Area Forecast Discussion
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000 FXUS61 KPBZ 201405 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1005 AM EDT SAT SEP 20 2014 .SYNOPSIS... DRY AND WARM FOR ONE MORE DAY UNTIL A COLD FRONT BRINGS BRIEF ROUNDS OF SHOWERS AND THUNDERSTORMS SUNDAY. MUCH COOLER MONDAY...HOWEVER A WARMING TREND WILL ENSUE EACH DAY NEXT WEEK WITH HIGH PRESSURE CAMPED OUT OVER THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ONE LAST WARM DAY BEFORE A COLD FRONT APPROACHING FROM THE WEST TAKES THE WEATHER AND TEMPERATURES DOWNHILL. THE LATEST 12Z PIT RAOB ILLUSTRATES LOTS OF DRY AIR FROM H7 THROUGH H4 WHICH WILL MIX OUT MOST OF THE LOW LEVEL MOISTURE NOTED NEAR THE SURFACE. NONETHELESS STILL EXPECT CUMULUS DEVELOPMENT DURING THE AFTERNOON AS TEMPERATURES CLIMB INTO THE MID 70S. THE MAIN WEATHER STORY THIS AFTERNOON WILL BE GUSTY WINDS. PRESSURE GRADIENT INCREASES WITH LOW PRESSURE ENCROACHING FROM THE MIDWEST AND A FAIRLY DEEP MIXING LAYER. AFTERNOON MIXING HEIGHTS WILL BE AROUND 5-6KFT EQUATING TO GUSTS AROUND 30 MPH. NAM IS GENERATING ISOLD STORMS OVER THE HIGHER TERRAIN THIS AFTERNOON...HOWEVER DUE TO THE INFLATED LLVL MOISTURE THAT ITS PREDICTING...IGNORED IT AND CONTINUE WITH A DRY FCST AREA WIDE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... ATMOSPHERIC MOISTURE WILL BE INCREASING SATURDAY NIGHT AHEAD OF A COLD FRONT THAT WILL SLOWLY MOVE THROUGH THE MIDWEST. PRE-FRONTAL SHORTWAVE TROUGH WILL SWING THROUGH SATURDAY NIGHT. THE UPPER LEVEL ENERGY WEAKENS AS IT MOVES THROUGH AND IT WILL BE ENCOUNTERING A RATHER STABLE ATMOSPHERE. WILL KEEP POPS LOW SATURDAY NIGHT AS SHORTWAVE MAY PROVIDE MORE CLOUDS THAN PRECIPITATION. FRONT REACHES WESTERN ZONES BY LATE SUNDAY MORNING. MODELS CONTINUE TO SHOW A DESTABILIZING ATMOSPHERE AND AN IMPRESSIVE WIND FIELD AHEAD OF THE SURFACE BOUNDARY...BUT CONTINUE TO SEE A LACK OF UPPER LEVEL SUPPORT. THE CLOUD COVER FROM SATURDAY NIGHTS SHORTWAVE WILL LIMIT THE AMOUNT OF SUNSHINE SUNDAY MAKING IT DIFFICULT TO REACH CONVECTIVE TEMPS. A SIGNIFICANT LINE OF LOW LEVEL FORCING DEVELOPS ALONG THE BOUNDARY SUNDAY AFTERNOON AS MOISTURE CONVERGENCE IN THE LOWEST LAYERS INCREASES. 0-6 KM BULK SHEAR VALUES ARE STILL IMPRESSIVE...BUT MUCH WILL DEPEND ON THE CLOUD COVER AND HOW THIS LIMITS SURFACE TEMPS. ADDITIONALLY...ANY SHOWERS THAT FALL WITH THE PRE-FRONTAL SHORTWAVE WILL COOL THE ATMOSPHERE...FURTHER DECREASING THE THREAT FOR STRONGER STORMS. SUNDAY`S FRONT WILL NEED TO BE WATCHED AS THE POTENTIAL IS THERE FOR A STRONGER EVENT...BUT SO ARE THE LIMITING FACTORS. IF A LINE OF STRONGER STORMS DEVELOPS IT WILL BE DIRECTLY AHEAD OF THE BOUNDARY. FRONT PICKS UP SPEED SUNDAY EVENING AS STRONG SHORTWAVE DIGS INTO THE UPPER OHIO VALLEY. STRONG CAA AND NORTHWEST FLOW WILL FOLLOW THE SHORTWAVE. WOULD EXPECT A LARGE STRATOCU DECK TO MOVE OVER THE REGION LATE SUNDAY NIGHT AND THROUGH A LARGE PART OF MONDAY. ITS POSSIBLE THAT A COUPLE OF ROUNDS OF SHOWERS WILL DEVELOP...SUNDAY NIGHT WITH THE SHORTWAVE...AND AGAIN MONDAY AFTERNOON WITH THE MAIN COLD POOL. WILL GO BELOW GUIDANCE FOR TEMPS ON MONDAY WITH THE CAA AND CLOUD COVER. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... DRY PATTERN IS EXPECTED FOR THE REMAINDER OF THE LONG TERM PERIOD. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS CONDITIONS TODAY WITH GUSTY SOUTHWESTERLY WINDS DEVELOPING BY LATE THIS MORNING AS STRONGER WINDS ALOFT MIX DOWN TO THE SURFACE. OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY... GENERAL RESTRICTIONS AND GUSTY WINDS ARE LIKELY SUNDAY AS A COLD FRONT IMPACTS THE REGION WITH A LINE OF THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WINDS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SYNOPSIS...98 NEAR TERM...98 SHORT TERM...22 LONG TERM...88 AVIATION...88

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