Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 041845 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 245 PM EDT FRI SEP 4 2015 .SYNOPSIS... ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO NEXT WEEK WITH GRADUALLY DECREASING HUMIDITY LEVELS. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE INTO EARLY THIS EVENING. HIGH PRESSURE WILL ENSURE FAIR AND DRY WEATHER FOR LABOR DAY WEEKEND. && .NEAR TERM /UNTIL 9 PM THIS EVENING/... ISOLATED SHOWERS AND THUNDERSTORMS AGAIN POPPING THIS AFTN AS EXPECTED...MAINLY ACROSS SRN PA. THIS WILL CONTINUE FOR THE NEXT SEVERAL HOURS WITH ANY SLOW MOVING STORMS PRODUCING BRIEF HEAVY DOWNPOURS. GUIDANCE INCLUDING LATEST HRRR IMAGERY SHOWS A CONVERGENCE OF ACTIVITY THROUGH THE LOWER SUSQ VALLEY SOUTH CENTRAL MTNS AS WEAK BACKDOOR COLD FRONT DROPS SOUTH...AND EASTERLY FLOW ON SRN END OF SFC HIGH CONCENTRATES MOISTURE WESTWARD INTO THE REGION. && .SHORT TERM /9 PM THIS EVENING THROUGH 6 PM SATURDAY/... CONVECTION ONGOING AT THE START OF THE PERIOD MAY BE THE LAST OF THE RAIN FOR A FEW DAYS. EXPECT SHRA/TSRA TO WANE THROUGH THE EVENING. THE INTERESTING/CHALLENGING PART OF THIS FORECAST MAY BE THE CLOUD COVER TONIGHT AND SAT MORNING AND RESULTANT MINS/MAXES. THE NAM IS PRETTY AGGRESSIVE IN ADVECTING LOW CRUD/STRATUS IN FROM THE EAST/SOUTHEAST TONIGHT AND PILING IT UP IN THE MOUNTAINS. HOWEVER...THE GFS IS NOT SO BULLISH ON THE LOW LEVEL MOISTURE. IT STILL MAKES LOWER CLOUDS /BELOW 8H/ BUT IS MORE NORTHEASTERLY WITH THE WINDS ON THE SRN PERIPHERY OF THE HIGH. THUS...MORE DRY AIR IS SEEN ADVECTING INTO THE AREA IN THE GFS SOLUTION. THIS ALLOWS THE MARITIME AIR/CLOUDS TO DRY OUT QUICKLY WITH MINIMAL MIXING. THE TROUBLE WITH THE DRIER SOLUTION IS THAT WE HAVE BEEN PRETTY MUGGY AND THE MDL OMEGA FIELDS DO NOT PORTRAY SOME OVERWHELMING DOWN- MOTION. IN FACT...THEY ARE PRETTY NEUTRAL. VERY ISOLATED DIURNAL CONVECTION IS POSSIBLE IN THE FAR WEST/SOUTHWEST ON SAT...BUT THE PWATS WILL BE MUCH LOWER - ONLY RANGING FROM 1 INCH IN THE NE TO 1.25 IN THE WEST. AT THIS POINT...THE MOST PROBABLE SOLUTION IN OUR WEAK FLOW IS THAT THE SFC HIGH STAYS UP OVER NEW ENGLAND AND THE DRY AIR MAKES ONLY SLOW PROGRESS TO MOVE ACROSS THE REGION. WILL KEEP IT MORE CLOUDY AND COOLER IN THE FIRST PART OF THE DAY AND KEEP MAXES SHORT OF GFS-MOS GUIDANCE. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... NOT MUCH TO CHANGE IN A SLOWLY EVOLVING EXTENDED FORECAST. HIGH PRESSURE SHOULD MAINTAIN DRY WEATHER SUNDAY-MONDAY. LEAD COLD FRONT ADVANCING EWD FROM THE GREAT LAKES/MIDWEST AND POTENTIAL ONSHORE FLOW MSTR MAY IMPACT THE FCST BY TUESDAY WITH SCT TSTMS POSS...BUT A CONSENSUS SOLUTION HOLDS BACK HIGHER POPS UNTIL WED OR MAYBE EVEN THU IN ASSOCIATION WITH A STRONGER SHORTWAVE/SFC COLD FRONT. SO TIMING DIFFS WILL NEED TO BE RESOLVED AS THE RIDGE SLOWLY BREAKS DOWN. THE GLOBAL NUMERICAL MODELS/ENSEMBLES ARE COMING INTO BETTER AGREEMENT ON A PATTERN CHANGE DURING THE SECOND HALF OF NEXT WEEK WITH A SHUFFLING OF THE LONGWAVE FLOW ALLOWING EWD PROGRESSION OF THE WESTERN TROUGH INTO THE CENTRAL STATES AND RECENT RIDGE OVER THE EASTERN UNITED STATES OFF THE COAST INTO THE WRN ATLC. THIS SHOULD EVENTUALLY BRING AN END TO THE RECENT HOT/DRY SPELL. A RETURN TO SEASONAL TEMPERATURES AND MORE ACTIVE PCPN PATTERN SEEMS PROBABLE BY NEXT WEEKEND IN THE NEW FLOW REGIME. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... GENERALLY VFR CONDS EXPECTED THROUGH EARLY EVENING HOURS...SAVE WHERE ISOLATED SHRA/TSRA MAY IMPACT AIRFIELDS...MAINLY ACROSS SOUTHERN PA. A BRIEF VIS REDUCTION IS POSSIBLE IN A FEW SPOTS FROM THESE STORMS...MAINLY THRU 05/01Z. A MOIST SERLY FLOW BEHIND THE COLD FRONT WILL LIKELY PRODUCE SOME LOW CIGS ACROSS THE MTNS OF CENTRAL PA TONIGHT AND EARLY SAT AM. SFC HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE WEEKEND. OUTLOOK... SAT...AM LOW CIGS POSS...MAINLY KBFD/KJST. SUN-TUE...PATCHY AM FOG POSS...MAINLY KBFD/KIPT. WED...COLD FROPA WITH SCT SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/GARTNER NEAR TERM...GARTNER SHORT TERM...DANGELO/GARTNER LONG TERM...RXR/STEINBUGL AVIATION...GARTNER

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