663
FXUS61 KPBZ 150627
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
127 AM EST FRI NOV 15 2024
SYNOPSIS
INTERMITTENT DRIZZLE AND OR LIGHT RAIN WILL CONTINUE TODAY,
ALONG WITH EXTENSIVE CLOUD COVERAGE.
NEAR TERM /THROUGH TODAY/
KEY MESSAGES:
- LIGHT RAIN/ DRIZZLE WILL LINGER TODAY.
- ANOTHER DAY WITH LIMITED DIURNAL RANGE IN TEMPERATURE.
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AMPLE LOW LEVEL MOISTURE AND SLIGHT LIFT WILL SUPPORT CONTINUED
PATCHES OF DRIZZLE AND THICK LOW OVERCAST STRATUS TODAY, WHICH
WILL ALSO RESULT IN A LIMITED CHANGE IN AREA TEMPERATURES. 10TH
PERCENTILE NBM GUIDANCE WAS USED FOR DAYTIME HIGHS GIVEN
YESTERDAY'S PERFORMANCE UNDER SIMILAR CONDITIONS.
SHORT TERM /TONIGHT THROUGH SUNDAY/
KEY MESSAGES:
- DRYING AND WARMING TREND BEGINS FRIDAY AND LASTS THROUGH THE
WEEKEND
- ISOLATED, LOW-PROBABILITY SHOWERS ARE POSSIBLE ON FRIDAY
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MID-LEVEL LOW SHIFTS OFF THE COAST BY MIDDAY FRIDAY, VEERING
FLOW TO THE NORTHWEST, ALLOWING FOR THE DEVELOPMENT OF ISOLATED
AND LIGHT LAKE-ENHANCED SHOWERS DURING THE DAY AND POSSIBLY
OVERNIGHT. OVERALL PROBABILITY IS LOW, THOUGH HIGHEST
PROBABILITIES ARE NORTHWEST OF PITTSBURGH AND ACROSS THE RIDGES
WITH UPSLOPING. THE MORE SENSIBLE IMPACT OF NORTHWEST FLOW AND
LINGERING MOISTURE WILL BE CONTINUED OVERCAST CONDITIONS THROUGH
FRIDAY AND INTO SATURDAY. BUILDING HIGH PRESSURE ACROSS THE
GREAT LAKES BY FRIDAY EVENING SHOULD HELP RETURN DRY WEATHER TO
THE AREA THROUGH THE WEEKEND.
DESPITE OVERCAST SKIES, HEIGHT RISES SHOULD BOOST HIGH
TEMPERATURES JUST ABOVE AVERAGE ON FRIDAY, WARMING ANOTHER
DEGREE OR SO ON SATURDAY. UPPER RIDGING BUILDS DIRECTLY OVERHEAD
BY SUNDAY WITH A MODEST BOOST TO WARM ADVECTION SATURDAY INTO
SUNDAY. THIS WILL HELP DRIVE TEMPERATURES BACK INTO THE UPPER
50S TO LOWER 60S ON SUNDAY AFTERNOON.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
KEY MESSAGES:
- HIGHS A FEW DEGREES ABOVE NORMAL FOR THE WEEKEND
- RAIN RETURNS TUE/WED WITH ADDITIONAL CHANCES THROUGH LATE WEEK
- HIGH UNCERTAINTY REMAINS WITH A LATE WEEK SYSTEM
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ENSEMBLES SHOW A BETTER AGREEMENT MONDAY INTO TUESDAY FOR A
FLATTENED RIDGE OVERHEAD AND MILD WEATHER CONTINUING.
TEMPERATURES SHOULD GENERALLY WARM A COUPLE DEGREES EACH DAY,
ENDING UP NEARLY 10 DEGREES ABOVE AVERAGE BY TUESDAY.
