-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 041052
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
552 AM EST WED MAR 4 2015

.SYNOPSIS...
RAIN WILL TURN TO SNOW TONIGHT...WITH SEVERAL INCHES OF SNOW
EXPECTED INTO NORTHERN WEST VIRGINIA. TEMPERATURES WILL BE
UNSEASONABLY COLD INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 4 PM THIS AFTERNOON/...
QUICK UPDATE AT 545AM TO ACCOUNT FOR SNOW TURNING TO RAIN SLIGHTLY
AHEAD OF SCHEDULE. STILL ANTICIPATE THAT PRECIPITATION SHIELD WILL
TREND SOUTHWARD OVER THE NEXT FEW HOURS...BUT HAVE ADDED MINIMAL
MENTION OF SNOW INTO THE MORNING PORTION OF THE FORECAST AS SOME
OF THE SNOW IS ALREADY MANAGING TO STICK. PREVIOUS DISCUSSION
FOLLOWS.

RAIN CONTINUES ACROSS MUCH OF THE REGION OVERNIGHT WITH MUCH
WARMER TEMPERATURES THAT HAVE RECENTLY BEEN EXPERIENCED.
TEMPERATURES WILL SLOWLY FALL THROUGH THE DAY...ALLOWING FOR A
SLOW TRANSITION IN PRECIPITATION TYPE FROM RAIN TO SNOW NOW THAT A
COLD FRONT HAS MOVED THROUGH THE REGION. ANY SNOWFALL
ACCUMULATIONS DURING THE DAY SHOULD BE MINIMAL DUE TO ABOVE
FREEZING SURFACE TEMPERATURES. HOWEVER...PLENTY OF PRECIPITATION
WILL REMAIN BEHIND THE FRONT...WITH ADDITIONAL RAINFALL RANGING
FROM A TENTH OF AN INCH ALONG THE INTERSTATE 80 CORRIDOR TO THREE
QUARTERS OF AN INCH TOWARDS MORGANTOWN. NO CHANGES WERE MADE TO
THE FLOOD WATCH CURRENTLY IN EFFECT FOR MOST OF THE FORECAST AREA
THROUGH MID AFTERNOON. RAINFALL WILL NOT BE THE ONLY CONTRIBUTING
FACTOR TO FLOODING...AS MELTING SNOW FROM THE SNOWPACK AND ICE
JAMS COULD ALSO PRODUCE LOCAL FLOODING. SEVERAL FLOOD ADVISORIES
HAVE ALREADY BEEN ISSUED...GENERALLY TO THE SOUTH AND EAST OF
PITTSBURGH.

&&

.SHORT TERM /4 PM THIS AFTERNOON THROUGH FRIDAY/...
THE MAIN CHANGEOVER FROM RAIN TO SNOW WILL HAPPEN DURING THE LATE
AFTERNOON INTO EARLY EVENING. ALTHOUGH THE COLDER AIR WILL MOVE IN
BEHIND THE COLD FRONT...THE FRONT ITSELF WILL TAKE ITS TIME MOVING
OUT OF THE REGION...ALLOWING PRECIPITATION TO CONTINUE TONIGHT INTO
THURSDAY. MOST DIFFICULT PART OF THE FORECAST WILL BE DETERMINING
THE WESTERN EDGE OF THE HEAVIEST SNOWFALL...AS A TIGHT GRADIENT IS
EXPECTED. ALL COUNTIES PREVIOUSLY UNDER THE WINTER STORM WATCH
HAVE BEEN PUT INTO A WINTER WEATHER ADVISORY OR WINTER STORM
WARNING...WITH A FEW ADDITIONAL COUNTIES ADDED INTO THE ADVISORY
AS WELL. HAVE GONE SOMEWHAT CONSERVATIVE WITH THE AREA IN THE
WARNING...AND AM CONCERNED THAT HIGHER SNOW TOTALS COULD EDGE A
LITTLE BIT FARTHER NORTH AND WEST. AN ADDITIONAL CONCERN WAS
MODEL SOUNDINGS SHOWING THAT A WARM LAYER ALOFT COULD REMAIN FOR A
FEW HOURS ACROSS THE WV/MD RIDGES...WHICH COULD ALLOW FOR A BRIEF
PERIOD OF FREEZING RAIN DURING THE EVENING HOURS. IF FREEZING RAIN
DEVELOPS...IT WOULD CUT INTO OVERALL SNOWFALL TOTALS...BUT WOULD
PRESENT ITS OWN SET OF PROBLEMS DUE TO ICE ACCUMULATION.

SNOW SHOWERS 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.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM PERIOD LOOKS RELATIVELY QUIET WITH A PROGRESSIVE
PATTERN FEATURING PASSAGE OF A COUPLE OF SHORTWAVE TROUGHS. POPS
WERE FORECAST GENERALLY BELOW CHANCE CLIMO NUMBERS USING GFS
TIMING...BUT LONG TERM CONFIDENCE IS MINIMAL WITH DOUBTS ABOUT
TIMING AND MOISTURE SUPPLY. SEASONALLY COOL TEMPERATURES WERE
FORECAST VIA PERSISTENCE AND MOS.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
IFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE MAJORITY OF THE
DAY AS LOW PRESSURE CROSSES THE GREAT LAKES REGION. A GRADUAL
CHANGEOVER TO SNOW IS EXPECTED FROM NORTH TO SOUTH THROUGH THE
MORNING WITH KMGW THE LAST TO CHANGE OVER JUST BEFORE NOON.  AN
IMPROVEMENT TO LOW END MVFR WILL BE POSSIBLE FROM PIT NORTH BY
AFTERNOON AS THE ASSOCIATED COLD FRONT PUSHES SOUTH.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
WIDESPREAD RESTRICTIONS ARE EXPECTED INTO THURSDAY AS A WAVE OF
LOW PRESSURE MOVES ALONG A COLD FRONT...WITH SNOW MAINLY FROM PIT
SOUTH. RESTRICTIONS ARE POSSIBLE WITH A SUNDAY COLD FRONT.

&&

.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 PERSIST THROUGH THURSDAY. CONFIDENCE IN RAIN AMOUNTS
REMAINS LOW...BUT THE BETTER CHANCE FOR MORE SIGNIFICANT
ACCUMULATION IS EXPECTED TO BE ALONG AND SOUTH OF A ZANESVILLE TO
LATROBE LINE.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FLOOD WATCH THROUGH THIS EVENING FOR MDZ001.
     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR MDZ001.
OH...FLOOD WATCH THROUGH THIS EVENING FOR OHZ049-050-057>059-068-
     069.
     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR OHZ049-050-057>059-068.
     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR OHZ069.
PA...FLOOD WATCH THROUGH THIS EVENING FOR PAZ014-020>023-029-031-
     073>076.
     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR PAZ021-023-029-031-073>075.
     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR PAZ076.
WV...FLOOD WATCH THROUGH THIS EVENING FOR WVZ001>004-012-021>023-
     041.
     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR WVZ001>004.
     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     THURSDAY FOR WVZ012-021>023-041.

&&

$$