Area Forecast Discussion
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958 FXUS61 KPBZ 091137 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 637 AM EST TUE FEB 9 2016 .SYNOPSIS... COLDER WITH SNOW SHOWERS THROUGH WEDNESDAY AS A COLD FRONT PASSES TONIGHT FOLLOWED BY SLOW MOVING LOW PRESSURE. && .NEAR TERM /THROUGH TONIGHT/...
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LATEST RADAR IMAGERY SHOWS AREAL COVERAGE OF LIGHT SNOW EXPANDING. AXIS OF THE UPPER-LEVEL LOW IS DIGGING IN ACROSS WESTERN OHIO...DEEPENING A SECONDARY MID-LEVEL CIRCULATION NEAR THE OHIO RIVER. THE RESULTANT DEFORMATION ZONE GAVE RISE TO A MODERATE SNOW BAND THAT STRETCHED WEST TO EAST FROM WILMINGTON OH TO NEAR CLARKSBURG WV. THIS FORCING IS EXPECTED TO GRADUALLY PIVOT AROUND THE MID-LEVEL LOW...SPREADING LIGHT TO MODERATE SNOW ACROSS OUR SOUTHERN ZONES. THIS SHOULD IMPACT THE REMAINING COMMUTE FOR THE SOUTHERN PORTION OF THE ADVISED AREAS...WITH LESS OF AN IMPACT NEAR THE PITTSBURGH METRO. HI-RES MODELS CONTINUE TO INDICATE A FAIRLY SHARP GRADIENT ALONG THE NORTHERN EDGE OF THE SNOW TODAY. LATEST HRRR RUN HAS COME MORE IN LINE WITH THE WRF ARW/NMM...KEEPING THE HEAVIEST SNOW JUST SOUTH OF PITTSBURGH BUT STILL IMPACTING SOUTHERN ALLEGHENY COUNTY. HAVE ADJUSTED SNOW AMOUNTS ACCORDINGLY BY TIGHTENING THE GRADIENT FROM NEAR PITTSBURGH TO NEAR ZANESVILLE. WHILE THIS MEANS A FURTHER REDUCTION IN THE FORECAST SNOW AMOUNTS ALONG THE NORTHERN EDGE OF THE ADVISORY COUNTIES...OPTED TO STAND PAT WITH THE CURRENT HEADLINES. LOCATIONS SOUTH OF PITTSBURGH AND INTO THE RIDGES SHOULD SEE SEVERAL HOURS OF LIGHT TO MODERATE SNOW THROUGH THE AFTERNOON/EARLY EVENING AS THE LIFT WEAKENS AND DEPARTS. STILL EXPECTING 4 TO 6 INCHES OF ACCUMULATION FROM NEAR THE MASON-DIXON LINE AND SOUTH. SNOW SHOWER COVERAGE SHOULD DIMINISH ACROSS THE LOWLANDS TONIGHT...BUT WILL CONTINUE FOR THE RIDGE COUNTIES AS THE FLOW TURNS TO THE NORTHWEST AND THE DENDRITIC GROWTH ZONE DESCENDS UNDER COLD AIR ADVECTION. TEMPERATURES WILL CONTINUE THEIR DOWNWARD TREND AS HIGHS WILL REMAIN NEAR OR BELOW FREEZING TODAY...AND LOWS WILL DROP TO NEAR NORMAL TONIGHT. TAX
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... H500 TROUGH AXIS SHIFTS EAST EARLY ON WEDNESDAY AS CLOSED LOW OPENS UP. NEXT SHORTWAVE WILL ARRIVE DURING THE DAY WITH AN INCREASE IN COLD ADVECTION. INVERSION HEIGHTS DROP A BIT AS COMPARED TO TODAY AND OVERALL MOISTURE LEVEL IS LOWER...BUT ENOUGH MOISTURE IS PRESENT IN DENDRITIC GROWTH ZONE TO PROMOTE ADDITIONAL SNOW ACCUMULATION OF AN INCH OR TWO...ESPECIALLY IN THE RIDGES. COLD ADVECTION SLOWS