Issued by NWS State College, PA
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KCTP 221158 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 658 AM EST SUN NOV 22 2009 .SYNOPSIS... AN ANOMALOUS STRONG UPPER RIDGE WILL DOMINATE OUR WEATHER THROUGH MID-WEEK. THEN A SERIES OF WAVES WILL CARVE OUT A TROUGH OVER EASTERN NORTH AMERICA BEGINNING ABOUT THANKSGIVING. THE STRONG TROUGH WHICH DEVELOPS BY THE WEEKEND AND THE RIDGE OVER WESTERN NORTH AMERICA. IT WILL TURN COLDER AROUND THANKSGIVING. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 11-3.9 MICRON DATA SHOWS EXTENSIVE STRATOCU DECK OVR CENTRAL PA EARLY THIS MORNING...WHILE DOWNSLOPING NORTHERLY FLOW RESULTING IN CLEAR SKIES ACROSS THE LOWER SUSQ VALLEY. CLEAR SKY AND CALM WIND MAY RESULT IN PATCHY FOG OVR THE LOWER SUSQ EARLY TDY. LARGE SCALE SUBSIDENCE IN WAKE OF DEPARTING UPPER LVL SHORTWAVE SHOULD RESULT IN LOWERING INVERSION AND CLEARING SKIES LATER TODAY. LATEST NAM12/RUC13 SUGGEST FAIRLY RAPID CLEARING LATER THIS MORNING. HOWEVER...EASTERLY FLOW AND ASSOCIATED OROGRAPHIC UPLIFT OVR THE LAURELS COULD RESULT IN SLOWER CLEARING DOWN THERE. MODEL 900MB TEMPS SUPPORT A FAIRLY MILD DAY...GIVEN MSUNNY SKIES. HAVE LEANED TOWARD THE WARMER MAV GUIDANCE BASED ON THE 00Z NAEFS DATA...WHICH INDICATE HIGHS FROM NR 50F ALLEGHENIES...TO U50S SUSQ VALLEY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... AS SFC HIGH PUSHES OFF THE NEW ENG COAST...DEVELOPING MOIST...EASTERLY FLOW OVR THE MID ATLANTIC WILL LIKELY RESULT IN STRATOCU CREEPING NORTHWRD ALONG THE APPALACHIANS. THE NCEP ENSEMBLES SUGGEST THAT A BIT OF LGT RAIN/DZ MAY DEVELOP AS EARLY AS 12Z MONDAY OVR THE SC MTNS. HOWEVER...LATEST SREF INDICATES A BETTER CHC OF RAIN ACROSS SOUTHERN PA BY LATE MONDAY...AS EASTERLY WIND AND PWAT ANOMALIES SHIFT NORTH INTO PA. LG SCALE/QG FORCING REMAINS WEAK THROUGH MONDAY...SUPPORTING IDEA OF VERY LIGHT QPF. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HAVE INCREASED POPS FOR THE MON NITE/EARLY TUESDAY TIMEFRAME TO COINCIDE WITH PASSAGE OF SHORTWAVE AND ANOMALOUS PWATS. RIDGING AT SFC AND ALOFT SUPPORTS A LULL IN THE PRECIP TUE NITE. HOWEVER...A SERIES OF SHORTWAVES WILL BEGIN DIGGING OUT A DEEP TROF OVR THE MIDWEST DURING THE SECOND HALF OF THE WEEK. WED/THU APPEAR UNSETTLED/SHOWERY AHEAD OF THIS FEATURE. HOWEVER...EXACT TIMING OF TROF REMAINS UNCERTAIN...SO WILL KEEP POPS IN THE CHC CATEGORY FOR NOW. AS ANOMALOUS TROF MOVES OVR THE NORTHEAST CONUS...LAKE EFFECT SNOW SHWRS LOOKING MORE LIKELY FOR FRI/SAT. 500MB TRAJECTORIES SUGGEST LATE WEEK AIR MASS WILL BE A MIX OF PACIFIC AND POLAR...SO ONLY SEASONABLE CHILL EXPECTED. GEFS MEAN 850 TEMPS ARND -6C SUGGEST HIGHS FRI/SAT FROM U30S MTNS TO M40S SUSQ VALLEY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...-- Changed Discussion --MVFR/IFR STRATOCU DECK WILL HANG ON ACROSS MUCH OF CENTRAL PA /EXCEPT LOWER SUSQ/ THROUGH MID MORNING BEFORE RAPIDLY DIMINISHING. LOWER SUSQ WILL HAVE SHORT-LIVED LIGHT FOG THIS MORNING WITH A QUICK RETURN TO VFR CONDITIONS. FLOW TURNS SE THROUGH THE DAY AND EVENING...AND MOISTURE WILL QUICKLY RETURN OVERNIGHT IN THE FORM OF AN EXPANDING MVFR STRATOCU DECK FROM S TO N. BY 12Z CLOUDS WILL LIKELY LOWER TO IFR ACROSS SOUTHERN TIER. FORCING REMAINS LIGHT...BUT COULD EVEN SEE SOME PATCHY DRIZZLE /MAINLY AROUND KJST-KAOO/ BY 12Z. STARTING MONDAY...THE REGION WILL BE IN FOR AN EXTENDED PERIOD OF POOR FLYING CONDITIONS. OUTLOOK... MON...MVFR LCL IFR. PSBL SHRA IN THE AFTN. TUE...MVFR/IFR CIGS. SHRA IN THE AM. WED...MVFR TO VFR. THU...MVFR WITH CHC -SHRASN.-- End Changed Discussion --&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/MARTIN AVIATION...RXR
