Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 110142 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 942 PM EDT THU JUL 10 2014 .SYNOPSIS... A 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 ISOLATED SHOWERS AND THUNDERSTORMS INTO THE FIRST PART OF THE WEEKEND. A SERIES OF REINFORCING COLD FRONTS WILL PROVIDE SEVERAL OPPORTUNITIES FOR RAINFALL THROUGH EARLY NEXT WEEK...WHILE HELPING TO CARVE OUT A HIGHLY ANOMALOUS UPPER TROUGH AND BONAFIDE POLAR VORTEX ACROSS SOUTHEASTERN CANADA AND THE UPPER GREAT LAKES. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FAIRLY ACTIVE LATE AFTERNOON AND EVENING OF STORMS ACROSS CENTRAL AND SOUTHEAST PORTIONS OF CENTRAL PA. A FEW HAILERS EARLY ON WERE FOLLOWS BY SLOW MOVING STORMS WITH HEAVY DOWNPOURS...AND ISOLATED AREAS OF WIND DAMAGE...AS UPPER TROF AXIS SWINGS INTO WESTERN PA. LINGERING ACTIVITY IS WEAKENING AND WILL EXIT MY SOUTHERN AND SOUTHEASTERN COUNTIES WITHIN THE NEXT HOUR OR SO. HIGH PRESSURE WILL DOMINATE OVERNIGHT WITH CLEARING AND PATCHY VALLEY FOG DEVELOPING INTO EARLY FRIDAY MORNING. MINS WILL RANGE FROM THE LOWER 50S NORTH TO THE MID 60S SOUTHEAST. && .SHORT TERM /6 AM FRIDAY MORNING 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 PWS AXIS. STILL CAN NOT RULE OUT AN ISOLD SHRA/TSTM DURING THE AFTN OVER ERN PORTIONS OF THE CWA BUT POPS WILL BE BARELY MENTIONABLE/AOB 20 PCT. TEMPS SHOULD EDGE A LITTLE WARMER THAN TODAY. STG WAA UPSTREAM OVER THE GRT LKS/OH VLY WILL LKLY BRING SOME MID-HIGH CLOUDS INTO WRN SXNS BY 12Z SAT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE AREA SHOULD BE IN MORE OF A RETURN FLOW REGIME BY SAT AS THE SFC HIGH SLIPS OFF THE EAST COAST. STILL CANT RULE OUT AN ISOLD SHRA/TSTM IN SPOTS WHILE MOST AREAS STAY DRY. STALLED FRONT ALONG THE SOUTHEAST 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/CYC FLOW 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. THE HIGHLY ANOMALOUS AMPLIFICATION OF THE LARGE SCALE PATTERN IS A VIRTUAL LOCK BY THE END OF THE PERIOD AS INDICATED BY ALL MEDIUM RANGE GLOBAL NUMERICAL MODELS AND ENSEMBLE SYSTEMS. THIS WELL- ADVERTISED HIGH MERIDIONAL EVENT WILL FEATURE 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 500MB 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 VERY HIGH FROM TUE-THU OF NEXT WEEK. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE SLOWLY EAST INTO THE LOWER SUSQUEHANNA VALLEY THROUGH 00Z. TERMINALS WILL REMAIN VFR UNLESS A STRAY STORM WANDERS INTO THE AIRSPACE...WHICH WOULD CAUSE CONDITIONS TO BRIEFLY CRASH TO IFR OR LOWER. MESO MODELS SUPPORT THE IDEA THAT THE CONVECTION WILL DIE OFF RAPIDLY AFTER SUNDOWN. CLEARING SKIES THIS EVENING AND A LIGHT WIND WILL PROMOTE PATCHY FOG LATER THIS EVENING AND OVERNIGHT...ESP WHERE RAIN FALLS OVER THE NEXT FEW HOURS. HIGH PRESSURE SHOULD SUPPORT WIDESPREAD VFR CONDS FRIDAY AND SAT WITH A LINGERING SLIGHT CHANCE OF AFTERNOON SHOWERS AND AREAS OF NIGHTTIME FOG...ESP OVER SRN AIRFIELDS. UPPER LOW MOVING INTO THE NORTHEAST LATE THIS WEEKEND WILL LEAD TO UNSETTLED CONDS. OUTLOOK... SAT...PATCHY AM FOG POSSIBLE. SUN-TUE...BRIEF...MAINLY PM...THUNDERSTORM IMPACTS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...DEVOIR/GARTNER SHORT TERM...GARTNER/STEINBUGL LONG TERM...RXR AVIATION...LA CORTE/GARTNER

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