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Area Forecast Discussion
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000
FXUS61 KPBZ 031035
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
535 AM EST TUE MAR 3 2015

.SYNOPSIS...
LOW PRESSURE CROSSING THE GREAT LAKES WILL SPREAD RAIN OVER THE
UPPER OHIO VALLEY REGION TODAY. PRECIPITATION MAY BEGIN AS
FREEZING RAIN OR A WINTRY MIX...AND WILL END BY TURNING BACK TO
SNOW ON WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE CENTERED OVER THE FORECAST AREA WILL TRANSITION EAST
TODAY AS A DEVELOPING AREA OF LOW PRESSURE ACROSS THE CENTRAL
PLAINS QUICKLY MOVES NORTHEAST...CENTERED OVER THE GREAT LAKES BY
EARLY THIS EVENING. MOISTURE AND TEMPERATURES ALOFT WILL CONTINUE
TO INCREASE SUBSTANTIALLY THROUGH THE MORNING AND AFTERNOON UNDER
STRONG SOUTHWESTERLY FLOW...AND WITH TEMPERATURES STILL BELOW
FREEZING ACROSS MUCH OF THE REGION...CONDITIONS CONTINUE TO LOOK
IDEAL FOR A BRIEF PERIOD OF FREEZING RAIN LATE THIS MORNING
AND THIS AFTERNOON AT MOST LOCATIONS BEFORE CHANGING OVER
COMPLETELY TO RAIN. MAIN CHANGES TO THE ONGOING FORECAST IN THE
NEAR TERM WERE TO PUSH BACK TIMING OF PRECIPITATION SLIGHTLY AS
THERE IS A SUBSTANTIAL DRY LAYER IN THE LOWER LEVELS TO OVERCOME
BEFORE PRECIPITATION BREAKS OUT...AND A SLIGHT INCREASE TO HOURLY
TEMPERATURES BASED ON LATEST TRENDS...WHICH HAVE BEEN A FASTER TO
WARM UP THAN PREVIOUSLY EXPECTED SO FAR THIS MORNING. IF THIS
TREND CONTINUES....AREAS FURTHEST SOUTH AND UNDER CURRENT WINTER
WEATHER ADVISORIES MAY SEE A VERY BRIEF PERIOD OF FREEZING RAIN OR
POTENTIALLY NO FREEZING RAIN AT ALL...BUT IT IS TOO EARLY TO KNOW
JUST YET. THEREFORE HAVE HELD OFF ADJUSTING THE CURRENT ADVISORY
FOR NOW.

AS MENTIONED PREVIOUSLY...THE NORTHEASTERN PORTIONS OF THE
FORECAST AREA LOOK LIKELY TO SEE THE LONGEST PERIOD OF ICING
TODAY...NOT CHANGING OVER TO RAIN UNTIL LATE AFTERNOON/EARLY EVENING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...

WITH ONGOING WARM AIR AND MOISTURE ADVECTION INTO THE
EVENING...RAIN WILL CONTINUE FALL AREA WIDE AND TEMPERATURES WILL
CONTINUE TO INCREASE UNTIL THE ASSOCIATED COLD FRONT SWEEPS
ACROSS THE REGION STARTING SHORTLY AFTER MIDNIGHT. RAIN WILL
REMAIN FAIRLY STEADY WITH THE GREATEST AMOUNTS FOCUSED WHERE MID-
LEVEL CONVERGENCE IS GREATEST...ALONG THE I80 CORRIDOR EARLY IN
THE EVENING AND SHIFTING SOUTH OF THE PA/WV BORDER BY WEDNESDAY
MORNING.
WITH STRONG MID-LEVEL MOISTURE TRANSPORT INTO THE AREA AND UPPER
LEVEL DIVERGENCE ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF A
+170KT JET...PORTIONS OF OUR FORECAST AREA COULD RECEIVE 1-1.5" OF
LIQUID THROUGH LATE WEDNESDAY. THIS...COMBINED WITH THE POTENTIAL
FOR SNOW MELT AND ICE ON LOCAL CREEKS AND STREAMS...COULD CAUSE
HIGH WATER ISSUES FOR AREAS MAINLY SOUTH OF PITTSBURGH. AN AREAL
FLOOD WATCH HAS BEEN ISSUED.

