716
FXUS61 KPBZ 171659
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1259 PM EDT WED SEP 17 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN WARM AND MOSTLY DRY WEATHER INTO THE
UPCOMING WEEKEND. RAIN CHANCES RETURN TO THE FORECAST NEXT
WEEK, THOUGH THE CHANCE FOR WIDESPREAD WETTING RAIN REMAINS LOW.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- ISOLATED HIGHER ELEVATION SHOWERS END THIS AFTERNOON; DRY
TONIGHT
- CONTINUED ABOVE-NORMAL TEMPERATURES
- AREAS OF FOG POSSIBLE LATE TONIGHT, ESPECIALLY IN VALLEYS
---------------------------------------------------------------
VERTICALLY-STACKED LOW PRESSURE OVER EASTERN VIRGINIA CONTINUES
TO SPIN MAINLY MID AND UPPER-LEVEL MOISTURE INTO OUR EASTERN
COUNTIES TODAY, RESULTING MAINLY IN SOME CLOUD COVER. LIGHT
RADAR RETURNS NEAR THE LAURELS AND NORTHERN WV RIDGES ARE LIKELY
NOT REACHING THE GROUND IN MANY CASES, ALTHOUGH SPRINKLES OR
LIGHT RAIN SHOWERS WILL REMAIN POSSIBLE INTO MID-AFTERNOON ON A
VERY ISOLATED BASIS. THERE SHOULD A MINOR EAST-TO-WEST GRADIENT
WITH AFTERNOON HIGH TEMPERATURES. VALUES AROUND 5 OR SO DEGREES
ABOVE NORMAL ARE FORECAST TO THE SOUTH AND EAST OF PITTSBURGH
WITH THE CLOUDS, WHILE VALUES AROUND 10 DEGREES ABOVE AVERAGE
WILL BE SEEN IN EASTERN OHIO.
THE LOW WILL LIFT ALONG THE ATLANTIC SEABOARD LATER TODAY AND
TONIGHT, DEGRADING INTO AN OPEN WAVE OVER THE NORTHEAST CONUS
BY 12Z THURSDAY. MOST OF THE CLOUD COVER WILL PULL OFF WITH THE
SYSTEM, LEAVING A MOSTLY CLEAR EVENING AND OVERNIGHT PERIOD. THE
COMBINATION OF CLEAR SKY, LIGHT WIND, AND LINGERING SURFACE-
BASED MOISTURE SHOULD LEAD TO A ROUND OF AT LEAST VALLEY-BASED
FOG OVERNIGHT, AND THE HREF IS SHOWING A DECENT SIGNAL FOR SOME
LOCATIONS EAST OF PITTSBURGH, WITH 40-50 PERCENT PROBABILITY OF
0.5 MILE OR LESS VISIBILITY. GOOD RADIATIONAL COOLING CONDITIONS
SHOULD LEAD TO LOW TEMPERATURES CLOSE TO CLIMATOLOGY.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- MOSTLY DRY WEATHER AND ABOVE-NORMAL TEMPERATURES CONTINUE
--------------------------------------------------------------
THE DEPARTING TROUGH KICKS OFF OF THE NEW ENGLAND COAST ON
THURSDAY. MEANWHILE, THE BLOCKING RIDGE CENTERED OVER THE LOWER
MISSISSIPPI VALLEY/WESTERN GREAT LAKES TODAY MAKES SLOW EASTWARD
PROGRESS WITH TIME AND SETS UP SHOP OVER THE MIDDLE AND UPPER
OHIO VALLEY BY FRIDAY. AT THE SURFACE, A WEAK BOUNDARY WILL
LIKELY SETTLE INTO OUR REGION BEFORE STALLING OUT. A FEW MODEL
SOLUTIONS ACTUALLY SPIT OUT SOME LIGHT QPF WITH THIS FRONT
FRIDAY/FRIDAY NIGHT. THE NBM CARRIES SUB-15 POPS THROUGH FRIDAY
NIGHT FOR NOW, AND WILL RIDE WITH THAT GIVEN THE DRY AIRMASS
THAT NEEDS TO BE OVERCOME, AS WELL AS THE DEARTH OF SUPPORT.
PERHAPS SOME MINIMAL PRECIPITATION MENTION MIGHT BE NEEDED ONCE
HIGHER-RES CAMS GET A HOLD OF THE FRONT. SO, THE FORECAST
CONTINUES THE EXTENDED RUN OF DRY WEATHER THROUGH FRIDAY NIGHT.
WARM TEMPERATURES ARE FORECAST ACROSS THE BOARD THURSDAY WITH
PLENTY OF SUN AND BUILDING HEIGHTS, WITH WIDESPREAD HIGHS IN THE
LOWER AND MIDDLE 80S. HIGHS WILL BE A LITTLE MORE SUBDUED NORTH
OF US-422 ON FRIDAY BEHIND THE FRONT, BACKING OFF TO THE UPPER
70S/AROUND 80, WHILE HIGHS TO THE SOUTH REMAIN AROUND 10 DEGREES
ABOVE NORMAL. SIMILAR TRENDS WILL BE SEEN WITH OVERNIGHT LOWS,
ALTHOUGH THEY WILL BE A BIT CLOSER TO CLIMATOLOGY.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGES:
- STILL MOSTLY DRY AND WARMER THAN NORMAL THROUGH THE WEEKEND
- SLIGHT UPTICK IN RAIN CHANCES NEXT WEEK
- TEMPERATURES REMAIN ABOVE NORMAL MONDAY THROUGH WEDNESDAY,
ALBEIT WITH A SLIGHT DOWNWARD TREND
------------------------------------------------------------------
DESPITE THE FRONTAL BOUNDARY WAVERING IN OUR REGION, A LARGELY
DRY PATTERN IS FORECAST FOR SATURDAY AS THE UPPER RIDGE AXIS
CROSSES, WITH HIGH TEMPERATURES SIMILAR TO FRIDAY. HOWEVER,
THERE IS A BIT BETTER POTENTIAL FOR A LIGHT SHOWER OR TWO IN THE
RIDGES SOUTHEAST OF PITTSBURGH, WITH BETTER INDICATIONS OF
MOISTURE AND MODEST LOW-LEVEL CONVERGENCE. STILL, CHANCES OF A
WETTING RAIN FROM THIS ACTIVITY REMAIN UNDER 15 PERCENT, SO ANY
MEANINGFUL DENT IN THE DEVELOPING DROUGHT IS UNLIKELY.
