Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 212157 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 557 PM EDT MON JUL 21 2014 .SYNOPSIS... A WEAKENING UPPER LEVEL TROUGH WILL SLIDE ACROSS PENNSYLVANIA TODAY. A COLD FRONT WILL MOVE SOUTHEAST FROM THE GREAT LAKES AND CROSS THE COMMONWEALTH LATE WEDNESDAY AND WEDNESDAY NIGHT. A REFRESHINGLY COOLER AND LESS HUMID AIRMASS WILL OVERSPREAD THE COMMONWEALTH FOR THE END OF THE WEEK INTO THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... REGIONAL RADAR LOOP SHOWING ISOLD CONVECTION DEVELOPING AS OF 21Z...PRIMARILY ACROSS THE LAUREL HIGHLANDS WHERE SPC MESOANALYSIS ESTIMATES CAPES APPROACHING 2000 J/KG. ELEVATED HEAT SOURCE OF THE ALLEGHENIES WILL BE THE PRIMARY FORCING MECHANISM THIS EVENING...AS LG SCALE FORCING VERY WEAK. HAVE BUMPED POPS UP SLIGHTLY ACROSS THE LAURELS/SC MTNS. OTHERWISE...STILL LIKE THE IDEA OF JUST SOME ISOLATED SHOWERS POPPING UP OVR THE CENTRAL/NORTHERN MTNS WHERE INSTABILITY IS RATHER MODEST. WEAK WINDS ALOFT WILL MEAN ANY SHRA/TSRA WILL BE SLOW-MOVING AND COULD PRODUCE SPOT AMTS IN EXCESS OF AN INCH. ACROSS THE LOWER SUSQ VALLEY...PERSISTENT MID LVL CLOUDINESS SHOULD LIMIT ANY CONVECTION RISK AND RESULT IN A DRY EVENING. SCT PULSE-TYPE CONVECTION OVR THE MTNS SHOULD DIE SHORTLY AFTER SUNSET. THE REST OF THE NIGHT SHOULD BE FAIR AND A BIT ON THE MUGGY SIDE. A NEARLY CALM WIND AND DIMINISHING CU SHOULD ALLOW TEMPS TO FALL CLOSE TO LATE AFTN DWPTS...PROMOTING AREAS OF FOG LATE TONIGHT. && .SHORT TERM /TUESDAY NIGHT THROUGH 6 PM TUESDAY/... TUESDAY WILL BE NOTICEABLY WARMER AND MORE HUMID WITH PARTLY SUNNY SKIES. ONCE AGAIN WE WILL BE DEALING WITH THE POTENTIAL FOR SOME DIURNAL CONVECTION. CAPES FCST IN THE 1000-1500J RANGE WILL BE BATTLING INCREASINGLY WARM MID LEVELS TRYING TO CREATE AFTERNOON SHOWERS AND T-STORMS. RIGHT NOW WE HAVE 20 POPS FOR THE AFTERNOON...I AM STILL DEBATING DROPPING THAT ALREADY SMALL NUMBER EVEN FURTHER GIVEN THE EXPECTATIONS OF THE WARMTH ALOFT PUTTING A LID ON MOST ACTIVITY. HIGH TEMPS TUESDAY WILL HAVE A REAL SUMMERY FEEL IN THE LOWER 80S ACROSS THE MTNS...AND MID TO UPPER 80S THROUGHOUT THE VALLEYS OF CENTRAL AND SOUTHERN PA. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... OVERALL SCENARIO REMAINS UNCHANGED IN THE LONG TERM PERIOD AS A LARGE UPPER RIDGE BUILDING OVER THE FOUR CORNERS REGION IS FORECAST TO EXPAND NORTH AND EAST INTO THE ROCKIES AND PLAINS DURING THE PERIOD. DOWNSTREAM...THIS WILL LEAD TO LONG WAVE TROFFING OVER THE EASTERN THIRD OF THE COUNTRY. UPPER LOW TO THE EAST OF HUDSON BAY WILL BE STRENGTHENED