Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210907 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 507 AM EDT SUN SEP 21 2014 .SYNOPSIS... A COLD FRONT WILL PASS THROUGH LATER TODAY. A LARGE AREA OF HIGH PRESSURE WILL BUILD OUT OF CENTRAL CANADA AND PROVIDE GENERALLY FAIR AND COOL WEATHER FOR MOST IF NOT ALL OF THIS WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOW CRUD CREEPING UP THROUGH THE ERN COS AND MOSTLY MID CLOUDS RIDING OVER THE WEST AND NORTH. BUT THE MOISTURE IS GETTING DEEPER OVER OHIO. EACH MINOR WAVE OF SHOWERS REACHES A LITTLE FARTHER INTO PA...AND IT LOOKS LIKE THIS NEXT PUSH ALONG A PRE- FRONTAL TROUGH WILL FINALLY MAKE MEASURABLE PRECIP OVER THE NWRN MOUNTAINS BY 9 AM. THE SHOWERS ARE BUTTING INTO THE UPPER RIDGING BUT THE TROUGH CONTINUES TO DIG AS IT SWINGS IN FROM THE WEST. MOST MODELS DEPICT THE STRUGGLE/DISSIPATION OF THE SHOWERS AS THE FORCING TRIES TO CROSS THE CWA...MOST LIKELY DUE TO LACK OF MOISTURE AND WARMER MID-LEVEL TEMPS. CAPPING SEEMS LIKE A GOOD ANSWER TO THE LACK OF CONVECTION IN THE LATEST/06Z NAM RUN...AS THE DEPTH OF THE CLOUDS SEEM LIMITED TO NOT MORE THAN 10KFT. WILL HOLD THE COURSE WITH GENERALLY LIKELY TO 80PCT POPS FOR SOME PERIOD OF THE DAY OVER MUCH OF THE CWA. HOWEVER...IT MAY TAKE A FEW MORE WAVES OF UPPER FORCING TO PUSH SHOWERS THE ENTIRE WAY ACROSS THE AREA. THE REAL FRONT/DRY AIR SEEMS LIKE IT WILL BE PASSING THROUGH IN THE AFTN WEST...LATE AFTN CENTRAL AND AROUND SUNSET OR JUST AFTER IN THE EAST. THE BEST LIFT WILL BE ALONG THE FRONT - SO WILL ALSO HOLD THE MENTION OF THUNDER INTO THE EVENING IN THE EAST. TEMPS HAVE A CHANCE TO GET ABOVE 80F AGAIN IN THE SE - BUT EARLY LOW CLOUDS AND SOME FOG COULD BUST THAT FORECAST. THE CLOUDS ARE SHALLOW THOUGH...AND WINDS WILL BE INCREASING FROM THE SSW...WHICH IS A NORMALLY-DRYING INFLUENCE - ESP IN THE EASTERN CWA. SPC STILL MENTIONS THE REGION IN SEE TEXT FOR DAY 1 OUTLOOK OF SEVERE WX. PLUSES FOR ISOLD SVR GUSTS ARE THE WELL-ALIGNED WINDS AND GENERAL INCREASE IN SPEED SHEAR THROUGH THE LOWEST 20KFT. KNOCKS AGAINST SVR WILL BE THE OVERALL LACK OF MOISTURE AND INSTABILITY AND THE LACK OF 50KT WINDS BELOW 15KFT. WILL STILL MENTION THE POSS OF ISOLD SVR GUSTS IN THE HWO...BUT CONFIDENCE IS MODERATE TO HIGH FOR A MINIMAL OR EVEN NIL SVR THREAT TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... AFTER THE FRONT PUSHES THROUGH...THE WINDS OUT OF THE WNW WILL LEAD TO A TYPICAL POST-FRONTAL SET-UP...AND THE RESIDUAL AND LAKE MOISTURE ASCENDING THE MTNS AND COLD AIR MOVING IN ALOFT WILL GENERATE INSTABILITY AND SCT SHRA FOR THE NWRN THIRD OF THE AREA TONIGHT AND PERHAPS THROUGH MID MORNING ON MONDAY. 8H TEMPS DO DIP INTO THE LOWER SINGLE DIGITS MONDAY AND MAXES MAY BE LIMITED TO THE M50S IN THE MTNS BUT STILL GET CLOSE TO 70F IN THE DOWNSLOPE- WARMED SOUTHEASTERN PIEDMONT. && .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 /09Z SUNDAY THROUGH THURSDAY/... SEVERAL WEATHER SYSTEMS DICTATING FLYING CONDITIONS ACROSS THE REGION THIS EVENING. APPROACHING FRONT FROM THE WEST PRODUCING A SOUTHWEST FLOW ACROSS CENTRAL AND WESTERN AREAS. IN THE MOUNTAINS OF THE WEST...UPSLOPE FLOW PRODUCING LOWERING CLOUDS...AND EXPECT MVFR CIGS TO DEVELOP OVERNIGHT. IN THE EAST...HIGH PRESSURE RIDGE PROVIDING IDEAL CONDITIONS FOR FOG AND LOW STRATUS TO DEVELOP. CENTRAL AIRFIELDS CAUGHT BETWEEN THESE SYSTEMS...AND MAY REMAIN VFR FOR MUCH OF THE OVERNIGHT. 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...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...GRUMM/CERU AVIATION...JUNG/FITZGERALD

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