Area Forecast Discussion
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000 FXUS61 KPBZ 040016 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 816 PM EDT FRI JUL 3 2015 .SYNOPSIS...
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RAIN WILL CONTINUE WITH CROSSING LOW PRESSURE TONIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BUILD OVERHEAD FOR THE REMAINDER OF THE HOLIDAY WEEKEND. WARMER WEATHER CAN BE EXPECTED FOR THE START OF THE NEW WEEK.
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&& .NEAR TERM /THROUGH SATURDAY/... AREA OF SHOWERS AND ISOLATED THUNDER CONTINUES TO MAKE NORTHWARD PROGRESS A BIT AHEAD OF PREVIOUS GUIDANCE. HAVE AGAIN ADJUSTED POPS UP AND SHIFTED HIGHER POPS A BIT MORE NORTHWEST. OTHERWISE NO CHANGES...PREVIOUS DISCUSSION FOLLOWS. UPPER DIFFLUENCE IS SET TO INCREASE THIS EVENING AS A WEAK SHORT WAVE AND CLOSED 850 MB CIRCULATION TRACK TOWARD THE UPPER OHIO VALLEY AHEAD OF THE UPPER WAVE. THIS WILL ALLOW FOR SHOWER ACTIVITY TO INCREASE FROM SOUTH TO NORTH GOING INTO THE LATE AFTERNOON HOURS. INSTABILITY IS FAR FROM IMPRESSIVE...AND GIVEN MODEL SOUNDINGS REALLY ONLY PROJECTING POSITIVE AREA MAINTAINING ITSELF ABOVE THE FREEZING LEVEL IN THE SOUTHEASTERNMOST PORTIONS OF THE CWA...THUNDERSTORM CHANCES WERE RELEGATED GENERALLY TO THE RIDGES AND POINTS NEARBY. HOWEVER...GIVEN DECENT LIFT AND FAIRLY HEFTY LAYER RH VALUES...CHANCES OF RAIN WERE INCREASED TO CATEGORICAL ACROSS THE SOUTHEASTERN QUARTER OF THE CWA FROM LATE THIS AFTERNOON INTO THIS EVENING. THE AFOREMENTIONED UPPER WAVE IS SLOW TO MOVE EASTWARD GOING INTO THE OVERNIGHT HOURS. THIS SHOULD ALLOW FOR SOUTHERLY FLOW TO DOMINATE THE SCENE. WITH JET CURVATURE INCREASING THROUGH THE NIGHT AND THE RIGHT ENTRANCE REGION REMAINING IN THE REGION...SHOWER CHANCES WILL REMAIN QUITE HIGH...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA. HOWEVER...BY SATURDAY...THE JET AXIS STARTS TO SLINK EASTWARD...RESULTING IN AN IMPROVEMENT OF CONDITIONS FROM WEST TO EAST DURING THE DAY. FRIES && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... HAVE SOME LINGERING POPS ALONG THE RIDGES INTO THE EVENING HOURS AS H500 TROUGH AXIS PULLS EAST ALONG WITH THE SURFACE WAVE. STILL...MOST IF NOT ALL EVENING FIREWORKS DISPLAYS SHOULD NOT SUFFER ANY WEATHER-RELATED IMPACTS. THEREAFTER...WHILE A MIDLEVEL LOW DRIFTS ACROSS THE OHIO VALLEY THROUGH SUNDAY NIGHT...WEAK RIDGING EXTENDS FROM THE MIDATLANTIC COAST TO LAKE ERIE IN RESPONSE. THIS WILL HELP TO KEEP LOW LEVEL MOISTURE SUPPRESSED TO THE SOUTH...AND HAVE CONTINUED THE DRY FORECAST THROUGH THE PERIOD. SOME HIGH CLOUDS WILL MANAGE TO FLOAT UP FROM THE SOUTH FROM TIME TO TIME. THE RISING HEIGHTS WILL PROMOTE WARMING TEMPERATURES...TO LEVELS AROUND SEASONAL LEVELS. TRANSITION TO A MORE ZONAL FLOW PATTERN BEGINS ON MONDAY AHEAD OF AN APPROACHING FRONT. THE WEAKENING RIDGE ALLOW MOISTURE TO RUN UP NORTH...ESPECIALLY IN AREAS EAST OF PIT. MODEL SOUNDINGS START TO LOOK MORE FAVORABLE FOR AT LEAST SCATTERED DIURNAL CONVECTION AS WELL. HAVE ADDED SOME LOW POPS AS A RESULT. ACTIVITY SHOULD DIE OFF MONDAY EVENING...BEFORE MORE GENERAL RAIN CHANCES ARRIVE WITH A TUESDAY FRONT. EXPECTING FURTHER WARMING TO ABOVE NORMAL HIGH TEMPS AREAWIDE BY MONDAY AFTERNOON. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE UPPER FLOW IS PROGGED TO FLATTEN THROUGH MUCH OF THE PERIOD. INDIVIDUAL SHORTWAVES IN THE FLOW ARE EXPECTED TO BRING PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. USED AN ENSEMBLE BASED WPC GUIDANCE TO SMOOTH OUT DIFFERENCES IN INDIVIDUAL MODELS...WITH DOWNWARD ADJUSTMENTS TO WPC POPS. SEASONALLY WARM TEMPERATURES ARE EXPECTED. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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AREA OF RAIN CONTINUES TO SLOWLY LIFT NORTHEASTWARD AS A WEAK SURFACE LOW APPROACHES. CONSIDERING THE SLOW SPEED OF THE PRECIPITATION AND UPPER LEVEL SUPPORT FOR A PERIOD OF MODERATE RAINFALL...IFR VISIBILITY RESTRICTIONS ARE ANTICIPATED. HAVE GENERALLY ADDRESSED THIS WITH TEMPO GROUPS BASED ON ESTIMATED SPEED AND HI RES MODEL DATA THROUGH TONIGHT. WHILE PROLONGED IFR VISIBILITIES IS NOT ANTICIPATED AT THIS TIME...LOW MVFR/IFR CIG RESTRICTIONS ARE LIKELY WITH THE LOW LEVELS SATURATED AND WEAK MIXING. BULK OF THE MOISTURE ASSOCIATED WITH THE LOW SHOULD BE EAST OF PIT BY 12Z AND EAST OF LBE SHORTLY AFTER. HIGH PRESSURE SHOULD BRING THE RETURN OF VFR CONDITIONS BY MIDDAY. WITH THE PASSAGE OF THE LOW TONIGHT EXPECT ESE TO NW WIND SHIFT. SPEED WILL STAY UNDER 10KTS. .OUTLOOK.../SATURDAY NIGHT THROUGH TUESDAY/... THE NEXT CHANCE OF RESTRICTIONS WILL COME WITH A FRONTAL SYSTEM ON TUESDAY OR TUESDAY NIGHT.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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