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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 121657
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1257 PM EDT WED MAR 12 2014

.SYNOPSIS...
LOW PRESSURE WILL TRACK ACROSS THE REGION THROUGH THIS EVENING
BRINGING RAIN...SNOW...GUSTY WINDS...AND MUCH COLDER TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...

MAIN CHANGE FOR AFTERNOON UPDATE IS TO LOWER SNOW TOTALS
ESPECIALLY ACROSS THE I-80 CORRIDOR WHERE NOW APPEARS DEEP
MOISTURE WILL BE EXITING BEFORE CHANGEOVER TO SNOW WITH 2-4 INCHES
NOW EXPECTED. ELSEWHERE GENERAL 1-3 OUTSIDE OF RIDGES WHERE 2-4
STILL EXPECTED.

HOURLY TEMPERATURES LOOK AS CLOSE AS POSSIBLE TO THE REAL WORLD AS
WHEN SURFACE LOW JUMPS THE RIDGES NEXT 1-2 HOURS COLD AIR AND
STRONG WINDS WILL QUICKLY OVERTAKE THE REGION. CHANGEOVER TIMING
TO SNOW STILL LOOKS REALISTIC. PREVIOUS FOLLOWS...

CHANGES TO GRIDS INCLUDED ANOTHER ATTEMPT TO TIME THE COLD AIR
INTO THE REGION AS WELL AS WIND SHIFT AND STRONGER WINDS. APPEARS
COLD AIR IS SEEPING SOUTH A BIT FASTER THAN PREVIOUS FORECAST SO
SPED UP TEMPERATURE DROP SOMEWHAT AND BROUGHT CHANGEOVER TO SNOW
IN A BIT QUICKER AS WELL. LEFT THE SLIGHT CHANCE FOR A RUMBLE OF
THUNDER BUT THIS SEEMS TO BE A NON ISSUES WITH NO LOW LEVEL
INSTABILITY AVAILABLE. REMAINDER OF FORECAST UNCHANGED.


AS THE SFC LOW PUSHES EAST AND CONTINUES TO BOMB OUT NEAR THE
COAST...COLD AIR WILL QUICKLY MOVE IN DROPPING 850MB TEMPS AROUND 20
DEGREES IN 6 HRS. WHILE THIS QUICK TRANSITION WONT LEND TO MUCH
RESIDENCE TIME OF MIXED PRECIPITATION IN ANY ONE LOCATION...DID KEEP
A MENTION OF BRIEF SLEET ESPECIALLY IN THE N AND W. ONE OF THE ONLY
NOTABLE CHANGES IN THE FORECAST IS THE QUICKER ADVECTION PROGGED BY
THE MODELS. HAVE MODIFIED SFC TEMPS/DEW POINTS TO ACCOUNT FOR THIS
QUICKER SOLN.

STILL EXPECTING THE HEAVIEST SNOW IN THE CWA TO OCCUR NORTH OF I-80.
KEEPING ADVISORIES POSTED FOR ALL ZONES AS THE RAPID FREEZING AND
HIGH WINDS COMBINED WITH ANY SNOWFALL WILL CAUSE TRAVEL PROBLEMS.
TEMPERATURES BOTTOM OUT THURS MORNING...AND COMBINED WITH THE
WIND...WIND CHILL VALUES WILL DROP WELL BELOW ADVISORY CRITERIA FOR
THE ERN 2/3 OF THE CWA. COULDNT JUSTIFY EXTENDING THE WW ADVISORY
FOR WC VALUES ALONE...AS SNOW TAPERS DOWN THURS MORNING...THUS ALSO
INCLUDING A WIND CHILL ADVISORY BEGINNING THURS MORNING.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
STRONG COLD ADVECTION CONTINUES INTO THURSDAY MORNING AS CONSENSUS
850 MB TEMPERATURES PLUNGE TOWARD AND BELOW -20C IN PLACES. BUFKIT
SOUNDINGS CONTINUE TO INDICATE A FAIRLY WELL MIXED BOUNDARY LAYER
WITH FALLING INVERSION HEIGHTS...SO GUSTY UPSLOPE WINDS WILL
LIKELY CONTINUE TO FUEL SNOW SHOWERS AND FLURRIES IN THE RIDGES
INTO THE MORNING EVEN AS DEEP LAYER MOISTURE WILL HAVE LONG
DEPARTED TO THE EAST. EVEN BOUNDARY LAYER MOISTURE WANES VERY
DECIDEDLY THROUGH THE MORNING HOURS...SO UPSLOPE SNOW
SHOWERS/FLURRIES SHOULD END THROUGH THE DAY WITH THE COLUMN LIKELY
BECOMING DRY ENOUGH IN MUCH OF THE AREA FOR SOME SUNSHINE THROUGH
THE DAY. HOWEVER...EVEN WITH THE STRONG MARCH SUN...NORTHWEST FLOW
WILL CONTINUE UNABATED THROUGH THE DAY AND 850 MB TEMPERATURES
WILL FAIL TO REBOUND MUCH. AS A RESULT...TEMPERATURES ACROSS THE
AREA ARE LIKELY TO REMAIN IN THE 20S THROUGH THE DAY...WHICH IS
ROUGHLY 25 DEGREES BELOW NORMAL.

