Area Forecast Discussion
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000 FXUS61 KPBZ 211359 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 959 AM EDT THU MAY 21 2015 .SYNOPSIS... COOL TEMPERATURES WILL REMAIN THROUGH LATE WEEK. A WEAK DISTURBANCE WILL BRING SHOWERS MAINLY FROM PITTSBURGH SOUTH THIS MORNING. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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AN INVERTED TROUGH IS SET TO SLOWLY ERODE ALONG THE WEST SLOPES OF THE RIDGES AS LARGE SCALE FLOW WILL START TO TURN MORE NORTHWESTERLY THIS AFTERNOON. THIS WILL BEGIN TO BECOME LESS FAVORABLE TO DOWNSLOPE TROUGHING WEST OF THE RIDGES...AND ALLOW FOR THE PRECIPITATION FIELD TO CONTINUE TO ERODE FROM THE WEST IN THE SOUTHEASTERN PORTIONS OF THE AREA. IN THE COLD ADVECTION REGIME AS FLOW TURNS MORE NORTHWESTERLY...TEMPERATURES AROUND 800 MB SAG A FEW DEGREES CELSIUS THROUGH THE AFTERNOON...WHILE THE BOUNDARY LAYER WARMS SLIGHTLY. THIS SHOULD ALLOW FOR STRATUS TO HANG ON FOR THE MOST PART THROUGH THE REST OF THE DAY. ANY SUN BREAKS THAT DO OCCUR SHOULD BE DESTRUCTIVE AS WARMING WILL ONLY ENCOURAGE MORE CLOUD DEVELOPMENT. BECAUSE OF THIS...MOSTLY CLOUDY SKIES WERE FAVORED RIGHT THROUGH THE DAY. THIS WILL KEEP TEMPERATURES RANGEBOUND IN THE MIDDLE AND UPPER 50S. FRIES
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... CLOSED LOW OVER EASTERN CANADA WILL WOBBLE SOUTH FRIDAY...DEEPENING UPPER TROUGH AND PUSHING A MOISTURE STARVED COLD FRONT ACROSS THE REGION. ONLY SLIGHT CHANCE POPS WITH THE FRONT AS IT CROSSES THE REGION DURING THE DAY FRIDAY AND EXITS THE RIDGES BY EVENING. A GOOD COLD PUNCH BEHIND FRONT WITH DRY SURFACE HIGH BUILDING OVER THE REGION FRIDAY NIGHT. WITH CLEAR SKIES AND LIGHT WINDS...TEMPERATURES WILL FALL INTO THE LOWER AND MID 30S NORTH AND RIDGES WITH AREAS OF FROST EXPECTED. ELSEWHERE LOOKS TO BE BORDERLINE FOR FROST AND ADDED PATCHY FROST EXCEPT FOR THE ZANESVILLE AREA FOR NOW. LATER SHIFTS WILL BE BETTER ABLE TO DEFINE. SUNSHINE AND A RETURN TOWARD SEASONAL TEMPERATURES SATURDAY. AS SURFACE RIDGE SHIFTS EAST SUNDAY CLOUDS WILL INCREASE AHEAD OF A WARM FRONT WITH HIGHS IN THE 70S. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... UPPER RIDGING OVER THE SOUTHEAST CONUS IS EXPECTED TO DEVELOP BY EARLY NEXT WEEK...AS SHORTWAVES ADVANCE ALONG THE NORTHERN PERIPHERY OF THE RIDGE. MAINTAINED CHANCE POPS FOR THE HOLIDAY FORECAST AS THE STRENGTH OF RIDGING AND PLACEMENT OF A SURFACE BOUNDARY ACROSS THE AREA REMAIN IN QUESTION. SOUTHWEST FLOW IS PROGGED TO DEVELOP THEREAFTER WITH OCCASIONAL WEAK EMBEDDED CROSSING SHORTWAVES. THIS WILL CONTINUE PERIODIC CHANCES FOR SHOWERS/STORMS. USED WPC BASED ENSEMBLE MEAN GUIDANCE WITH DOWNWARD ADJUSTMENTS TO POPS TO HELP SMOOTH OUT INDIVIDUAL MODEL DIFFERENCES...ESPECIALLY FOR MONDAY. TEMPERATURES SHOULD AVERAGE ABOVE SEASONAL LEVELS. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... A WEAK SHORTWAVE TROUGH IS EXPECTED TO EXIT THIS MORNING ENDING ANY SHOWERS FROM WEST TO EAST. MAINLY VFR CEILINGS ARE EXPECTED TO CONTINUE TODAY AS ANOTHER UPPER TROUGH CROSSES... THOUGH PORTS SOUTH OF THE PA/WV BORDER ARE EXPECTED TO SEE MVFR STRATOCU WITH A PERIOD OF IFR THIS MORNING WHERE BETTER LOW LEVEL MOISTURE IS IN PLACE. CLOUDS SHOULD SCATTER OUT LATE THIS EVENING AFTER THE PASSAGE OF THE UPPER TROUGH. .OUTLOOK.../FRIDAY THROUGH MONDAY/... RESTRICTIONS ARE POSSIBLE WITH A LATE SUNDAY AND MONDAY WARM FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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