Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 311055 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 555 AM EST SAT JAN 31 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN THROUGH SATURDAY. LOW PRESSURE WILL BRING WINTRY WEATHER SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
STRATOCU DECK CONTINUES TO ERODE SLOWLY...WITH ONLY THE FAR NORTHEASTERN CWA STILL UNDER THEIR INFLUENCE. THESE WILL CONTINUE TO DISSIPATE...LEAVING MOSTLY CLEAR SKIES AND VERY COLD TEMPERATURES. CONTINUED MINOR PUFF OF WIND HAS KEPT TEMPS FROM REALLY BOTTOMING OUT SO FAR...BUT STILL EXPECT SOME BELOW ZERO VALUES TO BE REALIZED THIS MORNING. HIGH PRESSURE WILL KEEP CWA DRY TODAY. WEAK WARM FRONTAL PASSAGE WILL ALLOW FOR SOME CU/SC CLOUDS LATER THIS MORNING AND THIS AFTERNOON...WITH WARMER H925/H850 AIR ARRIVING ON THE HEELS OF W/WNW WINDS JUST OFF THE SURFACE. LOWER CLOUDS WILL MOVE OFF LATER IN THE DAY...TO BE REPLACED BY INCREASING MID/HI CLOUDS AHEAD OF OUR WELL-ADVERTISED SUNDAY STORM. TONIGHT...FRONTAL BOUNDARY BRIDGING FROM WEAK LOW DROPPING ACROSS EASTERN GREAT LAKES...TO THE MORE SIGNIFICANT SURFACE SYSTEM MOVING INTO MISSOURI... DROPS TOWARD THE NORTHERN CWA. AS THIS OCCURS...MOISTURE BEGINS TO STREAK IN FROM THE WEST ESPECIALLY AFTER 06Z. BEGINNINGS OF DEEP LIFT DRIVEN VIA ISENTROPIC ASCENT AND RRQ OF H250 JET TO THE NORTH WILL START TO SPREAD SNOW ACROSS THE CWA. SLOWED POPS SLIGHTLY FROM PREVIOUS FORECAST BUT STILL BRING LIKELY POPS TO PIT/HLG BY 12Z. SNOW COULD START EARLY ENOUGH TO GET A FRESH INCH ON THE GROUND NEAR ZZV BY 12Z...WITH LESSER AMOUNTS TO THE NORTH AND EAST. TEMPERATURES MODIFIED SLIGHTLY FROM PREVIOUS FORECAST...MAINLY BY BLENDING IN NAM/MET. CL
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY THROUGH MONDAY/... PRECIPITATION WILL START OVERSPREADING THE AREA WEST TO EAST ACROSS THE SFC COLD FRONT SUNDAY AHEAD OF THE VIGOROUS LOW MOVING OUT OF THE PLAINS. SNOW WILL BE THE PRIMARY PRECIPITATION TYPE AS THE EVENT BEGINS EARLY SUN. LATER SUN AFTERNOON SNOW WILL REMAIN NORTH OF I-70...BUT A MIX OR PLAIN RAIN CAN BE EXPECTED SOUTH OF I-70 AS TEMPERATURES WARM. THE LOW INTENSIFIES AS IT ENTERS THE OHIO RIVER VALLEY...BOLSTERED ALOFT AS TWO JET STREAKS TEMPORARILY PHASE TO MAXIMIZE UPPER LEVEL DIVERGENCE. INTENSIFICATION OF THE LOW WILL AMPLIFY THE LLVL WIND FIELD RESULTING IN A STRONG 50+ KT H85 JET NOSING INTO SWPA. NAM/SREF/GFS ALL SHOW THE TRACK OF THE H85 LOW A LITTLE FURTHER NORTH THAN THAT OF THE ECMWF AND NORTH OF PREVIOUS RUNS. AS THE CLOSED H85 LOW TRACKS THROUGH NCENTRAL OHIO...THIS MEANS THAT WAA WILL BRING POSITIVE H85 ISOTHERMS INTO NRN WV AND SWPA THROUGH EARLY MON MORNING. THIS KEEPS RAIN OR A RAIN/SNOW MIX SOUTH OF I-70 BEFORE THE COLD AIR PUSHES IN ON THE BACKSIDE OF THE LOW MON MORNING. THIS SLIGHTLY WARMER SOLN MARKS THE LARGEST CHANGE MADE TO THE PREVIOUS FORECAST. LARGELY KEPT THE QPF PLACEMENT AND NUMBERS THE SAME...BLENDING THE LATEST WPC GUIDANCE WITH THE PREVIOUS NUMBERS. THE WARMER AIR INVADING UP THE WRN SLOPES OF THE RIDGES WILL WORK TO KEEP OUR SERN ZONES RAIN LONGER AND ULTIMATELY CUT INTO SNOW TOTALS FOR THE DURATION OF THE EVENT. HOW FAR NORTH THAT WARM AIR IS