GREATER UNCERTAINTY ARISES BY TUESDAY AS A SHORTWAVE EJECTS OUT
OF THE SOUTHWEST AND INTO MIDWEST. THIS WEAKENING WAVE MAY BRING
SHOWERS TO THE AREA BY TUESDAY AFTERNOON THOUGH IT APPEARS THAT
SIGNIFICANT RAIN CHANCES WILL BE SLOW TO MOVE EAST FROM THE
CENTRAL US AS ENSEMBLES HINT AT BLOCKING WITH THE LONGWAVE
TROUGH REMAINING ANCHORED SOMEWHERE NEAR NM TO TX AREA.
CONSIDERABLE UNCERTAINTY ENTERS THE FORECAST BY LATE WEEK,
HIGHLY DEPENDENT ON THE EVOLUTION OF LOW PRESSURE OVER THE GREAT
LAKES AND OHIO VALLEY REGIONS. THERE IS LOW POTENTIAL FOR A
STRONGER SYSTEM, WHICH COULD BRING SNOW CHANCES TO THE AREA,
HOWEVER, OTHER SOLUTIONS (E.G. WEAKER WAVE) SHOW HIGHER
PROBABILITY AT THIS TIME. DAILY TEMPERATURES WILL ALSO BE
CLOSELY TIED TO THE EVOLUTION OF THIS SYSTEM, SO HAVE KEPT CLOSE
TO NBM MEAN VALUES FOR NOW.
AVIATION /07Z FRIDAY THROUGH TUESDAY/
LINGERING MOISTURE IN THE REGION PLUS THE SLOW EXIT OF THE UPPER
TROUGH WILL MAINTAIN MVFR TO IFR CIGS WITH POCKETS OF LIGHT
RAIN/DRIZZLE AND ITS ASSOCIATED VSBY DROPS. A LATE MORNING TO
THE AFTERNOON WIND SHIFT WITH A WEAK FRONTAL BOUNDARY MAY
BRIEFLY DISRUPT CIGS WITH SOME LIFT, BUT MODEL SOUNDINGS SUGGEST
ANY IMPROVEMENT ARE GENERALLY SHORT-LIVED AS RISING MOTION
FOSTERS ANOTHER PERIOD OF LIGHT RAIN/DRIZZLE.
ENSEMBLES FAVOR GREATER RESTRICTION IMPROVEMENT POTENTIALLY
FRIDAY NIGHT INTO SATURDAY DUE TO INCREASING SUBSIDENCE
EXPERIENCED IN THE REGION (IFR PROBABILITIES LOWER NOTABLY AFTER
00Z). FAVORED A MORE PESSIMISTIC VANTAGE AS STOUT BOUNDARY LAYER
MOISTURE WILL BE DIFFICULT TO ERODE PURELY THROUGH SUBSIDENCE,
RESULTING IN A BKN TO OVC MVFR/IFR STRATOCU LAYER THAT LINGERS
INTO SATURDAY MORNING.
OUTLOOK....
HIGH PRESSURE AND HEIGHT RISES ALOFT SATURDAY WILL OFFER
CIG RISES THROUGH THE DAY, BUT MOISTURE TRAPPED BENEATH THE
POST-FRONTAL INVERSION MAY LIMIT VFR POTENTIAL. HI-RES MODELING
SUGGESTS 50-70% PROBABILITY OF MVFR CIGS LINGERING INTO SATURDAY
EVENING AND EXHIBITING A GRADUAL REDUCTION IN MVFR CIG
LIKELIHOODS THROUGH SUNDAY MORNING FROM THE SOUTHWEST TO THE
NORTHEAST.
CONFIDENCE IS HIGH THAT VFR WILL DEVELOP AREAWIDE BY SUNDAY
AFTERNOON BEFORE THE NEXT WEAK DISTURBANCE CROSSING MONDAY
OFFERS INCREASED RAIN/RESTRICTION PROBABILITIES THAT FAVOR
NORTHWEST PA.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...RACKLEY
AVIATION...FRAZIER
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