ENSEMBLES/CLUSTER ANALYSIS CONTINUE TO SHOW A SLOWER TREND WITH
THE PROGRESS OF THE NEXT UPSTREAM TROUGH, WITH THE AXIS
PROGRESSING FROM THE UPPER MISSISSIPPI VALLEY ON SUNDAY TO JUST
THE WESTERN/CENTRAL GREAT LAKES BY TUESDAY. SOME SOLUTIONS EVEN
SUGGEST THE DEVELOPMENT OF A CUTOFF UPPER LOW SOMEWHERE OVER THE
EASTERN PLAINS. THIS TREND, IN TURN, RESULTS IN JUST A SLOW
INCREASE TO MINIMAL POPS, WITH SLIGHT CHANCE VALUES NORTHWEST OF
PITTSBURGH SUNDAY NIGHT/MONDAY, BEFORE EVENTUALLY OVERSPREADING
THE AREA TUESDAY/WEDNESDAY. QPF EXPECTATIONS ARE NOT HIGH. THE
NBM SHOWS A 40-60 PERCENT CHANCE OF 0.10" OR MORE DURING THE
72-HOUR PERIOD ENDING AT 12Z THURSDAY. WITH INCREASING RAINFALL
DEFICITS, WE WILL NEED HEALTHIER PRECIPITATION TOTALS TO PUT A
BETTER DENT IN THE DRYNESS.
OVERALL, ABOVE-NORMAL TEMPERATURES CONTINUE TO BE THE
EXPECTATION THROUGH THE MIDDLE OF NEXT WEEK. STILL, WITH THE
SLOWLY FALLING HEIGHTS AND INCREASING CLOUD COVER POTENTIAL, A
MODEST DOWNWARD TREND IS THE MOST LIKELY SCENARIO. THE 25TH-75TH
PERCENTILE SPREADS DO INCREASE THROUGH THIS PERIOD, INDICATING
INCREASING UNCERTAINTY IN THE ULTIMATE VALUES. THIS IS
REASONABLE GIVEN THE RANGE OF POTENTIAL SOLUTIONS WITH THE
UPSTREAM TROUGH.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
A MID-ATLANTIC COASTAL LOW WILL ADVECT ENOUGH MOISTURE EASTWARD
TO CREATE PERIODS OF SCATTERED TO BROKEN MID AND HIGH LEVEL
CLOUDS, FAVORING ABOVE 5KFT. OTHERWISE, SURFACE HIGH PRESSURE
AND LIGHT EASTERLY FLOW IS EXPECTED TO MAINTAIN VFR THROUGH THE
MAJORITY OF THE TAF PERIOD.
HI-RES MODELING SHOWS A SIGNAL OF FOG POTENTIAL THURSDAY
MORNING, FAVORING AREAS EAST OF I-79 AND SOME RIVER VALLEYS.
ENSEMBLE DATA SUGGESTS RESTRICTIONS ARE MORE LIKELY TIED TO
VISIBILITY REDUCTIONS (30-40% PROBABILITIES OF LESS THAN HALF
MILE VISIBILITIES BETWEEN 08Z-12Z) WITH A LOWER LIKELIHOOD OF
STRATUS DEVELOPMENT (20-30% PROBABILITIES FOR IFR CIGS). THIS IS
DUE TO THE COMBINATION OF RESIDUAL SURFACE MOISTURE INFLATING
AREA DEW POINTS AND EVACUATION OF MID/HIGH LEVEL CLOUDS THAT
(COMBINED WITH STAGNANT WIND) BETTER RESULTS IN STRONG
RADIATIONAL COOLING. ONSET OF SUNRISE AND MIXING SHOULD QUICKLY
DISSIPATE ANY FOG/STRATUS BY 14Z THURSDAY.
OUTLOOK.
VFR IS FAVORED UNDER THE INFLUENCE OF HIGH PRESSURE WITH
LOCALIZED RIVER VALLEY MORNING FOG THROUGH SATURDAY. THE
EXCEPTION IS INCREASING PROBABILITIES FOR A WEAK COLD FRONT
SAGGING INTO NORTHWEST PA FRIDAY MORNING THAT MAY LEAD TO MVFR
CIGS (30-50% LIKELIHOOD AT FKL/DUJ).
APPROACH OF AN UPPER LEVEL SHORTWAVE MAY FOSTER LOW PROBABILITY
RAIN/SPRINKLE CHANCES SUNDAY/MONDAY FAVORING LOCATIONS NW OF
PITTSBURGH, BUT VFR IS LIKELY TO PERSIST.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...CL
NEAR TERM...CL
SHORT TERM...CL
LONG TERM...CL
AVIATION...FRAZIER
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