WEDNESDAY NIGHT AND MOISTURE BECOMES MORE SHALLOW WITH TIME...WHICH WILL SLOW ACCUMULATION A BIT. ANOTHER INCH OR SO IS POSSIBLE IN THE HIGHER ELEVATIONS...LESS TO THE WEST. H850 THERMAL TROUGH ARRIVES AND CROSSES ON THURSDAY...WHICH WILL HELP TO DIMINISH COVERAGE THROUGH THE DAY. ONLY A FEW SHSN ARE EXPECTED TO LINGER ALONG THE RIDGES AND NORTH OF I-80 BY EVENING...WITH A DRY WINDOW EXPECTED AREAWIDE OVERNIGHT. TEMPERATURES WILL CONTINUE TO DROP FURTHER BELOW NORMAL THROUGH THIS PERIOD. ONLY MINOR CHANGES WERE MADE HERE. CL && .LONG TERM /FRIDAY THROUGH MONDAY/... ANOTHER SHORTWAVE IS EXPECTED ARRIVE ON FRIDAY WITH SCATTERED SNOW SHOWERS...LASTING INTO SATURDAY. KEPT POPS IN THE CHANCE RANGE FOR NOW. THE MAIN STORY HERE WILL BE THE POSSIBLE ARRIVAL OF THE COLDEST AIR OF THE SEASON THUS FAR. H850 TEMPS ARE PROGGED TO FALL TO -25C OR EVEN A BIT COLDER BY 00Z SUNDAY. BELOW ZERO MIN TEMPS ARE A GOOD POSSIBILITY SATURDAY NIGHT...PARTICULARLY IF SKIES CLEAR AND WINDS DECOUPLE. A DRY AND COLD SUNDAY IS EXPECTED AS THE ARCTIC HIGH PRESSURE CROSSES. THIS WILL BE FOLLOWED BY MODERATING TEMPERATURES ON MONDAY AS THE EASTERN U.S. TROUGH LOOSENS ITS GRIP...BUT PRECIPITATION CHANCES WILL RETURN AS WELL WITH THE NEXT SHORTWAVE TROUGH. THE SUPERBLEND GUIDANCE WAS USED AS A BASIS FOR MUCH OF THE LONG TERM FORECAST. CL && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... CONDITIONS CONTINUE TO DETERIORATE THIS MORNING AS SPATIAL COVERAGE OF LIGHT TO MODERATE SNOW EXPANDS. EXPECTING AT LEAST MVFR/IFR RESTRICTIONS THROUGH THE DAY AS SNOW LIFTS NORTHWARD UNDER THE UPPER-LEVEL LOW PRESSURE CENTER. GREATEST IMPACTS SHOULD BE TO THE SOUTHERN TERMINALS OF LBE/MGW/AGC WITH SNOW LASTING INTO THE EVENING. GUIDANCE HINTING AT GRADUAL IMPROVEMENT LATE TONIGHT INTO EARLY WEDNESDAY AS THE AXIS OF THE LOW BEGINS TO SHIFT EAST. STILL...LIGHT SNOW SHOWERS WILL CONTINUE THROUGH WEDNESDAY...SO RESTRICTIONS ARE STILL TO BE EXPECTED. LIGHT SURFACE FLOW WILL GRADUALLY SHIFT TO THE WEST AND INCREASE THROUGH TONIGHT. TAX .OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... RESTRICTIONS ARE EXPECTED THROUGH SATURDAY UNDER COLD UPPER- LEVEL TROUGHING. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR OHZ049- 050-057>059-068-069. PA...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR PAZ021- 029-031-073-075. WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR PAZ074- 076. WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ001>004-012-021-509. WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR WVZ510>514. && $$

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