Area Forecast Discussion
Issued by NWS State College, PA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KCTP 270723 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 323 AM EDT WED AUG 27 2014 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION TODAY AND PROVIDE A FOCUS FOR THUNDERSTORMS. HIGH PRESSURE WILL ARRIVE BEHIND THE FRONT AND BRING DRY WEATHER TO THE AREA THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... IR STLT LOOP SHOWS SCT MID-HIGH CLOUDS MOVG ACRS N-CNTRL PA WHILE SRN AREAS ARE CLR. VALLEY FOG IS STARTING TO DEVELOP AND SHOULD INCREASE IN CVRG OVER THE NEXT FEW HOURS TWD DAYBREAK. FOG WILL ERODE SHORTLY AFTER SUNRISE WITH LCL VISBYS IMPROVING TO 6SM+ BY 14Z. A LOW AMPLITUDE UPPER TROUGH OVER THE GREAT LAKES REGION THIS MORNING WILL TRANSLATE EWD INTO THE NORTHEAST STATES TONIGHT AND MOVE OFFSHORE DURING THE D2 PERIOD. AT THE SFC...A COLD FRONT ANALYZED FROM THE ST. LAWRENCE VLY SWWD BACK ACRS THE LWR LKS WILL PUSH SEWD ACRS CENTRAL PA THIS AFTN BEFORE SHIFTING SOUTH OF THE MASON DIXON LINE AFTER 00Z. THE GLOBAL MODELS ARE WELL CLUSTERED WITH THE UPPER TROUGH AND ASSOCIATED COLD FRONT CROSSING THE NORTHEAST...WITH A NON-NAM CONSENSUS SOLUTION PREFERRED BY WPC AS IT APPEARS TO BE STRONGER ALOFT AND A TAD SLOWER WITH THE ADVANCE OF THE SFC FRONT. THE MAIN FCST CONCERN IN THE NEAR TERM IS THE POTENTIAL FOR STRONG TO LOCALLY SVR STORMS THIS AFTN. MODELS ADVECT RICH BLYR MSTR EWD FROM THE OH VLY INTO CENTRAL PA IN ADVANCE OF THE SFC COLD FRONT...WITH 60-65F DEWPOINTS PROGGED BY THE CONSENSUS GUIDANCE. THE NAM IS LKLY TOO MOIST WITH LOW 70S DEWPOINTS. STRONG HEATING AND DESTABILIZATION WILL LEAD TO MU CAPES IN EXCESS OF 1000 J/KG ALONG A NARROW CORRIDOR PRECEDING THE COLD FRONT. THE LOW-MID LVL BACKGROUND WIND FIELDS WILL NOT BE PARTICULARLY STRONG...AND THE BEST DEEP SHEAR LAGS THE FRONT. HOWEVER...A FEW CELLS CAPABLE OF PRODUCING SMALL TO MARGINALLY SEVERE HAIL AND LOCALLY STRONG TO DMGG WIND GUSTS WILL BE POSSIBLE GIVEN COMBO OF "SUFFICIENT" SHEAR AND DECENT INSTABILITY. THE D1 SPC OUTLOOK PLACES THE ERN ZONES IN THE CATEGORICAL SEE TEXT WITH 5% SVR PROBS BUT COULD SEE AN ISOLD SVR STORM FURTHER WEST ACROSS S-CENTRAL PA TO THE LAUREL HIGHLANDS. CONVECTIVE ACTIVITY SHOULD WEAKEN QUICKLY WITH THE LOSS OF DAYTIME HEATING AND EVENTUALLY DISSIPATE/SHIFT S-SEWD AFTER MIDNIGHT. AFTERNOON TEMPS WILL APPROACH 90F FROM THE SCNTRL RIDGE/VALLEY REGION INTO THE LWR SUSQ VLY...WITH UPPER 70S TO LOW 80S COMMON IN THE NW/NCNTRL HIGH TERRAIN. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... HIGH PRESSURE AND MUCH DRIER AIR WITH LOW/COMFORTABLE HUMIDITY WILL OVERSPREAD THE AREA ON THURSDAY. ENS DATA SHOWS TEMPS ALOFT SLIGHTLY BLW NORMAL OVER NRN/NERN PA WHICH SHOULD PROMOTE AFTN CU/SC CLOUDS. TEMPS RANGE FROM AROUND 70F IN THE NW TO 80F IN THE SE. THU NGT LOOKS SEASONABLY COOL WITH VALLEY FOG PROBABLE UNDER SFC RIDGE WITH M/CLR SKIES AND NEARLY CALM WINDS. WAA CLOUDS MAY IMPACT