Area Forecast Discussion
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000 FXUS61 KPBZ 041427 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 927 AM EST WED MAR 4 2015 .SYNOPSIS... MIXED PRECIPITATION WILL TURN TO SNOW ACROSS THE ENTIRE REGION THIS EVENING...WITH SEVERAL INCHES OF SNOW EXPECTED INTO NORTHERN WEST VIRGINIA. TEMPERATURES WILL BE UNSEASONABLY COLD INTO THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... BULK OF HEAVIER PRECIPITATION NOW HEADING INTO THE SOUTHEAST RIDGES AS COLDER AIR ABOVE THE SURFACE PUSHES SOUTHEAST. EXPECT RAIN ALONG I-70 TO MIX OVER TO SNOW OR A BIT OF SLEET BEFORE DIMINISHING FOR A TIME. BOUNDARY INTO CENTRAL OHIO WITH LEADING EDGE OF MUCH COLDER AIR WILL SAG SOUTH THIS AFTERNOON AS SURFACE WAVE WITH SHORTWAVE ALOFT MOVES NORTHEAST ALONG BOUNDARY. SNOW WILL REDEVELOP SOUTHWEST TO NORTHEAST ACROSS AREAS FROM PITTSBURGH SOUTH TOWARD SUNSET AND CONTINUE INTO EARLY THURSDAY. STILL APPEARS BEST LIFT AND QPF WILL BE ACROSS THE FAR SOUTH WHERE WARNING IS IN PLACE. NORTH OF THIS REGION MAY BE A SHARPER CUTOFF TO SNOW AND AMOUNTS IN THE NORTHERN SECTIONS OF ADVISORY AREA MAY BE LOWERED A BIT LATER TODAY DEPENDING ON INCOMING DATA. SNOW WILL DIMINISH THURSDAY MORNING WITH COLD HIGH PRESSURE BUILDING IN THURSDAY AFTERNOON. HEADLINES UNCHANGED. FLOOD PROBLEMS STILL ONGOING INTO THE AFTERNOON BEFORE COLDER AIR BEGINS TO SLOW RUNOFF AND ICE MOVEMENT LATE DAY. && .SHORT TERM /THURSDAY NIGHT 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 /14Z 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 UNTIL 7 PM EST THIS EVENING FOR MDZ001. WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST THURSDAY FOR MDZ001. OH...FLOOD WATCH UNTIL 7 PM EST 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 UNTIL 7 PM EST 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 UNTIL 7 PM EST 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. && $$

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