ABLE TO INVADE IS ANOTHER QUESTION. IF THE H85 LOW FOLLOWS THE CURRENT ECMWF TRACK...THE PGH METRO WILL STAY NEARLY ALL SNOW. IF IT FOLLOWS THE MORE NORTHERN TRACK...SEVERAL HOURS OF RAIN DURING THE TIME OF BEST PRECIPITATION COULD CUT INTO THE PGH METRO TOTALS AS WELL. ALL TOLD...A GENERAL 8-10" NORTH ALONG THE I-80 CORRIDOR...BUT TIGHTENED THE ACCUMULATION GRADIENT NEAR THE PGH METRO WITH NRN ALLEGHENY COUNTY IN THE 5-7" RANGE AND SRN PORTIONS OF THE COUNTY IN THE 3-5" RANGE. TRIMMED BACK TOTALS ACROSS THE SRN EXTENT OF THE CWA AS WELL WITH MANY LOCATIONS IN THE 1-3" RANGE. IF THE WARMER SOLNS WIN OUT...NUMBERS ACROSS THE SOUTH COULD BE CLOSER TO THE 1" SIDE OF THAT RANGE. WITH QUESTIONS SURROUNDING THE TRACK AND EXTENT OF WARM AIR...A WELL COLLABORATED DECISION WAS MADE TO HOLD WITH THE WINTER STORM WATCH IN PLACE. TAX && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... LLVL MOISTURE WILL LINGER IN THE HIGH ACROSS THE HIGH TERRAIN THROUGH THE PRE-DAWN HOURS TUES...BUT ANY CHC OF PRECIPITATION WILL BE FLEETING AS SFC HIGH PRESSURE WILL BUILD IN FROM THE WEST. NRN AXIS OF THE SFC RIDGE WILL QUICKLY SHIFT EAST OF THE AREA TUES UNDER ZONAL FLOW ALOFT. SERN EXTENT OF THE HIGH WILL HOLD BACK TO THE WEST...AND WILL TRY TO HOLD THE NEXT SYSTEM OFF TO OUR NORTH. A WEAK SFC LOW PASSES NORTH WEDS...BUT WILL WORK TO AMPLIFY THE UPPER TROF. THE TRAILING COLD FRONT SWINGS THROUGH WEDS NIGHT/THURS MORNING...BRINGING THE BEST CHANCE OF POPS IN THE EXTENDED PERIOD. MUCH COLDER AIR POURS IN BEHIND THE FRONT AS A STOUT HIGH PRESSURE CENTERS OVERHEAD. TEMPERATURES EXPECTED TO BE WELL BELOW AVERAGE FROM MID-WEEK THROUGH THE END OF THE 7 DAY PERIOD. TAX && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
FINGERS OF STRATOCU ARE STARTING TO STREAM IN FROM ACROSS LAKE ERIE. EXPECT THIS VARIABLE AND BORDERLINE MVFR CIG TO IMPACT SEVERAL TERMINALS DURING THE MORNING AND EARLY AFTERNOON AS A WEAK WARM FRONT LIFTS THROUGH. VFR CONDITIONS SHOULD RETURN BY MID TO LATE AFTERNOON...BUT MID/HI CLOUDS WILL BE ON THE INCREASE AHEAD OF OUR SIGNIFICANT SUNDAY STORM. SNOW WILL START ARRIVING FROM THE WEST AFTER MIDNIGHT AND SPREAD EASTWARD WITH TIME...WITH MVFR CIG/VIS DROPPING TO IFR WITHIN AN HOUR OR TWO AFTER SNOW COMMENCES. AREAS EAST OF PIT/MGW MAY AVOID IFR UNTIL AFTER 12Z. WINDS WILL GENERALLY BE 10 KNOTS OR LESS FROM THE SOUTHWEST THROUGH MUCH OF THE TAF PERIOD. CL .OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/... WIDESPREAD RESTRICTIONS CAN BE EXPECTED INTO MONDAY AS A LOW PRESSURE SYSTEM CROSSES THE REGION.
-- End Changed Discussion --
&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR MDZ001. WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ001. OH...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR OHZ039>041-048>050-057>059. PA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR PAZ007>009-013>016-020>023-029-073>076. WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ008- 009-015-016-023-074-076. WV...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR WVZ001>003-023-041. WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ023- 041. && $$

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