Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 122314 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 714 PM EDT SAT JUL 12 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL DRIFT EAST OFF THE MID ATLANTIC COAST THIS AFTERNOON...SETTING UP AN INCREASINGLY HUMID AIR FLOW FROM THE SOUTH. AN UNSETTLED WEATHER PATTERN WILL DEVELOP ACROSS THE NORTHWEST PART OF THE STATE LATE TONIGHT...BEFORE SPREADING ACROSS THE ENTIRE REGION SUNDAY AND MONDAY AS A COLD FRONT PUSHES SOUTHEAST FROM THE GREAT LAKES. COOLER AND DRIER AIR WILL MOVE IN BEHIND THE COLD FRONT FOR THE MID TO LATE WEEK PERIOD. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... EXPECT MOSTLY SUNNY SKIES TO PREVAIL ACRS CENTRAL AND WESTERN SECTIONS OF THE CWA THROUGH THE AFTERNOON HOURS AS 3 DEG C OF WARMING ALOFT /4-5C AT 700 MB...INCREASING TO 7-8C BY LATE THIS AFTERNOON/ AND A RELATIVE MIN IN PWAT /AROUND 1.0 INCH/ SPREADS EAST OVER THE AREA...AND EFFECTIVELY CAPS OFF ANY CU PRIOR TO REACHING THE TCU STAGE. AN AREA OF ISOLD/SCATTERED SHOWERS AND A FEW LOW- TOPPED PULSE TSRA HAVE FORMED ACROSS THE SUSQ VALLEY AND NE MTNS...WHERE MID LEVEL TEMPS HAVE BEEN SLIGHTLY COOLER AND WHERE A NORTH/SOUTH RIBBON OF HIGHER PWAT AIR /AROUND 1.5 INCHES/ IS COLLOCATED. HAVE INCREASED THE POPS AND QPF BASED ON THE TIMING OF THE STORMS. THESE STORMS HAVE STRONG VILS AND HAVE HAD ALMOST 3 INCHES OF PRECIPITATION IN SOME AREAS IN EASTERN LEBANON COUNTY. MID TO LATE AFTERNOON TEMPS WILL PEAK IN THE LOWER 80S ACROSS THE NRN AND WRN MTNS...AND IN THE 85-87F RANGE ACROSS THE MID AND LOWER SUSQ VALLEY. A FAIRLY POTENT VORT MAX/SHORT WAVE TROUGH WILL PUSH EAST THROUGH THE LOWER LAKES LATE TONIGHT. SHRA/TSRA SHOULD APPROACH THE NWRN COUNTIES AS A 35-40KT SWRLY LLJET DEVELOPS IN OHIO AND SPREADS INTO NRN PA. WILL KEEP CONTINUITY WITH POPS INCREASING TONIGHT...WITH THE ARRIVAL OF SHOWERS/TSRA MAINLY AFTER 07Z SUNDAY. CLOUD COVER INCREASES OVERNIGHT...SO TEMPS WILL LIKELY NOT DROP TO NEAR NORMAL. EXPECT FAIRLY UNIFORM LOWS IN THE 60S. && .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 /23Z SATURDAY THROUGH THURSDAY/...
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MAINLY VFR CONDITIONS WILL PREVAIL FOR THE REGION TONIGHT. VCSH WILL REMAIN POSSIBLE AT KMDT AND KLNS FOR THE NEXT FEW HOURS. VSBY AND CIGS MAY BRIEFLY DROP TO MVFR AT THESE SITES....BUT DUE TO BREVITY AND UNCERTAINTY WILL LEAVE OUT FROM ACTUAL TAFS. MVFR FOG IS POSSIBLE ACROSS THE CENTRAL VALLEYS AND SUSQUEHANNA REGION TAF SITES EARLY SUNDAY MORNING. RESIDUAL MOISTURE FROM RAINFALL THIS 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 TOWARD DAWN SUNDAY. RA CHANCES WILL INCREASE FROM NW TO SE THROUGHOUT THE DAY...BUT MOST SITES WILL REMAIN 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.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...DANGELO/LAMBERT LONG TERM...DANGELO/CERU AVIATION...LAMBERT/COLBERT

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