Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210522 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 122 AM EDT SUN SEP 21 2014 .SYNOPSIS... FAIR WEATHER WILL CONTINUE OVERNIGHT AS HIGH PRESSURE MOVES EAST OF THE NEW ENGLAND COAST. A FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND A FEW THUNDERSTORMS SUNDAY. A LARGE AREA OF HIGH PRESSURE WILL BUILD OUT OF CENTRAL CANADA AND PROVIDE GENERALLY FAIR AND COOL WEATHER FOR MOST OF NEXT WEEK. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... SHOWERS STARTED TO DIMINISH AND BREAK UP OVER NERN OH...BUT JUST A FEW TINY SHRA HAVE POPPED UP IN OUR NWRN COS IN THE LAST HALF HOUR. THEY ARE SO SMALL AND QUICK MOVING THAT THE SPRINKLE FOR A LITERAL MINUTE THAT THEY GENERATE IS NOT WORTH PUTTING POPS IN FOR. HAVE ACTUALLY NUDGED POPS DOWNWARD A NOTCH OR TWO FOR THE OVERNIGHT AS THE BETTER FORCING DOES NOT REACH OUR NW UNTIL NEAR SUNRISE AND THE CLOUDS/SHOWERS IN ERIE RIGHT NOW ARE NOT EXPECTED TO INTENSIFY AS THEY MOVE INTO THE SLIGHTLY HIGHER HEIGHTS AND OVER DRIER AIR AT THE SFC. CLOUDS WILL THICKEN AND EXPAND - EVEN FROM THE SE WHERE LOW CRUD HAS BEGUN TO CREEP THRU LANCASTER CO. TEMPS WILL STAY VERY MILD FOR LATE SEPT. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM MONDAY/... DIGGING TROUGH TO THE WEST WILL PULL MOISTURE UP FROM THE MIDWEST AND AN ADVANCE TROUGH WILL TRY TO MAKE SHOWERS IN THE NWRN COS BY DAYBREAK ON SUNDAY. THE MAIN LOW AND UPPER TROUGH WILL BE OFFSET ENOUGH THAT THE PATTERN SHOULD REMAIN PROGRESSIVE AND THE MAIN COLD FRONT WILL PASS THROUGH SUNDAY EVENING. THE DEEP LAYER SHEAR AND SOME DECENT INSTABILITY IN THE LOW LEVELS COULD PRODUCE A FEW STRONGER STORMS AS THE FRONT MOVES THROUGH. QPF SEEMS RATHER PALTRY WITH PWATS BRIEFLY PEAKING AROUND 1.5 INCHES. ALL THE SHOWERS/STORMS SHOULD BE MOVING ALONG STEADILY. THE NAM CRANKS UP MORE SHOWERS IN THE POST- FRONTAL AIR...AND HAVE EXTENDED SCT POPS THROUGH THE NIGHT AND INTO MONDAY MORNING FOR THE WESTERN HIGHLANDS. THE 8H TEMPS DIP INTO THE +1-2C RANGE FOR A BRIEF TIME ON MONDAY OVER THE NW. MAX TEMPS WILL THEREFORE TAKE A TUMBLE ROM THE MID70S-L80S ON SUNDAY TO THE M50S- 70F ON MONDAY. THE LONG WAVE TROUGH WILL DEEPEN AS IT MOVES EASTWARD...BRINGING IN UNSTABLE NORTHWESTERLY FLOW...WHICH GIVEN THE FLOW ACROSS THE LAKE COULD ALLOW FOR SHOWERS TO CONTINUE ACROSS THE NW MTNS INTO MONDAY MORNING. THE LIMITING FACTOR ON MONDAY IS THE OVERALL LACK OF MOISTURE...WHICH WILL ALLOW FOR CLEARING SKIES. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE BUILDS IN AS THE LONG TERM IS BEGINNING AND IT SORT OF PARKS ITSELF OVER NEW YORK AND NEW ENGLAND WITH +2 TO +3 SIGMA ABOVE NORMAL MSLP ANOMALIES BY WEDNESDAY-THURSDAY. THE MODELS SEEM TO BE IN FAIR AGREEMENT SHOWING A BLOCKING 500 HPA ANTICYCLONE TO THE NORTHWEST AS A MASSIVE 500 HPA POSITIVE HEIGHT ANOMALY OF +2 TO +3 SIGMA DEVELOPS OVER CENTRAL CANADA BY THURSDAY AND INTO FRIDAY. THE MODELS AND EFS DO WELL FORECASTING ANTICYCLONES SO THERE SEEMS TO BE MORE OF A CONSENSUS. ON THE FAIR WEATHER FORECAST NEXT WEEK. EXPECT DIURNAL VALLEY FOG AND LOW CLOUDS LIKELY TO AFFECT THE REGION EACH MORNING ONCE THE BIG HIGH TAKES HOLD....AND CONTINUING DAILY INTO NEXT WEEKEND. THAT MASSIVE HIGH SHOULD CONTINUE THE DRY FAIR WEATHER THROUGH NEXT WEEKEND. TEMPERATURES ON MONDAY AND MONDAY EVENING WILL BE BELOW NORMAL...HOWEVER OUTSIDE OF MONDAY...TEMPERATURES THERE WILL BE A PERIOD OF NEAR NORMAL TEMPERATURES. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... WIDESPREAD VFR FLYING CONDS ACROSS CENTRAL PA AT 03Z. MAIN FORECAST CONCERN LATER TONIGHT WILL BE THE POTENTIAL OF DENSE FOG ACROSS EASTERN PA AND THE POSSIBILITY OF LOW CIGS AT KBFD TOWARD DAWN. CLEAR SKIES AND A LIGHT WIND BENEATH HIGH PRES RIDGE WILL PROMOTE AREAS OF FOG ACROSS EASTERN PA LATE TONIGHT AND SUNDAY MORNING. LATEST MDL GUIDANCE SUGGESTS IFR/LIFR VSBYS ARE LIKELY AT KLNS EARLY SUNDAY MORNING AND POSSIBLE AT KIPT AND KMDT. A MORE ACTIVE SOUTHERLY BREEZE SHOULD LIMIT THE FOG THREAT FURTHER WEST. HOWEVER...AN INCREASINGLY MOIST SOUTHERLY FLOW WORKING INTO THE NW MTNS COULD POTENTIALLY RESULT IN DEVELOPING IFR CIGS AT KBFD TOWARD DAWN. EARLY FOG WILL BURN OFF BY LATE AM ACROSS EASTERN PA. FOCUS WILL THEN SHIFT TOWARD COLD FRONT PUSHING SE ACROSS THE REGION. SHOWERS AND ISOLD TSRA ALONG COLD FRONT COULD PRODUCE A BRIEF VSBY REDUCTION AS THEY COME THRU ARND MIDDAY OVR THE CENTRAL MTNS AND DURING THE AFTN OVR EASTERN PA. HOWEVER...AFTER AN EARLY THREAT OF LOW CIGS AT KBFD...VFR CONDS SHOULD PREDOMINATE SUNDAY. OUTLOOK... MON...AM LOW CIGS POSS W MTNS. TUE...AM FOG POSS W MTNS. WED...AM FOG POSS...MAINLY NORTHERN PA. THU...PATCHY AM FOG POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...DANGELO/LA CORTE SHORT TERM...DANGELO/GARTNER LONG TERM...GRUMM/CERU AVIATION...FITZGERALD

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