COLDER AIR WILL BEGIN TO FILTER IN WEDS AS THE UPPER TROF APPROACHES 
FROM THE WEST. EXPECTING TEMPERATURES TO HOLD PRETTY STEADY THROUGH 
THE DAY...WHICH KEEPS THE RAIN/SNOW LINE NEAR PITTSBURGH THROUGH THE 
AFTERNOON. BY LATE EVENING TEMPERATURES WILL HAVE FALLEN ENOUGH TO 
TRANSITION RAIN TO SNOW FOR ALL LOCATIONS. AGAIN THERE ARE QUESTIONS 
SURROUNDING HOW MUCH MOISTURE STAYS IN OUR FORECAST AREA THROUGH 
THURS MORNING AS THE GULF OF MEXICO MOISTURE FEED KICKS IN AND THE 
UPPER LEVEL TROF BEGINS TO KICK THE BOUNDARY OFF TO OUR EAST. 
POTENTIAL FOR ACCUMULATING SNOW EXISTS...MAINLY SOUTH AND EAST OF 
PITTSBURGH WHERE THE DEEPEST MOISTURE HOLDS. CONFIDENCE IN SNOW 
TOTALS AT THIS POINT IS FAIRLY LOW...AND WILL LIKELY CHANGE AS WE 
MOVE CLOSER TO MID-WEEK.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
OVERALL...THE LONG TERM PERIOD LOOKS QUIET WITH THE PASSAGE OF A
COUPLE OF WEAK FRONTS SATURDAY NIGHT AND THEN AGAIN LATE MONDAY.
AT THIS TIME...MODELS ARE SHOWING LITTLE MOISTURE ACCOMPANYING
EITHER OF THESE SYSTEMS. A SLOW MODERATION IN TEMPS IS EXPECTED
THROUGH THE ENTIRE PERIOD.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE MORNING UNDER
HIGH PRESSURE. AN ADVANCING WARM FRONT SHOULD BRING A MIX OF
SNOW...FREEZING RAIN AND RAIN AT THE ONSET...LATE MORNING INTO
THE AFTERNOON...WITH AN EVENTUAL CHANGEOVER TO RAIN AT ALL SITES
BY LATE IN THE DAY. CONDITIONS SHOULD DETERIORATE TO MVFR WHEN
PRECIP BEGINS...AND EVENTUALLY LOWER TO IFR BY THE LATTER PART OF
THE FORECAST PERIOD.

.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... 
WIDESPREAD RESTRICTIONS ARE EXPECTED THROUGH WEDNESDAY NIGHT AS A
COLD FRONT SLOWLY CROSSES THE REGION. A PERIOD OF LOW LEVEL WIND
SHEAR IS POSSIBLE TUESDAY EVENING.

&&

.HYDROLOGY...
AN INCREASE IN FLOW AND STAGE IS EXPECTED TO CAUSE ICE MOVEMENT
STARTING TUESDAY...BEGINNING ON THE SOUTHERNMOST RIVER BASINS. THE
COMBINATION OF SNOW MELT AND DEVELOPING RAIN IS EXPECTED TO MOST
AFFECT THE MONONGAHELA AND YOUGHIOGHENY BASINS.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 2 PM EST 
     THIS AFTERNOON FOR MDZ001.
     FLOOD WATCH FROM THIS EVENING THROUGH WEDNESDAY EVENING FOR 
     MDZ001.
OH...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 2 PM EST 
     THIS AFTERNOON FOR OHZ039>041-048>050-057>059-068.
     FLOOD WATCH FROM THIS EVENING THROUGH WEDNESDAY EVENING FOR 
     OHZ049-050-057>059-068-069.
PA...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 2 PM EST 
     THIS AFTERNOON FOR PAZ029-075-076.
     FLOOD WATCH FROM THIS EVENING THROUGH WEDNESDAY EVENING FOR 
     PAZ014-020>023-029-031-073>076.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 PM EST THIS 
     EVENING FOR PAZ007-013-014-020>023-073-074.
     WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM EST 
     THIS EVENING FOR PAZ008-009-015-016.
WV...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 2 PM EST 
     THIS AFTERNOON FOR WVZ001>003-023-041.
     FLOOD WATCH FROM THIS EVENING THROUGH WEDNESDAY EVENING FOR 
     WVZ001>004-012-021>023-041.

&&

$$






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