Area Forecast Discussion
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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/... 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 && .SHORT TERM /WEDNESDAY NIGHT/... 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. && .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/... 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. && .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... 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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