Area Forecast Discussion
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393
FXUS61 KPBZ 110814
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
314 AM EST THU FEB 11 2016

.SYNOPSIS...
SNOW SHOWERS WILL GRADUALLY DIMINISH THURSDAY. TEMPERATURES WILL
CONTINUE TO FALL THROUGH THE WEEK WITH BITTER COLD TO START THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN AXIS OF LOW LEVEL DEFORMATION CONTINUES TO SLOWLY EDGE
SOUTHEASTWARD INTO THE NORTHERN REACHES OF THE AREA EARLY THIS
MORNING. GIVEN THAT SURFACE TEMPERATURES ARE IN THE DENDRITIC
GROWTH THERMAL LAYER AND SURFACE-BASED INSTABILITY IS
PRESENT...THIS AXIS OF DEFORMATION IS SUMMARILY CO-LOCATED WITH A
BAND OF SNOW SQUALLS THAT HAS PLAGUED THE AREA JUST SOUTH OF I-80
TOWARD THE TURNPIKE VIRTUALLY ALL NIGHT. AS THE MORNING
ENSUES...LOW LEVEL CONVERGENCE IN THIS LAYER SHOULD START TO
SUBSIDE...AS FLOW TURNS MORE UNI-DIRECTIONALLY FROM THE
NORTHWEST...WHICH SHOULD ALLOW FOR FAR LESS DOMINANT BANDING ALONG
THIS AXIS...THUS ALLOWING FOR THE SQUALLS TO DIMINISH.
HOWEVER...IN THE INTERIM...A FEW MORE INCHES OF LOCAL ACCUMULATION
WILL BE POSSIBLE...ESPECIALLY ALONG HIGHWAY 422.

ELSEWHERE...UNSTABLE NORTHWESTERLY FLOW WILL BEGIN TO BE OVERCOME
BY DRY CANADIAN AIR ADVECTING IN FROM THE NORTHWEST. THE ONLY
PLACE WHERE THIS MAY NOT ENTIRELY BE THE CASE IS IN FOREST AND
VENANGO COUNTIES. HIGH RESOLUTION GUIDANCE SUGGESTS BANDING FROM
LAKE HURON WILL TREND SOUTHWARD LATE THIS MORNING. THIS WOULD
ALLOW FOR A MULTI-LAKE FETCH TO BRING SNOW SHOWERS FROM LAKE
HURON...ACROSS LAKE ERIE...AND INTO THE FAR NORTHEASTERN REACHES
OF THE CWA. THUS POPS AND THE WINTER WEATHER ADVISORY WILL LIKELY
BE MAINTAINED HERE TO ASCERTAIN WHETHER THIS DEVELOPMENT DOES
OCCUR.

IN THE RIDGES...VISIBILITIES HAVE CONTINUED TO GENERALLY BE
BETWEEN 1 AND 2 MILES THROUGH THE NIGHT. A PERIOD OF A ENHANCED
SNOW SHOWER ACTIVITY WILL BE LIKELY AS FLOW TURNS TO THE
NORTHWEST...HOWEVER WEAKENING SATURATION WILL MEAN LESS EFFICIENT
SNOW GENERATION BY AFTERNOON. THUS A FEW MORE INCHES WILL BE
POSSIBLE IN THE RIDGES...HOWEVER TRENDS BY AFTERNOON SHOULD ALLOW
FOR SNOW SHOWER ACTIVITY TO TAPER OFF.

