-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 131235
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
835 AM EDT THU MAR 13 2014

.SYNOPSIS...
-- Changed Discussion --
CONTINUED COLD AND BRISK WITH STRAY FLURRIES ENDING THIS MORNING. WARMER
FRIDAY AHEAD OF THE NEXT COLD FRONT APPROACHING FRIDAY NIGHT.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
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HAVE ADDED A FEW FLURRIES ALONG THE PA TURNPIKE TO THE OHIO LINE
AS A COUPLE STREAMERS STILL MOVING DOWN FROM LAKES. WIND CHILLS
STILL BELOW CRITERIA I-80 AND RIDGES AND CLOSE ELSEWHERE. WILL
EVALUATE EACH HOUR AND CANCEL EARLY IF POSSIBLE.

SURFACE HIGH WILL MOVE EAST OF REGION TONIGHT. SHARP DROP OFF IN
TEMPS EARLY THEN STEADY OR RISING AS WARM ADVECTION BEGINS
OVERNIGHT ON BACKSIDE OF HIGH PRESSURE.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
DRY AIR OVER THE REGION TO START THE SHORT TERM PERIOD WITH
INCREASING SOUTHWESTERLY FLOW AND GOOD MIXING SHOULD ALLOW FOR
TEMPERATURES TO REALLY TAKE A RUN NORTHWARD ON FRIDAY. AS
SUCH...THE COLD TEMPERATURES OF TODAY WILL BE BUT A MEMORY AS THE
VAST MAJORITY OF THE AREA EASILY RUNS INTO THE 50S.

ONE DAY OF WARMING WILL BE ABOUT ALL WE CAN MUSTER...HOWEVER...AS
THE NEXT SYSTEM IN THE RETURN OF CYCLONIC FLOW TO THE REGION LOOKS
TO DROP THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY IN THE FORM OF
A COLD FRONT. LIFT AHEAD OF THE FRONT IN THE WARM AIR SHOULD ALLOW
FOR ALL RAIN VIRTUALLY EVERYWHERE AS THE FRONT DROPS THROUGH.
ADDITIONALLY...WHILE LOW LEVEL COLD ADVECTION IS RATHER IMPRESSIVE
BEHIND THE FRONT GOING INTO SATURDAY AND SATURDAY NIGHT...THE
DENDRITIC LAYER NEVER REALLY FALLS OFF TOWARD THE WANING
SATURATION IN THE BOUNDARY LAYER. AS SUCH...MOST LOCATIONS SEEM
LIKELY TO END AS RAIN RATHER THAN ACHIEVE EVEN A BRIEF CHANGEOVER
TO SNOW. LIKEWISE...LOW LEVEL FLOW QUICKLY TURNS WESTERLY THEN
SOUTHWESTERLY ON SATURDAY...WHICH WILL KEEP THE INFLUENCE OF LAKE
MOISTURE FROM REALLY PLAYING MUCH OF A ROLE OVER OUR AREA.

ALL EYES THEN POINT WESTWARD AS A CLIPPER SYSTEM DROPS INTO THE
MID-MISSISSIPPI VALLEY. MODEL SOLUTIONS CONTINUE TO HAVE
SIGNIFICANT DIFFICULTY RESOLVING HOW THIS SYSTEM WILL INTERACT
WITH THE SUBTROPICAL JET STREAM THAT WILL BE POSITIONED OVER THE
SOUTHEAST. REGARDLESS OF THE SOLUTION...AS SOME SORT OF
INTERACTION BETWEEN THE TWO STREAMS TAKES PLACE TO OUR
SOUTHWEST...LOW LEVEL FLOW IS LIKELY TO TURN NORTHERLY AND
NORTHEASTERLY...ALLOWING FOR A STRONG PUSH OF COLD AIR INTO OUR
AREA BEGINNING LATE IN THE WEEKEND. FRIES

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
WHILE THE SYSTEM TO THE SOUTHWEST SEEMS LIKELY TO DEEPEN AS THE
POLAR AND SUBTROPICAL STREAMS INTERACT AND EJECT THE SYSTEM TO THE
NORTHEAST...SIGNIFICANT UNCERTAINTY REMAINS IN WHAT EVENTUAL TRACK
THIS SYSTEM MAY TAKE. THE ECMWF HAS WAFFLED FROM A NORTHERLY TO A
SOUTHERLY TRACK WITH THE LATEST RUN...WHILE THE CANADIAN TRENDED
DECIDEDLY NORTHWARD...AND THE GFS HAS MAINTAINED IN ALMOST EVERY
CYCLE A MORE SUPPRESSED TRACK. GIVEN GFS CONSISTENCY AS WELL AS
NEW 00Z ECMWF AGREEMENT...THE SUPPRESSED TRACK WAS FAVORED. AS
SUCH...POPS REALLY ONLY REACH EVEN CHANCE IN THE SOUTHEASTERN
PORTIONS OF THE FORECAST AREA CENTERED AROUND MONDAY FOR SNOW.
HOWEVER...THE TRACK OF THIS SYSTEM IS STILL VERY UNCERTAIN...SO
ATTENTION SHOULD BE PAID TO FUTURE FORECASTS AS THE EVOLUTION OF
THE INTERACTION BETWEEN THE NORTHERN AND SOUTHERN STREAM AS WELL
AS PHASING IS UNLIKELY TO BE PROPERLY HANDLED AT THIS JUNCTURE BY
ANY MODEL PARTICULARLY WELL. ADDITIONALLY...THE LACK OF
CONSISTENCY IN THE ECMWF SOLUTION IS RATHER TROUBLING AND THE
DIVERGENCE BETWEEN THE LEFTWARD JAUNT OF THE CANADIAN AND
RIGHTWARD JAUNT OF THE ECMWF FLIES IN THE FACE OF ANY MODEL
AGREEMENT. THAT SAID...THE NEW FORECAST REALLY VARIES ONLY
NOMINALLY FROM THE PREVIOUS ONE IN FOCUSING THE CHANCE FOR
PRECIPITATION IN THE SOUTHEAST AS WELL AS ALLOWING FOR A RATHER
QUICK RETURN TO DRY CONDITIONS THEREAFTER.

WHILE MODERATING TEMPERATURES SEEM LIKELY GOING INTO MID-
WEEK...ALREADY INDICATIONS ON THE MODELS ARE THAT THIS PATTERN
SHOULD BE SHORT LIVED WITH A RETURN TO TROUGHING AND COLD
ADVECTION BY THE SECOND HALF OF THE WEEK. FRIES

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
EXPECT VFR CONDITIONS TODAY UNDER CLEARING SKIES. AS THE STRONG
LOW PRESSURE WINDS WILL SLACKEN SOME...BUT SOME GUSTS COULD STILL
OCCUR THROUGH THE EARLY AFTERNOON.

.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 UNTIL NOON EDT TODAY FOR MDZ001.
OH...WIND CHILL ADVISORY UNTIL NOON EDT TODAY FOR OHZ039>041-049-
     050.
PA...WIND CHILL ADVISORY UNTIL NOON EDT TODAY FOR PAZ007>009-
     013>016-020>023-029-073>076.
WV...WIND CHILL ADVISORY UNTIL NOON EDT TODAY FOR WVZ001>003-023-
     041.

&&

$$