Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210646 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 246 AM EDT THU AUG 21 2014 .SYNOPSIS... AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS. WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS WILL RANGE FROM THE L/M60S ACROSS THE REGION. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/... THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS FORECAST TO DRIVE INTO THE OHIO VALLEY. LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO 1800JKG-1 RANGE SECOND HALF OF THE DAY. BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS. OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z TIMEFRAME. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE REGION. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... UPPER LEVEL S/WV CURRENTLY ROTATING ACROSS CENTRAL PA IS HELPING TO SUSTAIN ISOLD CONVECTION OVER THE AIRSPACE EARLY THIS MORNING. ONLY TERMINAL IMPACT ATTM APPEARS TO BE IPT WHICH SHOULD GET A -SHRA WITH A FEW LTG STRIKES NEARBY 07-08Z. HRRR/COSPA DATA SHOWS LINGERING SHOWERS DISSIPATING OR MOVG E THROUGH DAYBREAK. FOG AND LOW CLOUDS LKLY TO BE MORE OF A FACTOR EARLY THIS MORNING GIVEN RECENT RAIN/WET GROUND...LIGHT WINDS AND HIGH BOUNDARY LAYER MOISTURE/SFC DEWPOINTS IN THE 60S. CUT BACK ON EXTENT OF IFR CONDS FROM PREVIOUS FCST WITH HIGHEST CONFIDENCE AT TERMINALS THAT RECEIVED DECENT RAINFALL YESTERDAY. REDUCED CONDITIONS SHOULD IMPROVE TO VFR BY MID-LATE MORNING. A CONSENSUS OF HIRES MDL GUIDANCE INDICATES MORE DISORGANIZED/WDLY SCT SHRA AND TSTMS DEVELOPING THIS AFTN. WILL LKLY ADD SOME MENTION INTO 12Z TAFS BUT FOR NOW WENT WITH SCT-BKN 040-050. ANTICIPATE DECREASING CVRG OF SHRA AND TSTMS INTO THE LATE EVE/OVERNIGHT PERIOD WITH AREAS OF FOG/ST DEVELOPING AGAIN WITH SOME CLEARING/LGT WINDS/MOIST AIRMASS. OUTLOOK... FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...GRUMM LONG TERM...FITZGERALD/CERU AVIATION...STEINBUGL

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