Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 031438 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 938 AM 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 /UNTIL 6 PM THIS EVENING/... LATEST RADAR IMAGERY SHOWING WEAK ECHOES ENCAPSULATING THE AREA...BUT COPIOUS DRY AIR IN PLACE IS KEEPING MOST PRECIPITATION AT BAY. 12Z SOUNDING SHOWING NEARLY A 50C DEWPOINT SPREAD AT 850MB. UNTIL WE ERODE THIS COMPLETELY...VIRGA WILL BE PRESENT. THE DRY AIR LOOKS TO HOLD INTO THE SOUTHEAST RIDGES THE LONGEST AS 925MB FLOW REMAINS FROM THE SOUTHEAST. THIS WILL KEEP MOST AREAS SOUTH AND EAST OF PITTSBURGH DRY IN DOWNSLOPING FLOW UNTIL THE AFTERNOON WHEN THE FLOW VEERS TO THE SOUTH. HAVE RE-CONFIGURED THE WINTER WEATHER ADVISORIES WITH THE LARGEST CHANGES INCLUDING CANCELLING THE ADVISORY IN THE RIDGES AND SPEEDING UP THE START TIME EVERYWHERE ELSE. STILL...WITH ALL THE DRY AIR IN PLACE AND THE LACK OF UPSTREAM RADAR ACTIVITY...THE PROBABILITY OF A WIDESPREAD ICING EVENT HAS DROPPED. ONCE THE LOW-LEVEL FLOW VEERS TO THE SOUTH MUCH WARMER AIR SHOULD STREAM IN AND ALLOW ANY REMAINING ICING THREAT TO END. THIS WILL HAPPEN SOUTH TO NORTH THROUGH THE AFTERNOON/EVENING. HAVE TAILORED THE ADVISORIES TO FOLLOW THIS TRANSITION. TAX && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... WITH ONGOING WARM AIR AND MOISTURE ADVECTION INTO THE EVENING...RAIN WILL CONTINUE FALL AREA WIDE AND TEMPERATURES WILL CONTINUE TO INCREASE UNTIL THE ASSOCIATED COLD FRONT SWEEPS ACROSS THE REGION STARTING SHORTLY AFTER MIDNIGHT. RAIN WILL REMAIN FAIRLY STEADY WITH THE GREATEST AMOUNTS FOCUSED WHERE MID- LEVEL CONVERGENCE IS GREATEST...ALONG THE I80 CORRIDOR EARLY IN THE EVENING AND SHIFTING SOUTH OF THE PA/WV BORDER BY WEDNESDAY MORNING. WITH STRONG MID-LEVEL MOISTURE TRANSPORT INTO THE AREA AND UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF A +170KT JET...PORTIONS OF OUR FORECAST AREA COULD RECEIVE 1-1.5" OF LIQUID THROUGH LATE WEDNESDAY. THIS...COMBINED WITH THE POTENTIAL FOR SNOW MELT AND ICE ON LOCAL CREEKS AND STREAMS...COULD CAUSE HIGH WATER ISSUES FOR AREAS MAINLY SOUTH OF PITTSBURGH. AN AREAL FLOOD WATCH HAS BEEN ISSUED. COLDER AIR WILL BEGIN TO FILTER IN WEDS AS THE UPPER TROF APPROACHES FROM THE WEST. EXPECTING TEMPERATURES TO HOLD PRETTY STEADY THROUGH THE DAY...WHICH KEEPS THE RAIN/SNOW LINE NEAR PITTSBURGH THROUGH THE AFTERNOON. BY LATE EVENING TEMPERATURES WILL HAVE FALLEN ENOUGH TO TRANSITION RAIN TO SNOW FOR ALL LOCATIONS. AGAIN THERE ARE QUESTIONS SURROUNDING HOW MUCH MOISTURE STAYS IN OUR FORECAST AREA THROUGH THURS MORNING AS THE GULF OF MEXICO MOISTURE FEED KICKS IN AND THE UPPER LEVEL TROF BEGINS TO KICK THE BOUNDARY OFF TO OUR EAST. POTENTIAL FOR ACCUMULATING SNOW EXISTS...MAINLY SOUTH AND EAST OF PITTSBURGH WHERE THE DEEPEST MOISTURE HOLDS. CONFIDENCE IN SNOW TOTALS AT THIS POINT IS FAIRLY LOW...AND WILL LIKELY CHANGE AS WE MOVE CLOSER TO MID-WEEK. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... 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 /15Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE MORNING UNDER HIGH PRESSURE. AN ADVANCING WARM FRONT SHOULD BRING A MIX OF SNOW...FREEZING RAIN AND RAIN AT THE ONSET...LATE MORNING INTO THE AFTERNOON...WITH AN EVENTUAL CHANGEOVER TO RAIN AT ALL SITES BY LATE IN THE DAY. CONDITIONS SHOULD DETERIORATE TO MVFR WHEN PRECIP BEGINS...AND EVENTUALLY LOWER TO IFR BY THE LATTER PART OF THE FORECAST PERIOD. .OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... WIDESPREAD RESTRICTIONS ARE EXPECTED THROUGH WEDNESDAY NIGHT AS A COLD FRONT SLOWLY CROSSES THE REGION. A PERIOD OF LOW LEVEL WIND SHEAR IS POSSIBLE TUESDAY EVENING. && .HYDROLOGY... AN INCREASE IN FLOW AND STAGE IS EXPECTED TO CAUSE ICE MOVEMENT STARTING TUESDAY...BEGINNING ON THE SOUTHERNMOST RIVER BASINS. THE COMBINATION OF SNOW MELT AND DEVELOPING RAIN IS EXPECTED TO MOST AFFECT THE MONONGAHELA AND YOUGHIOGHENY BASINS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY EVENING FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR OHZ039>041-048>050-057>059-068. FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY EVENING FOR OHZ049-050-057>059-068-069. PA...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ020-029. FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY EVENING FOR PAZ014-020>023-029-031-073>076. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ007>009-013>016-022-023. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ021-073-074. WV...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR WVZ001>003. FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY EVENING FOR WVZ001>004-012-021>023-041. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.