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 240207 AAB AFDPBZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 907 PM EST FRI JAN 23 2015 .SYNOPSIS... LOW PRESSURE SYSTEM MOVING UP THE COAST WILL BRING RAIN AND SNOW TO TONIGHT AND SATURDAY. A SECOND SYSTEM WILL IMPACT THE REGION SUNDAY. && .NEAR TERM /THROUGH SATURDAY/... 915PM UPDATE...CONTINUE TO STRUGGLE WITH PRECIP TYPE FROM SYSTEM. HAVE BEEN USING OBS AND LATEST GUIDANCE TO WORK THROUGH IT. TEMPS HAVE BEEN UPDATE AS WELL. PREVIOUS DISCUSSION... COMPLEX LOW PRESSURE SYSTEM DEVELOPING OVER THE GULF WILL SLIDE NORTHEASTWARD ALONG THE COAST THROUGH SATURDAY. PRECIPITATION SHIELD WITH THIS SYSTEM IS ALREADY MAKING IT INTO THE SOUTHERN ZONES BUT DRY AIR AT THE SURFACE HAS YET TO BE OVERCOME. THIS SHOULD QUICKLY CHANGE AS THE LOW LEVELS SATURATE. INITIAL PRECIP TYPE REMAINS A BIT OF AN ISSUE AS SURFACE TEMPERATURES ARE IN THE MID TO UPPER 30`S BUT DEWPOINTS ARE IN THE MID 20`S. THINK THAT WETBULBING WILL ALLOW FOR SNOW AT ONSET BUT A MIX OF RAIN AND SNOW IS EXPECTED...ESPECIALLY SOUTH OF I-70. TODAY`S MODEL RUNS HAVE SHIFTED THE SYSTEM A BIT MORE TO THE NORTH AND WEST...WHICH BRINGS HIGHER QPF INTO OUR RIDGE COUNTIES BUT ALSO BRINGS WARMER TEMPERATURES ALOFT. A KEY FEATURE THAT DOES SEEM TO BE PRESENT IN ALL OF THE MODEL RUNS TODAY IS THE DEVELOPMENT OF A DEFORMATION ZONE WHICH COULD IMPACT A PORTION OF OUR AREA OVERNIGHT. BELIEVE THIS IS DRIVING THE HIGHER QPF AND SNOW FALL TOTALS ACROSS OUR REGION. WITH IT CONSISTENT AMONG ALL THE MODELS...OPTED TO BUMP UP SNOW AMOUNTS ACROSS THE SOUTH WHICH BROUGHT 6 INCHES INTO GARRETT AND TUCKER COUNTIES AND ADVISORY AMOUNTS INTO THE HIGHER ELEVATIONS OF WESTMORELAND AND FAYETTE. THUS...HAVE UPGRADED FORMER TO A WINTER STORM WARNING AND THE LATTER TO A WINTER WEATHER ADVISORY. FURTHER NORTH AND WEST...SNOW AMOUNTS WERE ALSO ADJUSTED UPWARD BUT REMAIN UNDER 3 INCHES AT THIS TIME. STEADY PRECIP AND A LACK OF ANY REAL TEMPERATURE ADVECTION SHOULD KEEP TEMPERATURES FROM MOVING MUCH THROUGH THE OVERNIGHT PERIOD. THE LOW PRESSURE SYSTEM AND PRECIP WILL SHIFT TO THE EAST BY MIDDAY SATURDAY...AS AN UPPER WAVE/COLD FRONT SHIFTS ACROSS THE GREAT LAKES. BOTH THE NAM AND THE GFS SUGGEST THE PRESENCE OF JUST ENOUGH MOISTURE IN NW FLOW TO BRING SOME LIGHT SNOW TO MOST OF THE REGION THROUGH THE AFTERNOON SATURDAY. SINCE MOST OF THE MOISTURE WILL BE BELOW THE DENDRITIC GROWTH ZONE...KEPT CHANCE POPS ACROSS MOST OF THE REGION THROUGH SATURDAY EVE FOR NOW. