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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 171814 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 214 PM EDT FRI OCT 17 2014 .SYNOPSIS... A STRONG COLD FRONT ADVANCES ACROSS THE REGION LATE TONIGHT AND SATURDAY WITH RAIN CHANCES THROUGH SUNDAY MORNING. && .NEAR TERM /THROUGH SATURDAY/... CURRENT VISIBLE SATELLITE IMAGE SHOWS LOW STRATUS ACROSS OUR NERN ZONES ERODING FROM THE WEST WITH CLEAR SKIES TAKING ITS PLACE. STRIATIONS IN THE LLVL CLOUD DECK INDICATE STRONG FLOW AND THE REMNANTS OF AN INVERSION NEAR 2KFT. FURTHER MIXING AND LLVL WAA WILL CONTINUE TO ERODE THE INVERSION AND SUBSEQUENT CLOUD COVER. MOSTLY CLEAR CONDITIONS SHOULD PERSIST ACROSS THE SOUTH THROUGH THE EVENING. VERY BRIEF ZONAL UPPER LEVEL FLOW MODIFIES TONIGHT AS A STRONG SHORTWAVE TROF DROPS SOUTH OUT OF THE WRN GREAT LAKES. COLD FRONT ASSOCIATED WITH THE UPPER LOW IS CURRENTLY SPLAYED THROUGH ERN MI SOUTH THROUGH THE LOWER OHIO VALLEY. LLVLS AHEAD OF THE COLD FRONT HAVE WARMED TODAY THROUGH STRONG WAA. ACROSS THE FRONT...SFC TEMP GRADIENT IS QUITE SMALL...BUT A DEWPOINT GRADIENT AND WIND SHIFT IS NOTED. MOISTURE BEGINS TO POOL TO OUR NW TONIGHT AS THE SHORT WAVE TROF PUSHES SOUTH APPROACHING LAKE ERIE. BEING THAT THE AIR MASS TRANSITION BEHIND THE FRONT IS ONE OF CONTINENTAL ORIGINATION...AND MOISTURE FEED INTO THE LOW IS THE LEFTOVERS FROM THE REMNANT BROAD LOW OVER ERN ONTARIO...MOISTURE AVAILABILITY IS NOT OVERLY IMPRESSIVE. ALSO...WEAK ASCENT IN THE LOW LEVELS WILL INITIALLY QUELL THE ONSET OF PRECIPITATION...BUT AS THE UPPER TROF AXIS APPROACHES WIND FIELDS STRENGTHEN THROUGH THE COLUMN ADVECTING IN MUCH COLDER AIR FROM H9 ON UP. LAPSE RATES WILL ACTUALLY STEEPEN OVERNIGHT INTO EARLY SAT...GENERATING SHOWERS FOR MOST LOCATIONS...BUT WILL BE MORE LIKELY ACROSS THE NORTH WITH THE RELATIVELY DEEPER MOISTURE. MAIN TROF AXIS SHIFTS EAST BY MIDDAY SAT AS LLVL FLOW KEEPS POOLING MOISTURE UP THE HIGHER TERRAIN...THUS EXPECTING SHOWERS TO HOLD IN THE RIDGES A LITTLE LONGER. ANOTHER RE-ENFORCING SW TROF SWINGS THROUGH SAT EVENING GENERATING RAIN SHOWERS OUT OF THE REMAINING MOISTURE. 12Z NAM IS A LITTLE BIT COLDER THAN THE PREVIOUS VERSIONS...BUT ONLY BRINGS IN -1C TO -2C AT H85 BEFORE THE MOISTURE DRIES UP SAT...SO KEPT ALL HYDROMETEORS IN THE LIQUID STATE. TAX && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... STRONG COLD FRONT WILL MOVE TOWARD THE AREA TONIGHT. IMPRESSIVE SHORTWAVE TROUGH WILL SWING THROUGH AHEAD OF BOUNDARY...SPARKING SHOWERS...WHICH WILL MOVE SOUTHEASTWARD FROM THE GREAT LAKES. FAST MOVING BOUNDARY WILL BE RIGHT BEHIND THE SHORTWAVE AND WILL CROSS THE REGION AROUND DAWN SATURDAY. STRONG CAA WILL BEGIN BEHIND THE FRONT AND THE FLOW AT 850 WILL VEER TO THE NORTHWEST. 