Area Forecast Discussion
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000 FXUS61 KPBZ 232251 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 551 PM EST TUE DEC 23 2014 .SYNOPSIS... MIDWESTERN LOW PRESSURE WILL BRING A COLD FRONT AND STRONG WIND TO THE UPPER OHIO REGION FOR CHRISTMAS. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... THE EARLY EVE UPDATE INCLUDED A NR TERM POP UPDATE BASED ON THE LATEST RADAR TRENDS AS WELL AS A WIND GUST INCRS FOR WEDNESDAY NGT. DEEPENING LOW PRES WL TRACK W OF THE IMMEDIATE AREA AND OVR THE GREAT LAKES DURING THE NXT 24 HOURS. RAIN CHCS WL INCRS TO CATEGORICAL LVLS ON THE STRENGTH OF WARM...MOIST ADVCTN...AND CONT WITH THE ADVN OF THE SYSTEMS CDFNT OVR THE REGION ON WEDNESDAY NGT. PROGRESSION AND A LACK OF SUSTAINED CNVRGNC SHOULD LIMIT BASIS AVG RAIN TOTALS TO AN INCH OR LESS FOR THE PD. RFC GUIDANCE...WITH ADJUSTMENTS FOR LOCAL POP TRENDS...WAS USED FOR THE QPF FORECAST. THE MAIN PROBLEM WITH THIS PARTICULAR SYSTEM WL BE THE POTENTIAL FOR DAMAGING WIND WITH PASSAGE OF...AND IMMEDIATELY BEHIND THE COLD FRONT ON WEDNESDAY NGT. UNTIL THEN...STRONG WARM ADVCTN WL CAP THE SFC ON WEDNESDAY...HENCE INHIBITING MIXING...GUSTS...SFC BASED CONVECTION. A THUNDER CHC WL BE MAINTAINED HOWEVER...DUE TO A LTD ELEVATED POTENTIAL. THE INVERSION RESULTING FM THE AFOREMENTIONED WARM SURGE IS PROJECTED TO BE RELATIVELY SHALLOW...HENCE A DEEPENED MIXING LYR RESULTING FM THE FRONT BNDRY PLOWING ACRS THE REGION ON WEDNESDAY EVE IS EXPECTED TO BE SUFFICIENT TO SPPRT AT LEAST ADVISORY LVL GUSTS...WITH MORE DAMAGING SPEEDS CERTAINLY POSSIBLE...ESPECIALLY IN LGT OF EXPECTED ISALLOBARIC ACCELERATION ANTICIPATED ON A VERY STRONG PRES SURGE. FOR NOW...GENL WED NGT GUSTS WERE INCRSD TO 40 MPH AND A HAZARDOUS WEATHER OUTLOOK MENTIONED MAINTAINED FOR A POTENTIAL ADVISORY...WHICH MAY BE AUGMENTED BY STORM PREDICTION CENTER PARTICIPATION IN A SHALLOW CONVECTIVE EVENT. && .SHORT TERM /THURSDAY AND FRIDAY/... WINDY CONDITIONS AND PCPN CHCS WL BE ALLEVIATED LTR ON THURSDAY AS THE PRES GRADIENT RELAXES WITH BLDG HIGH PRES. THEREAFTER...A SHORTWAVE CROSSING THE GREAT LAKES MAY CAUSE RAIN/SNOW SHOWERS ON SATURDAY. TEMPERATURES FOLLOWING THE FRONTAL PASSAGE WILL LOWER TOWARDS SEASONAL AVERAGES BUT REMAIN SLIGHTLY WARMER THAN NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ANOTHER FRONTAL SYSTEM IS PROJECTED TO IMPACT THE REGION OVER THE WEEKEND. MODELS CONTINUE TO SHOW RELATIVELY POOR CONSENSUS WITH THIS SYSTEM SO HAVE OPTED TO WEIGH HEAVILY ON ENSEMBLE GUIDANCE IN MAKING ANY ADJUSTMENTS TO THE ONGOING FORECAST. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... RAIN RETURNS LATER TONIGHT AS SURFACE LOW GETS ORGANIZED OVER THE TENNESSEE VALLEY...DROPPING CIG/VIS INTO MVFR AND THEN IFR CATEGORY AFTER 07Z OR SO. HAVE SOME SLIGHT IMPROVEMENT BACK TO MVFR AROUND 14/15Z AHEAD OF COLD FRONT...WHICH SWEEPS THROUGH AFTER THE TAF PERIOD. OUTLOOK.../WEDNESDAY THROUGH SUNDAY/... CIG/VIS RESTRICTIONS THROUGH THURSDAY WILL IMPROVE TO VFR FRIDAY AND CONTINUE UNTIL ANOTHER FRONTAL SYSTEM CROSSES THE REGION SATURDAY AFTERNOON. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ 15

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