Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 100830 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 430 AM EDT THU JUL 10 2014 .SYNOPSIS... PERSISTENT UPPER LEVEL TROUGH OVER THE GREAT LAKES WILL DAMPEN AS IT CROSSES THE NEW ENGLAND STATES INTO THE WEEKEND...WITH A WEAKENING QUASI-STATIONARY FRONT TRAILING SOUTHWARD ALONG THE MID ATLANTIC COAST. DESPITE THE INFLUENCE OF HIGH PRESSURE AT THE SURFACE...THE AREA WILL REMAIN VULNERABLE TO MAINLY ISOLATED SHOWERS AND THUNDERSTORMS INTO THE FIRST PART OF THE WEEKEND. A SERIES OF REINFORCING FRONTS PROVIDE SEVERAL OPPORTUNITIES FOR RAIN THE MIDDLE OF NEXT WEEK...WHILE HELPING TO CARVE OUT A BONAFIDE POLAR VORTEX OVER SOUTHEASTERN CANADA AND THE UPPER GREAT LAKES. && .NEAR TERM /THROUGH TONIGHT/... DWINDLING SHRA CONTINUE TO RIDE ALONG DYING SECONDARY COLD FRONT ACROSS THE N MTNS EARLY THIS MORNING. LATEST RAP SUGGESTS THESE SHOWERS DISAPPEAR TOWARD DAWN...AS BLYR CONTINUES TO COOL/STABILIZE. ELSEWHERE...MCLEAR SKIES AND A LIGHT WIND HAVE RESULTED IN PATCHY FOG. 11-3.9U IMAGERY INDICATES THE MOST EXTENSIVE FOG/LOW CLOUDS ARE ACROSS THE NW MTNS. ANY FOG AND LOW CLOUDS WILL BURN OFF SHORTLY AFTER DAWN...GIVING WAY TO M/SUNNY START TO THE DAY OVER MOST OF CENTRAL PA. HOWEVER...AN UPPER LEVEL TROUGH MOVG EWD ACRS THE LOWER GRT LKS...COMBINED WITH WEAK INSTABILITY...SHOULD BE ENOUGH TO GENERATE SCT SHRA/TSRA DURING THE AFTN...MAINLY ACRS THE SCNTRL MTNS. 8H TEMPS BTWN 12-14C SHOULD TRANSLATE TO HIGHS FROM THE M70S OVR THE HIGHEST TERRAIN OF THE ALLEGHENIES...TO THE M80S ACROSS THE LOWER SUSQ VALLEY. A SHOWER OR TWO MAY LINGER OVER THE SERN ZONES LATE THIS EVE...BUT HIGH PRES WILL DOMINATE FOR THE MOST PART WITH CLEARING AND PATCHY VALLEY FOG DEVELOPING OVERNIGHT AND INTO EARLY FRIDAY MORNING. GFS MOS APPEARS TOO COOL TONIGHT BASED ON BLEND OF ALL MDL SFC DWPTS. BCCONSALL APPEARS MUCH MORE REASONABLE...WITH LOWS RANGING FROM THE L50S OVR THE NW MTNS TO THE M60S OVR THE LOWER SUSQ VALLEY. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... VERY LITTLE CHANGE IN THE OVERALL PATTERN EXPECTED INTO DAY 2 WITH EVEN WEAKER FORCING ALOFT DUE TO DAMPENING OF UPPER TROUGH. EXPECT BULK OF PCPN TO REMAIN CONFINED TO ERN NC/VA TO THE DELMARVA NEAR Q-STNRY FRONT AND HI MSTR AXIS. STILL CANT RULE OUT AN ISOLD SHRA/TSTM DURING THE AFTN OVER ERN PRTNS OF THE CWA BUT POPS WILL BE BARELY MENTIONABLE/AOB 20 PCT. TEMPS SHOULD EDGE A LITTLE WARMER THAN THURSDAY. STG WAA UPSTREAM OVER THE GRT LKS/OH VLY SHOULD BRING SOME CLOUDS INTO WRN SXNS BY 12Z SAT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE AREA SHOULD BE IN MORE OF A RETURN FLOW REGIME BY SAT AS THE SFC HIGH SLIPS OFF THE EAST COAST. SIMILAR TO DAYS 1 AND 2..STILL CANT RULE OUT AN ISOLD SHRA/TSTM IN