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... SHORTWAVE TROUGH WILL DEEPEN AS IT DROPS SOUTH OVER THE UPPER MIDWEST SATURDAY NIGHT AND SUNDAY AS THE ASSOCIATED UPPER LEVEL JET CORE HELPS AMPLIFY THE OVERALL LONGWAVE PATTERN. LATEST GUIDANCE INDICATES THE WAVE CLOSING OFF IN THE LOWER LEVELS BY SUNDAY EVENING WITH H925 AND H850 BECOMING EASTERLY AROUND 25-30KTS ON AVERAGE. ATTM UPPER LEVEL DYNAMICS LOOK FAVORABLE FOR A 6-12 HR PERIOD OF MORE INTENSE SNOW DEVELOPING BY MID SUNDAY EVENING WITH PRESSURE ADVECTION AT PV15 OVERLAYING AREAS OF FRONTOGENESIS AT LOWER LEVELS. OVERALL MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH PROGGED SNOW AMOUNTS WITH ABOUT 4 INCHES ON AVERAGE...WITH HIGHER TOTALS ACROSS SOUTHERN ZONES. THE PROBLEM IS THAT PLACEMENT HAS BEEN INCONSISTENT AND OVER THE PAST 24 HOURS MODELS HAVE TRENDED FARTHER SOUTH/DEEPER WITH THE FEATURE. LATEST FORECAST REFLECTS A BLEND OF THE LATEST GUIDANCE WITH A SLIGHT ADJUSTMENT TO THE SOUTH ANTICIPATING MODELS CONTINUE THE OBSERVED TREND. WITH THAT...HAVE OPTED TO HOLD OFF ON ANY HEADLINES FOR NOW...BUT SHOULD HAVE BETTER CONFIDENCE IN DETAILS OVER THE NEXT 24 HOURS OR SO. IN ANY CASE...ADVISORY LEVEL SNOWFALL LOOKS LIKELY FOR A LARGE PART OF THE FORECAST AREA. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE LONG TERM FORECAST WL FEATURE MODERATING TEMPS AFTR A COLD FIRST HALF OF THE WEEK AS THE ERN CONUS TROF FILLS. SFC HIGH UNDR FLAT SHRTWV RIDGING SHOULD SUPPRESS PCPN UNTIL THE APCH OF LATE WEEK LOW PRES. LITTLE DEVIATION FM WPC GUIDANCE WAS NEEDED. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... VFR TO START...BUT CONDITIONS WILL DETERIORATE FROM THERE AS LOW PRESSURE MOVES OFFSHORE NEAR THE DELMARVA AND SPREADS PRECIPITATION INTO THE AREA. EXPECTING MOST TERMINALS TO DROP TO MVFR TO IFR TONIGHT IN RA/SN MIX CHANGING TO MAINLY SNOW...ALTHOUGH FKL/ZZV WILL REMAIN ON THE WESTERN FRINGES AND MAY ONLY SEE AN MVFR CIG WITH LITTLE PRECIP. HEAVIEST SNOW AT TAF SITES WILL BE SEEN AT MGW AND LBE. SLOW IMPROVEMENT BACK TO MVFR FORECAST SATURDAY MORNING...WITH STRATOCU MVFR CIG HOLDING THROUGH THE REST OF THE PERIOD AREAWIDE. WINDS WILL BE LIGHT AND VARIABLE TONIGHT AND TOMORROW MORNING BEFORE INCREASING FROM THE WNW DURING THE AFTERNOON. .OUTLOOK.../SATURDAY THROUGH WEDNESDAY/... CROSSING LOW PRES IS LIKELY TO SPAWN RESTRICTIONS OVR ALL TERMINALS ON SUNDAY AND MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WARNING UNTIL 10 AM EST SATURDAY FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST SATURDAY FOR PAZ074- 076. WV...WINTER WEATHER ADVISORY UNTIL 10 AM EST SATURDAY FOR WVZ023. WINTER STORM WARNING UNTIL 10 AM EST SATURDAY FOR WVZ041. && $$

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