Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 130307 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1107 PM EDT SAT JUL 12 2014 .SYNOPSIS... HIGH PRESSURE WILL DRIFT EAST OFF THE MID ATLANTIC COAST SETTING UP AN INCREASINGLY HUMID AIR FLOW OVER THE REGION. A PAIR OF COLD FRONTS EARLY NEXT WEEK WILL EVENTUALLY USHER IN COOLER AND DRIER AIR FOR MIDWEEK. THE COOL CONDITIONS WILL LAST THROUGH LATE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... RADAR SHOWS ONE LONELY SHOWER JUST EAST OF WILLIAMSPORT...OTHERWISE IT`S DRY WITH JUST SOME THIN HIGH CLOUDINESS DRIFTING ACROSS. I USED THE LATEST HRRR AND NAM AND BACKED OFF ON THE TIMING OF THE SHOWERS EXPECTED TO MOVE INTO THE NWRN ZONES LATER TONIGHT. A POTENT SHORT WAVE IS HELPING ORGANIZE A LINE OF STORMS FROM WISCONSIN TO SOUTHERN MISSOURI. THIS WILL PUSH SHOWERS AND THUNDERSTORMS INTO NWRN ZONES AROUND OR SHORTLY AFTER SUNRISE. INCREASING HIGH CLOUDS OVERNIGHT WILL HELP KEEP MIN TEMPS ABOVE NORMAL...ONLY DROPPING INTO THE LOW TO MID 60S REGION-WIDE. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... SFC COLD FRONT WILL BE SLIDING GRADUALLY SE ACROSS THE GLAKES SUNDAY...REACHING A LINE FROM NEAR CYYZ TO KTOL TO KIND AROUND 00Z MONDAY. REMNANT MID AND HIGH CLOUDS ARE EXPECTED FOR THE MORNING/MIDDAY HOURS SUNDAY...FROM THE POTENTIAL UPSTREAM MCS. SCATTERED SHRA/ISOLATED TSRA WILL DRIFT QUICKLY EAST /AT 35-40 KTS/ ACROSS THE NORTHERN MTNS BETWEEN 12-16 SUNDAY. AFTERWARD...A COMPLEX CLOUD/LLVL HEATING PATTERN WITH SEVERAL OUTFLOW BOUNDARIES WILL FIRE OFF NEW /AND LOCALLY STRONG TO SVR TSRA/ AS MEAN SFC BASED CAPES VIA THE SREF RAMP UP TO BETWEEN 1000-1500 J/KG...WITH POCKETS OF LOCALLY HIGHER INSTABILITY NEAR 2500 J/KG /VIA THE 12Z NAM/. WHAT SIGNIFICANT POCKETS OF HIGHER CAPES CAN DEVELOP...THEY/LL HAVE THE OPPORTUNITY TO COMBINE WITH MODERATELY STRONG SPEED AND DIRECTIONAL SHEAR TO CREATE EHI/S OF 1.5-2.5 M2/S2. SPC ALSO NOTES THAT MODEL HODOGRAPHS FAVOR BOWING LINE SEGMENTS AND EVEN A FEW SUPERCELLS/BRIEF TORNADOES ACROSS THE CWA. THEIR DAY 2 SLIGHT RISK AREA FOR SUNDAY COVERS A LITTLE MORE THAN THE SE HALF OF PENN. THERE SHOULD BE 2-3 PRIMARY AREAS OF CONVECTION...THE FIRST BEING DEVELOPING ACROSS CENTRAL/NRN PENN INVOF OF OUTFLOW BOUNDARIES...THE SECOND NEAR THE LEE TROUGH ACROSS THE CENTRAL MTNS AND SUSQ VALLEY...AND THE THIRD FORMING ACROSS THE WRN MTNS...ALONG AND AHEAD OF THE APPROACHING CFRONT. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE FOCUS FOR THE BEST CONVERGENCE SHIFTS SLOWLY EAST ACROSS THE AREA SUNDAY NIGHT AND MONDAY. HEIGHT FALLS OF 10DAM ARE EXPECTED MONDAY AS A SIGNIFICANT TROUGH PUSHES FORCIBLY INTO THE NRN GREAT LAKES. SPC HAS MOST OF THE CWA /EXCEPT FOR THE FAR NW ZONES/ IN THE SLIGHT RISK AREA FOR MONDAY. THE STORMS BOTH SUNDAY AND MONDAY WILL BE MOVING PRETTY FAST FROM WEST TO EAST...BUT TRAINING IS POSSIBLE DUE TO THE E-W BAROCLINIC ZONE. PWATS INCREASE TO NEAR 2 INCHES ON MONDAY. THUS...SOME HEAVY RAIN AND PERHAPS LOCALIZED FLOODING ARE POSSIBLE. CURRENTLY...3HR FFG ACROSS THE REGION IS IN THE 2.5 TO 3.5 INCH RANGE...WHICH WILL TEMPER