CLEARING SKIES...LIGHTER WINDS...AND SOME SNOW COVER WILL LIKELY
ALLOW FOR THURSDAY NIGHT TO AGAIN DROP OFF FAIRLY RAPIDLY IN
TEMPERATURE. THE EVENTUAL LOWS WILL LIKELY BE MODULATED BY THE
DEGREE OF DECOUPLING...HOWEVER THE MUCH BELOW NORMAL TEMPERATURES
ARE SURE TO CONTINUE AT LEAST UNTIL FRIDAY MORNING.

ZONAL FLOW ALOFT QUICKLY BECOMES SOUTHWESTERLY BY FRIDAY
AFTERNOON. THIS WILL ALLOW FOR 850 MB TEMPERATURES TO RAPIDLY
REBOUND WELL ABOVE 0C. ADDITIONALLY...THE STORM TRACK WILL
PREFERENTIALLY FAVOR THE AREAS TO OUR NORTH. THIS WILL RESULT IN A
WARMER/DRY PERIOD ACROSS THE AREA UNTIL FRIDAY NIGHT.

BY FRIDAY NIGHT AND SATURDAY...THERE IS STRONG MODEL CONSENSUS ON
A WAVE DROPPING THROUGH IN THE NORTHWEST FLOW WHICH SHOULD
REESTABLISH CYCLONIC FLOW OVER OUR REGION AND AGAIN BRING COLDER
AIR BACK INTO THE PICTURE. THE WAVE WILL LIKELY BRING A PERIOD OF
RAIN IN ADVANCE OF THE ARRIVAL OF THE COLD AIR WITH MOISTURE
LIKELY TO WANE BEFORE ANY SIGNIFICANT CHANGEOVER TO SNOW WOULD
OCCUR. FRIES

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
UPPER LEVEL CYCLONIC FLOW CONTINUES TO HOLD COURT OVER THE REGION
FROM THE LATTER HALF OF THE WEEKEND THROUGH THE EARLY PORTION OF
NEXT WEEK. SHORT WAVE DETAILS ARE REALLY LACKING AT THE
MOMENT...HOWEVER THE LARGE SCALE PATTERN IS LIKELY TO FAVOR OVERALL
BELOW NORMAL TEMPERATURES WITH NO SIGNIFICANT INFLUX OF MOISTURE
PARTICULARLY LIKELY TO AFFECT THE AREA THROUGH THE PERIOD. FRIES

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
MVFR TO IFR CONDS WL CONT TDA AS LOW PRES TRACKS ACRS SRN PA. RAIN
WL CHG TO SNW FM NW-SE DURG THE AFTN WITH MVFR TO IFR CONTG.
ALSO...ON THE WRN SIDE OF THE LOW...NNW WND GUSTS ARND 35KT ARE
EXPD INTO THE EVE...CREATING A STG X WND AT PIT. SNW SHOULD TAPER
OFF OVRNGT WITH VFR RTNG BY THU MRNG.

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
RSTRNS ARE PSBL FRI NGT INTO SAT WITH A CROSSING CDFNT...OTRW VFR
CONDS EXPD.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WIND CHILL ADVISORY FROM 1 AM TO NOON EDT THURSDAY FOR MDZ001.
     WINTER WEATHER ADVISORY UNTIL 8 AM EDT THURSDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 1 AM EDT THURSDAY FOR OHZ039>041-
     048>050-057>059-068-069.
     WIND CHILL ADVISORY FROM 1 AM TO NOON EDT THURSDAY FOR
     OHZ039>041-049-050.
PA...WINTER WEATHER ADVISORY UNTIL 1 AM EDT THURSDAY FOR PAZ013-014-
     020>023-029-031-073-075.
     WIND CHILL ADVISORY FROM 1 AM TO NOON EDT THURSDAY FOR
     PAZ007>009-013>016-020>023-029-073>076.
     WINTER WEATHER ADVISORY UNTIL 8 AM EDT THURSDAY FOR PAZ074-076.
     WINTER WEATHER ADVISORY UNTIL 4 AM EDT THURSDAY FOR PAZ007>009-
     015-016.
WV...WINTER WEATHER ADVISORY UNTIL 1 AM EDT THURSDAY FOR WVZ001>004-
     012-021-022.
     WIND CHILL ADVISORY FROM 1 AM TO NOON EDT THURSDAY FOR
     WVZ001>003-023-041.
     WINTER WEATHER ADVISORY UNTIL 8 AM EDT THURSDAY FOR WVZ023-041.

&&

$$