MIN TEMP FCST BUT FOR NOW SEE NO REASON TO DEVIATE FROM CONSENSUS GUIDANCE. && .LONG TERM /FRIDAY THROUGH TUESDAY/... UPPER RIDGE IS FORECAST TO SURGE NWD ALONG THE EAST COAST INTO THE EARLY WEEKEND AS SHORTWAVE ENERGY SUPPORTING WEDNESDAY FROPA LIFTS OUT. THIS RIDGING...ACCOMPANIED BY HIGH PRESSURE SLIDING ACROSS NEW ENGLAND WILL BRING A RETURN TO DRY CONDITIONS FOR LATE THIS WEEK. AS THE HIGH MOVES OFF OF THE COAST RETURN SLOW WILL HELP PULL THE FRONT FROM EARLIER IN THE WEEK NORTHWARD INTO WESTERN PA ON SATURDAY. AFTERNOON HIGH TEMPS NEAR NORMAL ON FRIDAY WILL SURGE TO 5 TO 10 DEGREES ABOVE NORMAL OVER THE WEEKEND. NEXT SHORTWAVE TROF IN THE NORTHERN STREAM FLOW IS PROGGED TO EMERGE FROM THE PLAINS ON FRIDAY AND LIFT TO EASTERN ONTARIO BY SUNDAY. THIS WILL SUPPORT A COLD FRONT REACHING NRN PA ON SUNDAY. MODEL TRENDS HAVE BEEN TO SLOW THE ARRIVAL OF THE FRONT AND TO TALL THE SOUTHWARD PROGRESS OF THE FRONT AS SUPPORTING SHORTWAVE ENERGY SHEARS NEWD. CURRENT TIMING PLACES THE FRONT OVER NORTHWEST PA ON MONDAY WITH A SFC WAVE RIDING ALONG THE FRONT...AND THE FRONT LIFTING NORTH OF THE STATE BY TUESDAY. THIS SLOWER...LESS AGGRESSIVE SCENARIO WILL KEEP SCATTERED SHOWERS/TSRA IN THE FORECAST FOR THE WEEKEND...BUT IS LESS UNSETTLED FOR THE HOLIDAY WEEKEND THAN PREVIOUS THINKING. CLOUDY CONDS ON MONDAY WILL BRING MAX TEMPS BACK TO WITHIN A COUPLE DEGREES OF NORMAL AND BELOW NORMAL ON TUESDAY. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... HIGH CLOUDS WERE DRIFTING ACROSS THE NORTHERN MOUNTAINS OF PENN EARLY THIS MORNING...WHILE SKIES WERE CLEAR ACROSS THE SOUTHERN HALF OF THE STATE. LIGHT AND VARIABLE...TO LIGHT SOUTHWESTERLY WIND WAS NOTED AT ALL AIRFIELDS. A LAYER OF BKN...MAINLY VFR STRATO CU WILL SLIDE EAST INTO NWRN PENN DURING THE MID TO LATE MORNING HOURS AHEAD OF AN APPROACHING COLD FRONT /CURRENTLY STRETCHED FROM NEAR KTOL...TO KIAG/. CLOUD BASES AT KBFD AND KJST COULD DIP INTO THE MVFR RANGE AT TIMES LATER THIS MORNING AND EARLY THIS AFTERNOON. THE COLD FRONT WILL DRIFT SLOWLY SE AND CROSS CENTRAL PA AIRFIELDS DURING THE LATE AFTERNOON HOURS...BEFORE REACHING THE LOWER SUSQUEHANNA VALLEY /KMDT AND KLNS/ LATER THIS EVENING. INSTABILITY AND MOISTURE WILL BE QUITE HIGH AHEAD OF THE COLD FRONT...SO INCLUDED VCTS FOR ABOUT A 4-HOUR PERIOD PRECEDING THE FRONTAL PASSAGE. BRIEF MVFR CONDITIONS ARE POSSIBLE IN THE THUNDERSTORMS. MAINLY VFR IS EXPECTED TONIGHT INTO THURSDAY IN THE WAKE OF THE CFROPA. A 6-10 HOUR PERIOD OF NW WINDS AVERAGE 8-10 KTS...WITH GUSTS IN THE MID-UPPER TEENS IS EXPECTED LATE TODAY AND TONIGHT IN THE MDTLY TIGHT LLVL PRESSURE GRADIENT FOLLOWING THE COLD FRONT. OUTLOOK... THU-FRI...LATE NIGHT-EARLY MORNING RESTRICTIONS IN FOG POSSIBLE...OTHERWISE VFR. SAT-SUN...MAINLY VFR. CHC OF SHOWERS/ISOLD TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...LA CORTE/STEINBUGL LONG TERM...LAMBERT/GARTNER AVIATION...RXR/LAMBERT

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.