ELSEWHERE...SCATTERED SNOW SHOWERS WILL BE PRESENT...HOWEVER
ACCUMULATIONS SHOULD BE LIGHT/LOCAL AS DRIER AIR MOVES INTO THE
AREA. IN FACT...GOING INTO THE NIGHTTIME TONIGHT...LOW LEVEL FLOW
STARTS TO WEAKEN CONSIDERABLY AND TURN A BIT TO THE SOUTHWEST.
THIS WILL LIKELY ERADICATE BOUNDARY LAYER RH VALUES...AND ALLOW
FOR DECENT TEMPERATURE FALLS. THEY WILL LIKELY BE TEMPERED BY
MORNING AS MID AND HIGH CLOUDS INCREASE...HOWEVER SINGLE DIGITS
WILL LIKELY STILL BE COMMON WITH WIND CHILLS INCREMENTALLY BELOW
ZERO. FRIES

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
COLDER AIR WILL SURGE SOUTH LATER FRIDAY AS ARCTIC VORTEX DROPS
SOUTH. FRONT WILL CROSS REGION LATER FRIDAY WITH A ROUND OF SNOW
SHOWERS INTO FRIDAY NIGHT. BIGGER STORY WILL BE WIND CHILLS LATER
FRIDAY NIGHT THROUGH SATURDAY 15 TO POSSIBLY 25 BELOW ZERO AS
WINDS REMAIN UP AND TEMPERATURES WILL BE IN THE SINGLE DIGITS.
HEADLINES FOR WIND CHILLS WILL LIKELY BE NECESSARY.

SKIES SHOULD BEGIN TO CLEAR OUT SATURDAY NIGHT AS HIGH PRESSURE
BUILDS INTO THE REGION. ALTHOUGH IT IS EARLY TO SORT OUT EFFECTS
OF FRESH SNOWPACK AND JUST HOW MUCH RADIATIONAL COOLING WILL OCCUR
DUE TO CLEARING SKIES...MODELS REMAIN IN GOOD AGREEMENT THAT
SATURDAY NIGHT WILL BE THE COLDEST NIGHT OF THE WINTER WITH
TEMPERATURES IN MANY LOCATIONS BELOW 0F.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/... SUNDAY SHOULD REMAIN DRY
BEFORE THE NEXT SYSTEM MOVES IN BETWEEN SUNDAY NIGHT AND TUESDAY.
MODELS ARE NOT IN AS GOOD AGREEMENT WITH THIS SYSTEM TODAY AS THEY
WERE YESTERDAY...WITH SOME MODEL GUIDANCE NOW BRINGING IN THE
SYSTEM FROM THE SOUTHWEST INSTEAD OF THE WEST- NORTHWEST...WHICH
WOULD AFFECT BOTH COVERAGE AND TIMING OF ANY PRECIPITATION. WINDS
MAY BE FAVORABLE FOR SOME LAKE EFFECT SNOW SHOWERS BEHIND THE
SYSTEM...WITH A WEAK SYSTEM APPROACHING BY WEDNESDAY. WHILE SUNDAY
AND SUNDAY NIGHT WILL ALSO BE COLD...TEMPERATURES SHOULD BEGIN TO
APPROACH NORMAL VALUES AGAIN FOR THE WORK WEEK.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
SNOW SQUALLS WILL LIKELY REMAIN BETWEEN KBVI AND KFKL THROUGH THE
MORNING BEFORE DISSIPATING. LOCAL SNOW SHOWERS WILL BE POSSIBLE AT
MOST SITES...HOWEVER NO HEAVIER SNOW SHOWERS SHOULD AFFECT ANY
SITE. CIGS WILL SLOWLY IMPROVE THROUGH THE DAY...WITH VFR
CONDITIONS LIKELY AT MOST SITES BY TONIGHT

.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
OCCASIONAL RESTRICTIONS ARE EXPECTED THROUGH THE PERIOD UNDER
COLD UPPER-LEVEL TROUGHING. WHILE THURSDAY NIGHT AND SUNDAY
SHOULD BE GENERALLY DRY...SCATTERED TO WIDESPREAD SNOW SHOWERS ARE
EXPECTED FRIDAY...SATURDAY...AND MONDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR PAZ013-
     014-016-022-023.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     PAZ007>009-015-074-076.
WV...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     WVZ510>514.

&&

$$



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