THE RISK OF FLASH FLOODING UNLESS SEVERAL TSRA CAN TRAIN OVER THE SAME LOCATIONS OVER THE SPAN OF JUST A FEW HOURS. SEVERAL ROUNDS OF SHOWERS/TSRA SHOULD LOWER THESE FFG VALUES BY MONDAY WHEN THE CFRONT MOVES THROUGH. WILL NOT MENTION FLOODING IN THE HWO YET...BUT WILL CONTINUE TO MENTION THE POSSIBILITY OF SEVERE TSRA MICROBURSTS. THE GFS AND NAM GUIDANCE IS MUCH QUICKER TO PUSH THE FRONT THROUGH...WITH THE ECMWF DEEPENING THE UPPER LEVEL TROUGH...THOUGH THE LATEST RUN HAS OPENED UP THE CLOSED LOW. HOWEVER THE GFS BRINGS IN THE DRIER AIR THROUGH QUICKER...KEEPING ALL BUT THE ERN THIRD OF THE AREA DRY ON TUESDAY. THE EC DEVELOPS A COHERENT SFC LOW OVER THE MID MS VALLEY AND MOVES IT TO OUR W/N ON TUESDAY AS IT DEEPENS TO NEAR 1003MB. WILL THEREFORE KEEP ON WITH MENTIONS OF SHRA/TSRA FOR THE ENTIRE SHORT TERM PERIOD. HIGH AMPLITUDE RIDGE/TROUGH PATTERN DEVELOPS ACROSS THE MUCH OF NORTH AMERICA BEGINNING LATE IN THE WEEKEND...AND CONTINUES THROUGH THE FIRST HALF OF NEXT WEEK. THE BRUNT OF THE GREATEST 850-700 MB TEMP ANOMALIES AND ASSOCIATED BELOW NORMAL 500 MB HEIGHTS WILL BE AIMED AT THE LOWER OHIO VALLEY AND MID MISS VALLEY TUESDAY AND WEDNESDAY...WITH OUR REGION RESIDING ON THE ACTIVE/EASTERN SIDE OF THIS SLOW MOVING FEATURE. AS ADDITIONAL ENERGY IS DRIVEN SSE INTO THE BACK SIDE OF THE HIGH AMPLITUDE MIDWEST TROUGH...PROLONGED HIGH PWAT AIR /AND LIFT BENEATH THE RIGHT ENTRANCE REGION OF AN UPPER JET/ MAY LINGER ACROSS THE SERN ZONES WITH SCATTERED...MAINLY AFTERNOON TSRA WEDNESDAY AFTERNOON. THE PATTERN OVER THE NRN CONUS AND SRN CANADA APPEARS TO DE- AMPLIFY LATER NEXT WEEK AS THE EASTERN U.S. TROUGH BEGINS TO SHEAR OUT TO THE NE. THE DRIEST PERIOD OF THE LONG TERM WILL BE THURSDAY AND FRIDAY...THOUGH SOME ISOLATED CONVECTION STILL CANT BE RULED OUT EITHER OF THOSE TWO DAYS. TEMPS START OUT AOA NORMAL PRECEDING THE CFROPA NEXT SUNDAY...AND PERHAPS MONDAY ACROSS THE SE ZONES...THEN COOL TO AT LEAST 4-6F BELOW NORMAL FOR DAYTIME HIGHS TUESDAY THROUGH THURSDAY. TEMPS WILL LIKELY REBOUND TO NEAR NORMAL LATE NEXT WEEK. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... MAINLY VFR CONDITIONS...CLEAR SKIES AND CALM WINDS...WILL PREVAIL ACROSS PENNSYLVANIA TONIGHT. MVFR FOG IS POSSIBLE ACROSS THE CENTRAL VALLEYS AND SUSQUEHANNA REGION TAF SITES EARLY SUNDAY MORNING. RESIDUAL MOISTURE FROM RAINFALL SATURDAY EVENING WILL AID IN FOG FORMATION AT KMDT AND KLNS. AN APPROACHING WARM FRONT WILL BRING THE CHANCE OF TSRA IMPACTS TO THE NW MTNS SUNDAY. RA CHANCES AND CLOUD COVER WILL INCREASE FROM NW TO SE THROUGHOUT THE DAY...BUT SITES WILL REMAIN MAINLY VFR THROUGH THE TAF PERIOD. BRIEF REDUCTIONS IN VSBY AND CIGS ARE POSSIBLE TOMORROW AFTERNOON IN THUNDERSTORMS. OUTLOOK... SUN...BRIEF THUNDERSTORM IMPACTS POSSIBLE. SUN NIGHT-MON NIGHT...NUMEROUS SHOWERS/TSRA WITH MAINLY BRIEF PERIODS OF IFR TO MVFR. TUES-WED...THUNDERSTORM IMPACTS POSSIBLE...MAINLY IN THE AFTERNOON. THU...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...DANGELO/LAMBERT LONG TERM...DANGELO/CERU AVIATION...LAMBERT/COLBERT

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