AT TIMES BY SHORTWAVE ENERGY IN THE STRONGER JET STREAM FLOW ACROSS CANADA. SOUTHWARD EXTENSION OF THIS LOW/TROF WILL AT TIMES DURING THE PERIOD STRENGTHENING THE TROFFING ACROSS THE NORTHEASTERN U.S./OUR REGION. TODAYS TREND OF MEDIUM RANGE MODEL GUIDANCE IS FOR STRONGER/DEEPER TROFFING DOWNSTREAM ACROSS THE EASTERN U.S...DEVELOPING AN ALMOST FULL LATITUDE TROF EXTENDING FROM THE EASTERN CANADA LOW SWD TO FLORIDA. THIS WILL LIKELY SERVE TO EXPAND AND PROLONG THE CHANCES FOR PCPN THIS WEEKEND. GUIDANCE FORECASTS CONTINUE TO BRING A FRONT AND INCREASED CHANGES FOR PRECIPITATION TOWARD PA IN THE WEDNESDAY/THURSDAY TIME FRAME AND SHOW A SECOND...POTENTIALLY STRONGER SYSTEM LATE NEXT WEEKEND. THE TREND OF STRONGER TROUGHING MENTIONED ABOVE HAS LEAD TO SLOWER ARRIVAL AND DEPARTURE OF THE FRONTAL SYSTEM IN THE DAILY PROGS. A WARM FRONT WILL BE ON THE DOORSTEP OF PA SUNDAY MORNING...A BIT SLOWER THAN FORECAST YESTERDAY. HAVE THUS ADJUSTED POPS/TIME TO SUIT. ASSOCIATED COLD FRONT DOES NOT CROSS THE STATE TIL MONDAY AT THIS POINT...LEADING TO A POTENTIAL PROLONGED PERIOD OF SHOWERS AND THUNDERSTORMS. AT THIS TIME FRAME HOWEVER...A LOT WILL LIKELY CHANGE BEFORE WE REACH NEXT WEEKEND. SURFACE HIGH PRESSURE AXIS TO OUR EAST WILL KEEP GENERALLY FAIR WEATHER ACROSS PENNSYLVANIA THROUGH EARLY WEDNESDAY. A WARMING TREND WHICH BEGAN TODAY...WILL CONTINUE RIGHT THROUGH WED...WHEN TEMPS ARE EXPECTED REACH THEIR PEEK FOR THE WEEK IN THE IN THE UPPER 80S TO AROUND 90F IN THE SUSQ VALLEY...AND GENERALLY IN THE MID 80S ELSEWHERE. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... FEW SHOWERS NEAR BFD AND JST LATE THIS AFT. 21Z TAFS SENT. EARLIER DISCUSSION BELOW. LAST HOLDOUTS WITH MVFR CEILINGS ARE MY WESTERN TERMINALS...BUT THEY WILL LIFT TO VFR AROUND OR SHORTLY AFTER 18Z...AND CONTINUE INTO THE EVENING HOURS. A WEAK DISTURBANCE ALOFT COULD HELP TRIGGER AN ISOLATED SHOWER OR THUNDERSTORM...OTHERWISE FAIR CONDITIONS WILL CONTINUE UNTIL MORE PATCHY LOW CLOUDS AND FOG FORM ONCE AGAIN OVERNIGHT. TUESDAY LOOKS LIKE A VIRTUAL REPEAT OF TODAY WITH ANY RESTRICTED CONDITIONS IMPROVING DURING THE MORNING THROUGH MID DAY...ALONG WITH THE POSSIBILITY OF ISOLATED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. OUTLOOK... WED-THU...SLOW NW-SE MOVG COLD FRONT WILL LIKELY BRING REDUCED CONDITIONS ALONG WITH SCT SHOWERS AND THUNDERSTORMS. FRI-SAT...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...FITZGERALD/LA CORTE SHORT TERM...LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...LA CORTE/MARTIN

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