Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210329 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1129 PM EDT WED AUG 20 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 THURSDAY MORNING/... STILL SOME WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ABOUT THE STATE TONIGHT CENTRAL AREAS. THERE IS ONE PERSISTENT AND SLOW TO DIE ORGANIZED AREA OF CONVECTION OVER ELK AND NORTHERN CLEARFIELD COUNTIES TONIGHT. IT IS MOVING SLOWLY TO THE SOUTH AND EAST. IT HAS HELD TOGETHER ON RADAR FOR HOURS AND COLD CLOUD AREA IMPLIES IT HAS SOME LIFE LEFT. LOW-LEVEL VELOCITY DATA IMPLIES IT HAS A COLD POOL WHICH WILL LIKELY ALLOW IT TO PERSIST FOR A FEW MORE HOURS. SO WE HAD TO KEEP RAIN AND POPS 80 TO 90 PERCENT UP THERE. THE HRRR SHOWS THIS SYSTEM SPLITTING AND GOING ACROSS CENTRAL PA THROUGH 0700 UTC. COULD SEE ISOLATED THUNDER AND RAIN AREAS IF THE 23Z HRRR IS CORRECT. MOST OTHER AREAS UNAFFECTED BY THIS CONVECTION SHOULD SEE FOG DEVELOP. PERHAPS PATCHY DENSE FOG IN AREAS. && .SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... 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. THE 13KM RAP FROM 0100 UTC SHOWS LITTLE OR NO RAINFALL OVERNIGHT AND ORGANIZED RAIN WELL TO OUR WEST IN MORNING HOURS. AN OPTIMISTIC ENSEMBLE OF TWO. 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 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 /04Z THURSDAY THROUGH MONDAY/... NOT A LOT OF CHANGE TO 03Z TAFS. EARLIER DISCUSSION BELOW. DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER SET. MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO THE REST OF THE AREA OVERNIGHT. MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS. FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT. FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD. OUTLOOK... FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...GRUMM SHORT TERM...GRUMM LONG TERM...FITZGERALD/CERU AVIATION...MARTIN/STEINBUGL

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