Area Forecast Discussion
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000 FXUS61 KPBZ 231215 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 815 AM EDT THU APR 23 2015 .SYNOPSIS... COLD WEATHER WILL CONTINUE WITH SCATTERED SNOW AND RAIN SHOWERS PLAGUING THE REGION TODAY. THE NEXT CHANCE FOR RAIN IS FORECAST WITH CROSSING LOW PRESSURE ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/...
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STRONG LOW LEVEL LAPSE RATES CONTINUE TO LINGER OVER THE AREA AS CYCLONIC FLOW HOLDS SWAY OVER THE UPPER OHIO VALLEY FOR THE FORSEEABLE FUTURE. WITH NORTHWESTERLY FLOW AND COLD ADVECTION CONTINUING...ALONG WITH FAIRLY STRONG SURFACE DEWPOINT DEPRESSIONS...STRONG LAPSE RATES ABOVE THE SURFACE...A DECENT AMOUNT OF POSITIVE AREA BELOW THE DENDRITIC GROWTH ZONE...AND SATURATION EXTENDING INTO THE LOWER PORTION OF SAID ZONE...THE STAGE IS SET AGAIN TODAY FOR A COMBINATION OF RAIN SHOWERS...SNOW SHOWERS...GRAUPEL...AND EVEN SOME SMALL HAIL IN THE MORE BURLY SHOWERS THAT DO DEVELOP. WHILE LARGE SCALE SUPPORT FOR ASCENT IS SOMEWHAT LACKING...A DIURNALLY-DRIVEN UPTICK IN INSTABILITY SHOULD MANAGE TO MUSTER A BIT OF AN INCREASE IN SHOWER ACTIVITY COME AFTERNOON. HOWEVER...GIVEN THE BOUNCING NATURE OF TEMPERATURES THAT WILL BE LIKELY GIVEN THE WIDE SURFACE DEWPOINT DEPRESSIONS...ANY ACCUMULATION OF FROZEN PRECIPITATION SHOULD BE MINIMAL AND SHORT-LIVED IF IT DOES OCCUR ANYWHERE. THAT SAID...MOSTLY CLOUDY SKIES DO SEEM LIKELY TO RULE THE ROOST AS STRATOCUMULUS SHOULD INCREASE IN COVERAGE BY AFTERNOON. THIS WILL AGAIN HOLD TEMPERATURES BACK WELL BELOW SEASONAL NORMS FOR LATE APRIL. FRIES
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY/... THAT HIGH WILL MAINTAIN DRY WEATHER THROUGH FRIDAY NIGHT ALTHOUGH HEIGHTS WILL RISE IN RESPONSE TO MIDWESTERN TROUGHING. THAT TROUGH IS PROJECTED TO PROGRESS EASTWARD AND PHASE WITH THE NEW ENGLAND LOW...HENCE RESULTING IN A REINFORCED EASTERN CONUS TROUGH FOR THE START OF NEXT WEEK. INITIAL PRECIP ONSET ASSOCIATED WITH THE ADVANCE OF THE SYSTEM IS NOW PROGGED FOR A LATER SATURDAY START AS MODEL SOLUTIONS HAVE SLOWED CONSIDERABLY OVER THE PAST 24 HOURS. PRIMARY CHANGES TO THE FORECAST WILL THUS INVOLVE POPS ADJUSTMENTS FOR SUNDAY TO ACCOUNT FOR THE SLOWER EXIT. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... UPPER LEVEL LOW WILL SIT AND SPIN OVER NEW ENGLAND SUNDAY NIGHT INTO MONDAY NIGHT. MOISTURE WILL SPILL INTO WESTERN PENNSYLVANIA BY MONDAY MORNING...AND A SHORTWAVE PIVOTING AROUND THE UPPER LOW WILL BRING AT LEAST A SLIGHT CHANCE OF PRECIPITATION FOR PENNSYLVANIA COUNTIES FOR MONDAY INTO MONDAY NIGHT. CANNOT RULE IN A FEW SNOWFLAKES MIXING IN RIGHT AROUND SUNRISE FOR FOREST...CLARION...AND JEFFERSON COUNTIES BOTH MONDAY AND TUESDAY MORNINGS. BY THE TIME THE UPPER LOW MOVES OFFSHORE TUESDAY...A SURFACE LOW WILL BEGIN DEVELOPING ALONG THE GULF COAST AND MOVE TO THE NORTHEAST. THE ECMWF KEEPS THE LOW WELL EAST OF THE REGION WITH NO RAIN LOCALLY...BUT THE GFS ALONG WITH THE UKMET AND THE NAEFS KEEPS THE LOW CLOSER TO THE COAST AND SPREADS RAIN INTO THE REGION. HAVE BUMPED UP POPS WEDNESDAY...ALTHOUGH FUTURE MODEL RUNS WILL BE NEEDED TO DETERMINE THE EXACT TRACK OF THE LOW. WITH SOME SORT OF NORTHERLY FLOW EXPECTED THROUGH THE EXTENDED FORECAST AND MUCH CLOUD COVER WITH THE TWO MAIN SYSTEMS...TEMPERATURES WILL CONTINUE TO BE BELOW NORMAL...BUT WILL RISE CLOSER TO CLIMATOLOGICAL VALUES BY THE END OF THE PERIOD.THE EASTERN CONUS TROUGH AND RESULTING NORTHWESTERLY WIND WILL CONTINUE TO HOLD TEMPERATURES UNDER THE AVERAGES. HAVE TRENDED TOWARDS WPC NUMBERS WHICH KEEP AT LEAST SOME CHANCE OF PRECIPITATION IN THE FORECAST. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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MAINLY VFR STRATOCU CIGS ARE EXPECTED TODAY ALONG WITH SCATTERED RAIN/SNOW SHOWERS AS A PERSISTENT UPPER TROUGH REMAINS ACROSS THE GREAT LAKES. THINK THAT FKL/DUJ WILL HAVE BOTH THE GREATEST CHANCE FOR SHOWERS AS WELL AS MVFR CIG DEVELOPMENT. WEST TO NORTHWEST WIND COULD GUST TO 20-25 KTS DURING THE AFTERNOON AS WELL. .OUTLOOK.../FRIDAY THROUGH MONDAY/... RESTRICTIONS ARE POSSIBLE SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON AS LOW PRESSURE TRACKS ACROSS THE OHIO VALLEY.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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