850 TEMPS WILL DROP FROM +3 TO -3 DURING THE DAY ON SATURDAY. THE FLOW...COMBINING WITH THE CAA WILL MEAN LOTS OF CLOUDS...SCATTERED LAKE EFFECT SHOWERS AND STEADY OR SLOWLY FALLING TEMPS. ANOTHER SHORTWAVE TROUGH WILL DESCEND ACROSS THE REGION SATURDAY NIGHT. THIS WILL PROVIDE ANOTHER SHOT OF COLD AIR AND WILL KEEP IN THE CLOUDS AND SCATTERED SHOWERS. ITS VERY POSSIBLE THAT THE RIDGE TOPS COULD SEE SOME SNOW MIXING LATE SATURDAY NIGHT. MODEL THICKNESSES ARE NOT QUITE COLD ENOUGH AND FORECAST SOUNDINGS ARE SHOWING A LAYER ABOVE FREEZING THAT MAY BE JUST DEEP ENOUGH...BUT WITH 850MB TEMPS TOUCHING -4...THE CHANCE CAN`T BE IGNORED. WILL CONTINUE WITH THE MENTION OF SNOW ABOVE 2500 FT. SLOW IMPROVEMENT ON SUNDAY AS THE COLD AIR BEGRUDGINGLY SHIFTS TO THE NORTHEAST. SURFACE HIGH WILL MOVE THROUGH OHIO ALLOWING FOR A SLOW DECREASE IN CLOUD COVER FROM WEST TO EAST. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... DRY SUNDAY NIGHT...BUT CHILLY. NEXT SYSTEM WILL SWING DOWN FROM THE NORTH MONDAY AND DEEPEN AS IT SLOWLY CROSSES THE AREA. MODELS ARE SHOWING THE SYSTEM CUTTING OFF AND LINGERING NEAR THE REGION THROUGH MIDWEEK. HIGH PRESSURE BUILDS IN FOR THE END OF THE LONG TERM. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... LAST BIT OF MVFR STRATUS LINGERING ACROSS NRN PORTS. GENERALLY VFR IS EXPECTED FROM THROUGH THE EVENING WITH CLEARING SKIES. GUSTY SW WINDS CURRENTLY REPORTED THROUGH THE AREA ARE EXPECTED TO CONTINUE THROUGH TONIGHT...ALTHOUGH THEY SHOULD BEGIN TO VEER TO THE WEST AS THE NEXT SYSTEM APPROACHES TONIGHT. LLVL MOISTURE APPROACHES LATE TONIGHT AS AN UPPER LEVEL TROF DROPS OUT OF THE GREAT LAKES. EXPECTING CIGS TO LOWER IN RESPONSE TO THE ADDED MOISTURE IN THE COLUMN. IN GENERAL...EXPECTING MVFR CIGS ACROSS THE SOUTH INCLUDING KPIT...BUT NRN PORTS SHOULD DROP TO IFR. RAIN SHOWERS ALSO POSSIBLE FROM 06Z THROUGH THE REMAINDER OF THE TAF PERIOD. TAX .AVIATION /FRIDAY NIGHT THROUGH TUESDAY/... PERIODIC RESTRICTIONS POSSIBLE THROUGH SUNDAY MORNING WITH ANOTHER WEAK SYSTEM SAT NIGHT. RESTRICTIONS ALSO POSSIBLE AGAIN MON NIGHT/TUES AS ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE NW. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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