-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 032028
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
328 PM 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 /THROUGH WEDNESDAY/...
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DRY AIR HAS BEEN FULLY ERODED AND RAIN IS OVERSPREADING THE AREA
QUICKLY. WARM SOUTHERLY FLOW HAS BROUGHT TEMPERATURES UP INTO AT
LEAST THE MID 30S NEAR PITTSBURGH...UPPER 30S OR LOW 40S SOUTH OF
PITTSBURGH. THE WINTER WEATHER ADVISORY FOR THESE AREAS HAVE BEEN
ALLOWED TO EXPIRE.

NORTH OF ALLEGHENY COUNTY TEMPERATURES HAVE STILL HELD IN THE
UPPER 20S AND WILL FOR THE NEXT FEW HOURS. AS THE RAIN HAS MOVED
INTO THESE SUB-FREEZING AREAS...REPORTS OF FREEZING RAIN HAVE BEGUN TO
COME IN. WINTER WEATHER ADVISORIES WILL CARRY ON FOR OUR NORTHERN
9 COUNTIES THROUGH 00Z...BUT WITH RAPID WARMING...WOULD NOT BE
SURPRISED TO DROP THEM EARLY.

TONIGHT THE FOCUS OF THE RAIN WILL TRANSITION TO THE TRAILING
BAROCLINIC ZONE THAT STRETCHES BACK THROUGH THE OHIO VALLEY.
MOISTURE WILL BEGIN TO STREAM IN FROM THE GULF OF MEXICO WITH TONIGHT
AS THE STRONG LOW-LEVEL JET MOVES ALONG THE FRONT. THIS WILL SHIFT
THE FOCUS OF THE RAIN TO OUR SOUTHEASTERN ZONES...WHILE
DISSIPATING PRECIPITATION ACROSS THE NORTH. CURRENT AREAL FLOOD
WATCH WILL REMAIN...BUT WITH FURTHER SHIFT SOUTH...THE NORTHERN
EXTENT OF THE WATCH MAY BE TRIMMED.

COLD AIR WILL MOVE IN WEDS NEAR DAY BREAK AND SURFACE TEMPS WILL
FOLLOW A NON-DIURNAL TREND. A TRANSITION TO SNOW WILL OCCUR ALONG
THE WESTERN EDGE OF THE PRECIPITATION WITH THE RAIN/SNOW LINE
HOLDING NEAR PITTSBURGH FOR SEVERAL HOURS DURING THE DAY AS
TEMPERATURES HOVER NEAR FREEZING. ANY SNOW THAT FALLS THROUGH THE
DAY WEDS SHOULD BE FAIRLY INEFFICIENT WITH SNOW RATIOS BELOW 10:1.
LITTLE ACCUMULATION IS EXPECTED THROUGH WEDS EVENING.
TAX
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&&

.SHORT TERM /WEDNESDAY NIGHT/...
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WINTER STORM WATCH HAS BEEN EXPANDED NORTH TO INCLUDE ANOTHER TIER
OF COUNTIES AS 12Z MODELS CONTINUE TO WAVER IN HOW FAR NORTH
DEEPER MOISTURE AND LIFT WILL EXPAND WEDNESDAY NIGHT INTO EARLY
THURSDAY. PRECIPITATION WILL BE ALL SNOW BY SUNSET WEDNESDAY
EXCEPT FOR A MIX IN THE FAR SOUTHEAST RIDGES FOR AN HOUR OR TWO
BEFORE DEEPER COLD AIR ARRIVES. THEN PERIODS OF SNOW WILL BE
ACROSS MUCH OF THE REGION OUTSIDE OF THE I-80 CORRIDOR WEDNESDAY
NIGHT INTO EARLY THURSDAY AS A WAVE MOVES ALONG THE COLD FRONT
PUSHING MOISTURE BACK OVER THE VERY COLD AIR MASS MOVING INTO THE
REGION. BEST MOISTURE AND LIFT STILL LOOKS TO BE ACROSS THE FAR
SOUTH WHERE HIGHEST AMOUNTS EXPECTED ALONG THE MASON DIXON LINE
INTO THE RIDGES OF FAYETTE...AND PRESTON...GARRETT AND TUCKER.
NORTH OF THIS WILL BE A CLOSE CALL WITH HOW FAR NORTH INTO THE
DEEPER COLD AIR MOISTURE CAN BE THROWN...AND BETTER SNOW RATIOS
WOULD BE EXPECTED. NORTH TOWARD I-80 LIGHTER AMOUNTS UNDER
ADVISORY CRITERIA EXPECTED.

SNOW WILL DIMINISH THROUGH THURSDAY AFTERNOON WITH ARCTIC HIGH
PRESSURE CLEARING OUT SKIES. WITH LIGHT WINDS TEMPERATURES
EXPECTED TO CRASH NEAR OR BELOW ZERO WITH FRESH SNOW COVER.

SUNSHINE BUT CONTINUED COLD FRIDAY WITH TEMPERATURES 15 TO 20
DEGREES BELOW SEASONAL AVERAGES.
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&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
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 /20Z TUESDAY THROUGH SUNDAY/...
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ADVANCING WARM FRONT SHOULD BRING IFR A MIX OF SNOW...FREEZING
RAIN AND RAIN TO KFKL AND KDUJ THROUGH 21Z OR SO...WITH SPOTTY
MIXED PRECIP TO PLAIN RAIN THIS AFTERNOON ELSEWHERE. IFR IN RAIN
OVERNIGHT FOR ALL PORTS OVERNIGHT...THEN IFR CONTINUES WEDNESDAY AS COLD
FRONT PUSHES SOUTH WITH RAIN MIXING OVER TO SNOW NORTH TO SOUTH.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
WIDESPREAD RESTRICTIONS ARE EXPECTED INTO THURSDAY AS LOW PRESSURE
MOVES ALONG A COLD FRONT. GENERAL VFR UNTIL A COLD FRONT BRINGS
POSSIBLE RESTRICTIONS SUNDAY.
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&&

.HYDROLOGY...
THE COMBINATION OF SNOW MELT AND DEVELOPING RAIN IS EXPECTED TO CAUSE
SIGNIFICANT RISES ON THE CHEAT... MONONGAHELA AND YOUGHIOGHENY
RIVER BASINS. THESE RISES WILL AID IN MOVING ICE INTO AREAS WHERE
ICE JAMS ARE KNOWN TO DEVELOP. THE RISES WILL MOST LIKELY BEGIN
WEDNESDAY MORNING THROUGH THURSDAY AFTERNOON. UNCERTAINTY REMAINS
A FACTOR ON THE AMOUNT OF PRECIPITATION AND WHERE THE AXIS OF
HEAVIEST RAIN WILL FALL.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
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MD...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY
     EVENING FOR MDZ001.
     WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     AFTERNOON FOR MDZ001.
OH...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY
     EVENING FOR OHZ049-050-057>059-068-069.
     WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     AFTERNOON FOR OHZ057>059-068-069.
PA...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY
     EVENING FOR PAZ014-020>023-029-031-073>076.
     WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     AFTERNOON FOR PAZ021-023-029-031-073>076.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     PAZ007>009-013>016-022-023.
WV...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY
     EVENING FOR WVZ001>004-012-021>023-041.
     WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     AFTERNOON FOR WVZ002>004-012-021>023-041.
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&&

$$