Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210921 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 521 AM EDT THU AUG 21 2014 .SYNOPSIS...
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A WARM FRONT WILL PIVOT INTO CENTRAL PENNSYLVANIA THROUGH TONIGHT. UPPER TROUGHING MOVING EAST FROM THE GREAT LAKES ACROSS THE NORTHEAST STATES INTO THE CANADIAN MARITIME REGION WILL PUSH THE FRONT BACK TO THE SOUTH ALONG THE EAST COAST THIS WEEKEND...ALLOWING A LARGE AREA OF HIGH PRESSURE OVER NORTHERN NEW ENGLAND TO RIDGE SOUTHWEST ALONG THE EAST-SIDE OF THE APPALACHIANS THROUGH EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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WET GROUND...LGT WINDS AND M/CLR SKIES WILL CONTINUE TO SUPPORT LCL FOG/STRATUS DEVELOPMENT EARLY THIS MORNING. IT WILL BE A MUGGY AND HUMID START TO THE DAY WITH TEMPS/DWPTS IN THE LOW-MID 60S. RETURNS ON THE RADAR SCOPE ARE VERY ISOLATED AND SHOULD STAY THAT WAY THRU MID-LATE MORNING PER 00Z MESO MODEL CONSENSUS. A BROAD ZONE OF WNW FLOW ALOFT WILL PERSIST AGAIN OVER THE NORTHERN MID ATLANTIC STATES AS WEAKENING UPPER LOW SHIFTS EWD FROM THE GREAT LAKES INTO NEW ENGLAND BY 12Z FRI. ALTHOUGH THE HIGHEST PWS ARE PROGGED TO THE NORTH AND SW OF THE AREA TODAY OVER UPSTATE NY AND THE OHIO VALLEY...MULTIPLE FACTORS SHOULD AID IN THE DEVELOPMENT OF ISOLD TO SCT PM SHWRS/TSTMS INCLUDING ADDNL S/WV ENERGY ROUNDING THE SRN PERIPHERY OF UPPER LEVEL TROUGH PASSING TO THE NORTH...A MOIST/MODESTLY UNSTABLE AIRMASS AND RELATIVELY STEEP MID LVL LAPSE RATES. HIGHEST POPS /40-60%/ ARE DURING PEAK HEATING IN THE 18-00Z TIME WINDOW WHICH IS SUPPORTED BY THE SSEO/WRF/RAP/HRRR. WHILE THE NEAR TERM GUIDANCE SHOWS DECREASING CONVECTIVE CVRG TONIGHT...WILL NEED TO WATCH UPSTREAM FOR ORGANIZED "RING OF FIRE" CONVECTION DROPPING SEWD ALONG WARM FRONTAL ZONE DRAPED OVER THE UPPER OH VLY. A BLEND OF THE 00Z HIRES MODEL QPF SUGGESTS THE MAIN PCPN AXIS STAYS TO THE W/SW OF THE AREA FROM THE SRN GRT LKS ACRS OH INTO WV.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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UPPER LOW WILL BE PASSING INTO NEW ENG BY FRI MORNING. HOWEVER..SHORT TERM MDL DATA ALL TRACKING A TRAILING SHORTWAVE SEWRD THRU CENTRAL PA FRIDAY PM...WHICH WILL LIKELY BRING ANOTHER ROUND OF SHRA/TSRA TO THE AREA. HIGHEST /LIKELY/ POPS PLACED ALONG AND SW OF QUASI-STATIONARY FRONT...WHICH MDLS PLACE ROUGHLY FROM KBFD SE TO KTHV. SOUTH AND WEST OF THIS BNDRY...UNSTABLE SOUNDINGS AND HIGH PWATS COULD RESULT IN LOCALLY HVY RAINFALL IN TSRA. CONVECTION- ALLOWING MDLS PRODUCING ISOLATED SPOTS AMTS OF ARND 4 INCHES. HOWEVER...AVERAGE AMTS BASED ON BLENDED QPF SHOULD BE LESS THAN A HALF INCH. GEFS 925 TEMPS ARE SUPPORTIVE OF MAX TEMPS NR SEASONAL LEVELS FRIDAY. CONVECTION SHOULD DIMINISH AND PUSH SOUTH OF THE STATE FRIDAY NIGHT...AS SHORTWAVE DIVES SOUTH OF THE AREA. BEHIND THIS FEATURE...BACKDOOR COLD FRONT IS PROGGED TO WORK SWRD THRU CENTRAL PA FRI NIGHT. MOIST EASTERLY FLOW ASCENDING THE APPALACHIANS MAY PRODUCE LOW CLOUDS AND SPOTTY DRIZZLE LATE FRIDAY NIGHT.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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LARGE SFC HIGH OVR NEW ENG WILL BE THE PRIMARY DRIVER OF OUR WX THRU MOST OF THE EXTENDED FCST. MOIST...EASTERLY FLOW OFF THE ATLANTIC WILL LIKELY PRODUCE A DULL AND COOL SATURDAY...WITH AM LOW CLOUDS GIVING WAY TO A BIT OF BRIGHTENING BY AFTN. GEFS 925 TEMPS OF ONLY 16C-18C IMPLY MAX TEMPS FROM JUST THE U60S OVR THE HIGH TERRAIN OF THE CENTRAL MTNS...TO THE M70S OVR THE SUSQ VALLEY. MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON SUNDAY...BUT STILL REMAIN BLW NORMAL. EARLIER CONCERNS OF CENTRAL PA DEALING WITH RING OF FIRE CONVECTION APPEAR TO BE WANING...AS LARGE SCALE SUBSIDENCE AND DRY AIR ARE THE THEMES OF THE MED RANGE GUIDANCE EARLY NEXT WEEK BENEATH SFC RIDGE ALONG THE E COAST. FCST CONFIDENCE BEGINS LOWER BY THE MIDDLE OF NEXT WEEK...WHEN MED RANGE MDLS BEGIN TO DIVERGE. GEFS KEEPS RIDGE AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A WEAK COLD FRONT COULD PUSH SE INTO THE REGION. THUS...HAVE ADDED A LOW CHC OF TSRA WED. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV NORMAL BY WED.
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&& .AVIATION /08Z 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...STEINBUGL SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...STEINBUGL

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