142
FXUS61 KPBZ 171800
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
100 PM EST WED DEC 17 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN DRY WEATHER THROUGH THURSDAY. RAIN
RETURNS THURSDAY NIGHT WITH A CROSSING COLD FRONT. RAIN WILL
CHANGE TO SNOW SHOWERS ON FRIDAY BEHIND THE FRONT, AS WIND
BECOMES GUSTY.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- DRY WEATHER THROUGH TONIGHT
- DIMINISHING WIND THIS EVENING
-----------------------------------------------------------
A WEAKENING SURFACE COLD FRONT WAS LOCATED ACROSS THE LOWER
GREAT LAKES REGION. A BAND OF STRATOCUMULUS CLOUDS WAS
ASSOCIATED WITH THIS FRONT, AND WILL LIKELY OVERSPREAD AREAS
NORTH OF I-80 THROUGH THIS EVENING. THE SOUTHERN EDGE OF THESE
CLOUDS HAVE BEEN ERODING WITH DRY AIR IN PLACE ACROSS THE
REGION.
HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE REGION TONIGHT,
WITH THE LOWER LEVEL CLOUDS DISSIPATING. AREAS OF HIGH CLOUDS
WILL CONTINUE TO CROSS THE AREA AT TIMES OVERNIGHT, WITH WARM
ADVECTION ALOFT. RADIATIONAL COOLING IS EXPECTED AS THE
ATMOSPHERE DECOUPLES OVERNIGHT, WITH LOWS NEAR SEASONABLE
LEVELS.
SHORT TERM /THURSDAY THROUGH SATURDAY/
KEY MESSAGES:
- RAIN LATE THURSDAY/THURSDAY NIGHT
- RAIN TRANSITIONS TO SNOW SHOWERS FRIDAY
- GUSTY WIND THURSDAY NIGHT/FRIDAY, WITH WIND HEADLINES POSSIBLE
IN THE RIDGES
- DRY AND SEASONABLE SATURDAY
----------------------------------------------------------------
SURFACE HIGH PRESSURE WILL SLIDE EAST OF THE AREA ON THURSDAY,
AS A DIGGING SHORTWAVE ADVANCES OUT OF THE MIDWEST. THE
ASSOCIATED SURFACE COLD FRONT IS THEN EXPECTED TO APPROACH AND
CROSS THE REGION LATE THURSDAY AFTERNOON THROUGH FRIDAY NIGHT,
WITH INCREASING RAIN CHANCES FROM W-E. JET SUPPORT IS ALSO
EXPECTED TO ENHANCE ASCENT ACROSS THE REGION AS THE FRONT
CROSSES. IN GENERAL, AROUND A HALF OF AN INCH OF RAIN IS
EXPECTED THROUGH EARLY FRIDAY MORNING. THE LATEST NBM GUIDANCE
INDICATES ONLY 10-40 PERCENT CHANCES OF EXCEEDING THREE
QUARTERS OF AN INCH OF RAIN THROUGH THIS PERIOD.
RAIN IS EXPECTED TO TRANSITION TO SNOW FROM W-E LATE THURSDAY
NIGHT THROUGH FRIDAY MORNING IN COLD ADVECTION AFTER FROPA. SNOW
SHOWERS SHOULD CONTINUE FRIDAY AS THE UPPER TROUGH AXIS CROSSES
THE REGION. THERE IS ALSO EXPECTED TO BE SOME LAKE ENHANCEMENT
FOR AREAS NORTH OF I-80 (WITH LAKE-850MB TEMP DIFFERENTIAL
AROUND -16 DEG C), AND TERRAIN ENHANCEMENT IN THE RIDGES,
THOUGH A WESTERLY BOUNDARY LAYER FLOW IS LESS THAN OPTIMAL FOR
BOTH OF THESE FACTORS ACROSS OUR FORECAST AREA. IN ADDITION,
FULL SATURATION IN THE DENDRITIC LAYER IS LACKING ACROSS THE
HIGHER TERRAIN, WHICH SHOULD HELP LIMIT ACCUMULATIONS.
PROBABILITIES FOR AN INCH OR SO OF SNOW ARE HIGHEST NORTH OF THE
I-80 CORRIDOR AND IN THE RIDGES.
SNOW SHOWERS SHOULD TAPER OFF FRIDAY NIGHT AS SURFACE HIGH
PRESSURE BEGINS TO BUILD IN, AND THE BOUNDARY LAYER FLOW BACKS
TO THE SW. NON DIURNAL TEMPERATURES ARE EXPECTED THURSDAY NIGHT
AND FRIDAY, AS TEMPERATURES FALL INTO THE 20S THROUGH THE DAY.
