817
FXUS61 KPBZ 180648
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
148 AM EST THU DEC 18 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN DRY WEATHER THROUGH MUCH OF THE DAY
BEFORE PRECIPITATION RETURNS TONIGHT WITH A CROSSING FRONT.
RAIN WILL CHANGE OVER TO SNOW SHOWERS FRIDAY BEHIND THE FRONT,
AND WINDS WILL BECOME GUSTY.
NEAR TERM /THROUGH TODAY/
KEY MESSAGES:
- DRY WEATHER CONTINUES THROUGH THE DAYTIME HOURS
- DIMINISHING WIND THIS EVENING
-----------------------------------------------------------A
HIGH PRESSURE BUILDING ACROSS THE REGION OVERNIGHT 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 /TONIGHT THROUGH SATURDAY/
KEY MESSAGES:
- RAIN CHANCES INCREASE THIS EVENING
- RAIN TRANSITIONS TO SNOW FRIDAY
- GUSTY WINDS TONIGHT FRIDAY, WITH WIND HEADLINES POSSIBLE IN
THE RIDGES
- DRY AND SEASONABLE SATURDAY
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AS SURFACE HIGH PRESSURE SLIDES EAST OF THE AREA, A DIGGING
SHORTWAVE WILL APPROACH OUT OF THE MIDWEST. THE SURFACE LOW WILL
THEN MOVE ACROSS THE UPPER GREAT LAKES, WHICH WILL BRING
ASSOCIATED PRECIPITATION THIS EVENING (WITH RAIN CHANGING OVER
TO SNOW BY FRIDAY MORNING) BETWEEN 0.30" AND 0.50" OF QPF IS
FORECAST THROUGH FRIDAY EVENING, BUT SNOW ACCUMULATIONS WILL BE
RELATIVELY LIGHT WITH LOW SNOW TO LIQUID RATIOS DURING/AFTER
THE CHANGEOVER AND A SATURATED BOUNDARY LAYER IS LACKING IN THE
DGZ, UNTIL FRIDAY EVENING, BUT BY THEN MOISTURE IS LIMITED.
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 /06Z THURSDAY THROUGH MONDAY/
KEY MESSAGES:
- VFR PREVAILS THROUGHOUT THE PERIOD AT ALL TERMINALS
- BREEZY ESE TO S WIND INCREASES JUST AHEAD/BEHIND FRONTAL
PASSAGE
- RAIN CHANCES AND FRONT TIMING AT END TO JUST AFTER TAF PERIOD
------------------------------------------------------------
HIGH CONFIDENCE IN SURFACE HIGH PRESSURE EAST OF THE REGION
PROMOTING VFR CONDITIONS WITH INCREASING MID TO HIGH LEVEL
CLOUDS THROUGH THE EARLY EVENING AMID STRONG WARM/MOIST
ADVECTION AHEAD OF AN APPROACHING LOW. A NOCTURNAL JET PRIOR TO
DAYBREAK MAY CREATE NEAR LLWS CONDITIONS AT AREA TERMINALS, BUT
CONFIDENCE IS TOO LOW FOR INCLUSION AS CRITERIA WIND MAY OCCUR
ABOVE THE 2KFT THRESHOLD.
STRENGTHENING SURFACE GRADIENT AND MIXING FAVORS ESE TO S WIND
DURING THE DAY THAT MAY FEATURE 15-25KT GUSTS. THESE WINDS WILL
PERSIST AFTER SUNSET/22Z, POTENTIALLY STRENGTHENING DEPENDING
HOW WELL MIXING THE BOUNDARY LAYER REMAIN AS WELL AS
TIMING/PASSAGE OF A SURFACE COLD FRONT. JET AIDED ASCENT AHEAD
OF THE TROUGH AXIS MAY YIELD AREAS OF LIGHT TO BRIEFLY MODERATE
RAIN THAT BEGINS TO LOWER CIGS, BUT FALLS A LIKELY TO BE SLOWER
THAN MODEL DEPICTED DUE TO PRIOR DRY AIRMASS.
MORE WIDESPREAD RAIN, INCLUDING POTENTIAL FOR AN EMBEDDED LINE
OF CONVECTIVE SHOWERS, ARRIVES WITH THE COLD FRONTAL PASSAGE
OCCURING AFTER 02Z (AND NEAR/AFTER THE TAF PERIOD).
OUTLOOK...
ALONG WITH RAIN, THE COLD FRONT THURSDAY NIGHT BRINGS HIGH
LIKELIHOOD FOR MVFR (LOW PROB IFR) CIGS MAINLY AFTER PASSAGE
AMID STRONG COLD ADVECTION. GUSTY WESTERLY WIND IS FAVORED INTO
FRIDAY, PEAKING DURING DAYLIGHT HOURS, AROUND 25-35KTS WITH
STRONGER GUSTS POSSIBLE IN THE HIGHER TERRAIN. ANY LINGERING
PRECIPITATION WILL BE LIGHT AND TRANSITION TO SNOW THROUGH
FRIDAY MORNING, ACCUMULATING MAINLY ON GRASSY SURFACES.
DRY ADVECTION/SUBSIDENCE FAVORS VFR BY FRIDAY NIGHT THAT WILL
PERSIST UNTIL A WEAK FRONTAL PASSAGE LATE SATURDAY INTO SUNDAY
OFFERS LOWER PRECIP/RESTRICTIONS PROBABILITIES.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...WM
AVIATION...FRAZIER
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