GIVEN THE PATTERN, THE
FORMER SEEMS LIKE A MORE REASONABLE OUTCOME THAN THE LATTER.
ANY SNOW WOULD DEPART BY SUNSET, LEAVING A DRY AND COLD FRIDAY
NIGHT.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- BELOW NORMAL TEMPERATURES CONTINUE EARLY NEXT WEEK.
- MORE WINTER WEATHER POTENTIAL.
-------------------------------------------------------------------
THE TROUGHING PATTERN CONTINUES THROUGH THE EXTENDED PERIOD,
PROMISING A CONTINUATION OF BELOW-NORMAL TEMPERATURES.
SHORTWAVES MOVING THROUGH THE FLOW WILL PROVIDE A COUPLE CHANCES
FOR SNOW SHOWER ACTIVITY FROM SATURDAY THROUGH MONDAY, WITH SOME
MINOR TIMING/STRENGTH DIFFERENCES IN THE ENSEMBLE GUIDANCE. IN
ANY CASE, THERE IS GENERALLY A 20 TO 50 PERCENT CHANCE ACCORDING
TO THE NBM OF A TOTAL SNOW ACCUMULATION OF ONE INCH OR MORE
THROUGH THE PERIOD. THE HIGHEST CHANCES OF ANY ACCUMULATIONS
WOULD BE FOR THE PA/WV RIDGES, AND THE LOWEST WOULD BE IN
EASTERN OHIO. A REINFORCEMENT OF COLD TEMPERATURES APPEARS
LIKELY; MAXIMUM VALUES IN THE 30S SATURDAY/SUNDAY HAVE A 70
PERCENT CHANCE OR GREATER OF FALLING BELOW FREEZING ON MONDAY.
MID-TO-LATE WEEK TEMPERATURE UNCERTAINTIES WOULD BE MORE TIED
TO AMPLITUDE UNCERTAINTY OF THE SEMI-PERSISTANT EASTERN TROUGH.
A STRONGER PREVAILING TROUGH WOULD ALLOW FOR COOLER CONDITIONS,
WITH HIGHER CHANCES OF LOW-QPF SNOWFALL. A WEAKER TROUGH WOULD
LIKELY CORRELATE TO WARMER CONDITIONS WITH HIGHER QPF POTENTIAL
IN MIXED PRECIPITATION EVENTS.
AVIATION /06Z THURSDAY THROUGH MONDAY/
KEY MESSAGES:
- MVFR CEILINGS TONIGHT WITH LIGHT SNOW RETURNING AFTER 09Z
- IFR CIGS EXPECTED/VIS POSSIBLE WITH HEAVIER SNOW SHOWERS
- MODELS MORE PESSIMISTIC ON CLEARING THURSDAY AFTERNOON
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THE COLD FRONT ITSELF IS JUST NOW BEGINNING TO CROSS LAKE ERIE.
LIGHT SNOW HAS BEGUN AT FKL BUT WITH SLOWER FRONTAL MOVEMENT,
KICKED BACK SNOW ONSET TIMES AT MOST PORTS. MVFR CIGS AREAWIDE
ARE EXPECTED TO SLOWLY DEGRADE DOWN TO AN IFR/MVFR MIX NEAR 1KFT
OVER THE COMING HOURS AS LIGHT SNOW SLOWLY BEGINS TO OVERSPREAD
THE REGION. ANY HEAVIER SNOW SHOWERS CAN BRING BRIEFLY REDUCED
VIS AND CIG, THIS HAS BEEN INCLUDED AS TEMPOS FOR MOST PORTS
SAVE FOR MGW WHICH MAY BE FAR ENOUGH SOUTH TO AVOID SNOWFALL.
SNOW IS EXPECTED TO TRAIL OFF BY MID MORNING AS WINDS PICK UP
BEHIND THE FRONT. MOST PORTS CAN SEE NWERLY GUSTS BETWEEN 15-20
KNOTS. MODELS HAVE GROWN SLIGHTLY MORE PESSIMISTIC ON A QUICK
CLEARING OF CIGS THIS AFTERNOON AND PROBABILITIES FOR MVFR CIGS
REMAINING AT 18Z ARE LARGELY NORTH OF 80% BESIDES AT ZZV. THESE
PROBABILITIES SLOWLY ERODE THIS EVENING BUT REMAIN BETWEEN
30-50% AT MANY PORTS THROUGH 00Z. FKL/DUJ ARE LIKELY TO HOLD
ONTO MVFR CIGS THE LONGEST.
OUTLOOK... VFR BEGINS TO BECOME THE RULE NOT THE EXCEPTION BY
EARLY FRIDAY MORNING AS HIGH PRESSURE BUILDS IN BEHIND THE
FRONT. RESTRICTIONS ARE POSSIBLE AGAIN SATURDAY AND SUNDAY WITH
A CROSSING COLD FRONT.
CLIMATE
AT LEAST FOUR OF OUR CLIMATE SITES HAVE A CHANCE TO CHALLENGE
RECORD LOW TEMPERATURES FOR DECEMBER 5 ON FRIDAY MORNING. TWO
OTHER SITES ARE LESS LIKELY TO APPROACH THEIR RECORD LOWS.
CURRENT 12/5 FORECAST
SITE RECORD LOW LOW
---- ---------- ------------
PITT INTL 12 (1976) 11
MORGANTOWN 11 (1974) 14
DUBOIS 10 (1991) 7
WHEELING 12 (1944) 12
ZANESVILLE 3 (1957) 11
NEW PHILADELPHIA 2 (1966) 9
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...CL
NEAR TERM...CL
SHORT TERM...CL
LONG TERM...CL/MILCAREK
AVIATION...AK
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