IN ADDITION, A TIGHTENING PRESSURE GRADIENT AND MIXING IS
EXPECTED TO RESULT IN INCREASING WIND ON THURSDAY. WIND SHOULD
INCREASE FURTHER THURSDAY NIGHT AND FRIDAY WITH STEEPENING LAPSE
RATES IN COLD ADVECTION, WITH GUSTS 30-40 MPH FOR MUCH OF THE
AREA. THE RIDGES OF PA AND WV COULD SEE GUSTS FROM 45 TO 55 MPH,
AND WIND ADVISORIES MAY BE NEEDED. WILL HIGHLIGHT THIS
POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
KEY MESSAGES:
- RAIN/SNOW CHANCES SATURDAY NIGHT
- DRY SUNDAY AND MONDAY
- PRECIPITATION CHANCES RETURN MONDAY NIGHT THROUGH WEDNESDAY
-------------------------------------------------------------------
MODEL ENSEMBLES INDICATE A SHORTWAVE TROUGH WILL CROSS THE
REGION SATURDAY NIGHT INTO EARLY SUNDAY, WITH RAIN AND SNOW
CHANCES EXPECTED. GENERALLY DRY WEATHER RETURNS FOR THE
REMAINDER OF SUNDAY INTO MONDAY AS THE TROUGH EXITS, AND SURFACE
HIGH PRESSURE BUILDS IN. A MILDER PATTERN IS THEN EXPECTED
THROUGH MID WEEK AS THE FLOW ALOFT BECOMES LESS AMPLIFIED.
RAIN/SNOW CHANCES RETURN MONDAY NIGHT THROUGH TUESDAY NIGHT AS A
COUPLE OF WEAK SHORTWAVES EMBEDDED IN THE FLOW CROSS THE REGION.
AFTER COLDER THAN AVERAGE TEMPERATURES SUNDAY AND MONDAY,
READINGS SHOULD THEN BE ABOVE AVERAGE THROUGH MID WEEK.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
KEY MESSAGES:
- GUSTY S-SW WIND DURING THE DAYTIME HOURS
- A PERIOD OF MVFR CIGS FKL AND DUJ THIS AFTERNOON/EVENING,
OTHERWISE VFR THROUGH THURSDAY
------------------------------------------------------------
AREAS OF HIGH LEVEL CLOUDS WILL CONTINUE TO CROSS THE AREA
THROUGH TONIGHT AS WARM ADVECTION REDEVELOPS AHEAD OF AN
APPROACHING SHORTWAVE TROUGH. A WEAKENING COLD FRONT WILL
LIKELY BRING A PERIOD OF MVFR TO FKL AND DUJ THIS AFTERNOON AND
EVENING. THE LEADING EDGE OF THIS CLOUD LAYER HAS BEEN ERODING
WITH DRY AIR IN PLACE, SO IT APPEARS LESS LIKELY THAT THIS LAYER
WILL ADVANCE MUCH FURTHER SOUTH OF I-80 THAN EARLIER
INDICATIONS. GUSTY SW WIND WILL CONTINUE WITH MIXING AND A
TIGHT PRESSURE GRADIENT THROUGH LATE AFTERNOON, BEFORE
DIMINISHING THIS EVENING. BUILDING HIGH PRESSURE RETURNS VFR
FOR ALL PORTS OVERNIGHT.
MID LEVEL CLOUDS WILL INCREASE THROUGH THE DAY THURSDAY AHEAD OF
AN APPROACHING COLD FRONT. SOUTH WIND SHOULD ALSO GUST FROM
15-20KT AS THE PRESSURE GRADIENT AGAIN INCREASES. KEPT LLWS OUT
OF THE TAFS AT THIS TIME, AS IT APPEARS GUSTS WILL BEGIN AS
STRONGER LOW LEVEL WINDS TRACK ACROSS THE AREA.
OUTLOOK...
WIDESPREAD RESTRICTIONS ARE EXPECTED THURSDAY NIGHT IN RAIN
WITH THE APPROACH AND PASSAGE OF A COLD FRONT. GUSTY WIND AND A
TRANSITION TO SNOW IS EXPECTED ON FRIDAY WITH UPPER TROUGHING
BEHIND THE FRONT, AND COLD WNW FLOW OFF OF THE GREAT LAKES.
GENERAL VFR IS THEN EXPECTED THROUGH MUCH OF THE WEEKEND,
THOUGH A WEAK COLD FRONT SHOULD BRING AN INCREASE IN CLOUD COVER
ALONG WITH RAIN/SNOW CHANCES SATURDAY NIGHT AND SUNDAY. VFR IS
EXPECTED MONDAY UNDER HIGH PRESSURE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...WM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page