SPOTS WHILE MOST AREAS STAY DRY. STALLED FRONT ALONG THE EAST COAST SHOULD PIVOT BACK NWD AS WARM FRONT SAT NGT INTO EARLY SUNDAY WITH S-SWLY LLJ INC LLVL MSTR FLUX THRU THE UPPER OH VLY INTO WRN PA IN ADVANCE OF LEAD SHORTWAVE ENERGY AND ASSOCD SFC COLD FRONT MOVG SEWD ACRS THE GRT LKS-MIDWEST. AMPLIFICATION OF THE UPPER PATTERN BEGINS EARLY NEXT WEEK WITH A MODEL CONSENSUS GENERALLY INDICATING A FRONTAL PCPN AXIS SHIFTING SEWD THRU THE GRT LKS/OH VLY REGIONS INTO CENTRAL PA SUN-MON. ALTHOUGH PREDICTABILITY IS TOO LOW ATTM...A SEVERE WX THREAT SHOULD SPREAD SEWD IN TIME FROM THE UPPER MIDWEST/GRT LKS/OH VLY INTO THE MID ATLC AND NORTHEAST STATES...ALONG SRN PERIPHERY OF STRONGER WINDS ALOFT AND SEVERAL REINFORCING COLD FRONTAL SURGES ASSOCIATED WITH THE AMPLIFYING SYNOPTIC UPPER TROUGH. EACH COLD FRONTAL SURGE WILL PROVIDE AN OPPORTUNITY FOR SHOWERS/TSTMS THROUGH AT LEAST TUESDAY. A HIGHLY ANOMALOUS AMPLIFICATION OF THE UPPER PATTERN IS A VIRTUAL LOCK BY THE END OF THE PERIOD AS INDICATED BY ALL MEDIUM RANGE GLOBAL NUMERICAL MODELS AND ENSEMBLE SYSTEMS...FEATURING A FULL- LATITUDE RIDGE AND SEARING HEAT OUT WEST NOT BE BE OUTDONE BY THE RETURN OF THE POLAR VORTEX IN THE EAST OVER QUE/ONT AND THE UPPER GREAT LAKES. CONSIDERING THE MAGNITUDE OF THE UPPER LEVEL TROUGH WITH STANDARDIZED ANOMALIES ON THE ORDER OF -3 TO -4SD IN BOTH THE DETERMINISTIC GLOBAL MODELS AND THEIR RESPECTIVE ENSEMBLE MEANS...CONFIDENCE IN A PERIOD OF BELOW AVG TEMPS /DURING WHAT IS CLIMATOLOGICALLY THE HOTTEST TIME OF THE YEAR/ IS QUITE HIGH FROM TUE-THU OF NEXT WEEK. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... CENTRAL PA REMAINS IN A REGION OF RELATIVELY HIGH LOW-LVL MOISTURE TODAY...EVEN THOUGH STALLED COLD FRONT IS NOW EAST OF THE AREA. THE MAIN AVIATION CONCERN THIS MORNING WILL BE THE POSSIBILITY OF PATCHY FOG/LOW CIGS DUE TO RADIATIONAL COOLING. A COMBINATION OF 05Z DWPT DEPRESSIONS...CONDITIONAL CLIMATOLOGY AND LATEST RAP OUTPUT SUGGEST KBFD AND KIPT ARE MOST SUSCEPTIBLE TO A PERIOD OF IFR CONDS EARLY THIS MORNING. KIPT ALREADY HAS A 500FT CIG AT 05Z...BUT ARRIVAL OF MID LVL CLOUDS MAY BRIEFLY IMPROVE CONDS BTWN 06Z-08Z. ANY LOW CIGS/FOG SHOULD RAPIDLY MIX OUT BY 12Z...WITH PREDOMINATELY VFR CONDS EXPECTED FOR THE REST OF THE DAY. HOWEVER...A TROUGH OF LOW PRES APPROACHING FROM THE WEST WILL LIKELY TRIGGER SCT SHRA/TSRA DURING THE AFTN AND EVENING HRS. THE BEST CHANCE OF A BRIEF VIS REDUCTION WILL BE ACROSS THE SC MTNS...INCLUDING KJST AND KAOO. OUTLOOK... FRI-SAT...PATCHY AM FOG POSSIBLE. SUN-MON...BRIEF...MAINLY PM...THUNDERSTORM IMPACTS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD/STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...FITZGERALD

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