Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 242050 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 450 PM EDT THU JUL 24 2014 .SYNOPSIS... HIGH PRESSURE AND A REFRESHINGLY COOLER AND LESS HUMID AIRMASS WILL PUSH SOUTHEAST FROM THE GREAT LAKES REGION TODAY AND STAY WITH US RIGHT INTO SATURDAY. A WARM FRONT WILL SLIDE EAST OUT OF THE OHIO VALLEY LATE SATURDAY FOLLOWED BY A WAVY...SLOW MOVING COLD FRONT FOR SUNDAY INTO SUNDAY NIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS WILL AFFECT CENTRAL PENNSYLVANIA AND THE ALLEGHENY PLATEAU SATURDAY NIGHT THROUGH SUNDAY NIGHT. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... COLD AIR ALOFT AND GOOD SOLAR HEATING GENERATED LOTS OF CU OVER THE ENTIRE REGION. THE WEAK/MODERATE SHORT WAVE TROUGH PASSING OVERHEAD WILL BE PUSHING TO THE S/E SOON AND DIURNAL HEATING ON IT/S WAY DOWN SOON AS WELL. CLOUDS ARE ALREADY ON THE DECREASE AT 18Z AS DRY AIR HAS MIXED WELL/DEEP. BY SUNSET A LOT OF THE CLOUDS WILL BE GONE...WITH THE GREATEST COVERAGE OVER THE SW/SC MOUNTAINS. EXPECT MOST OF THE AREA TO BECOME CLEAR AND ALLOW TEMPS TO DROP OFF THE CLIFF. BUF POINTED OUT THAT A GOOD SMOKE LAYER IS HEADING AT US /MAINLY TO THE N OF PA/ FROM CANADA. THIS MAY SERVE TO KEEP TEMPS UP JUST SLIGHTLY TONIGHT...BUT WILL WEIGHT THE FORECAST ONLY VERY SLIGHTLY TO ACCOUNT FOR THIS POSSIBLE EFFECT. MOS GUIDANCE RARELY PUMPS OUT RECORD MINS AT ANY POINT...SO WHEN 2 OF OUR CLIMO SITES ARE GUIDED TOWARD REC MINS...THAT IS A STRONG SIGNAL FOR A SIGNIFICANT EVENT. THE SET UP IS NEARLY-PERFECT. HIGH PRESSURE MOVES OVERHEAD. HOWEVER...THE HIGH PRESSURES AND 8H TEMPS ARE NOT HIGHLY ANOMALOUS - JUST SLIGHTLY BELOW NORMAL. THE WIND SHOULD DIE DOWN TONIGHT AND THE CLOUDS DISSIPATE. WILL TAKE TEMPS DOWN TO WITHIN A DEG OR TWO EITHER SIDE OF RECORD MINS AT MANY PLACES TONIGHT. SEE THE CLIMO SECTION FOR THE CURRENT RECORD MINS. THE COLD TEMPS ARE A CLASSIC SCENARIO FOR FOG IN THE NRN VALLEYS. THE AIR WILL BE SO DRY THAT IT WILL MAKE IT TOUGH TO FOG IN. WILL GO AHEAD AND MENTION PATCHY FOG FOR NOW. THOSE COLD TEMPS IMMEDIATELY AROUND KBFD COULD ALSO CREATE SOME FROST IN THE OPEN AREAS. WILL ALSO MENTION PATCHY FROST BUT NOT GO ADVY BECAUSE OF THE LOW PROBABILITY OF WIDESPREAD COVERAGE AND THE ALREADY- TENUOUS TEMP FORECAST. && .SHORT TERM /6 AM FRIDAY THROUGH 6 AM FRIDAY/... AFTER THE CHILLY START...FRIDAY WILL SEE A GOOD RECOVERY IN TEMPS. SCT-BKN CLOUDS MAY SNEAK INTO THE NW EARLY IN THE DAY AND THEN THE COLD AIR OVERHEAD WILL ALLOW A FEW DIURNAL CU TO FORM. MAXES UNDER 12-14C 8H TEMPS WORKS OUT TO HIGHS IN THE L70S IN THE HIGHEST ELEVATIONS AND L80S IN THE EASTERN VALLEYS. && .LONG TERM /FRIDAY THROUGH THURSDAY/... LATEST MEDIUM RANGE MODEL GUIDANCE SUGGESTS THAT THE UPPER FLOW PATTERN NOW IN PLACE...A LONGWAVE RIDGE OVER THE WESTERN U.S. AND LONGWAVE TROF OVER ROUGHLY THE EASTERN HALF OF THE COUNTRY...WILL PERSIST THROUGH THE LONG TERM PERIOD. HOWEVER...VARYING DEGREES OF STRENGTH AND POSITION WILL BE FORCED BY SHORTWAVES TRAVELING IN ACTIVE NORTHERN STREAM JET PUSHING SOUTH FROM CANADA. MEAN TROF PATTERN OVER THE EAST WILL BE CONDUCIVE TO NEAR TO BELOW NORMAL TEMPS ACROSS THE REGION FOR MUCH OF THE PERIOD...ALONG WITH LESS HUMID AIR. THOUGH MIN TEMPS SAT...SUN AND MONDAY MORNING WILL BE ABOVE NORMAL WITH SIG CLOUDS AND PCPN. PRECIP WISE WE ARE STILL LOOKING FOR A COMPLEX FRONTAL SYSTEM MOVING WEST TO EAST ACROSS PA FROM LATE SATURDAY INTO MONDAY AS A STRONG SHORTWAVE IS FORECAST TO DROP THROUGH THE GREAT LAKES AND AMPLIFY THE LONGWAVE TROF. THUS MAINTAINED THREAT OF WIDESPREAD SHOWERS AND THUNDERSTORMS ESPECIALLY SUNDAY MONDAY. A WARM FRONT ON THE LEADING EDGE OF THE SYSTEM WILL BE MOVE THROUGH PA ON SATURDAY INTO SATURDAY NIGHT...WITH ONLY ISOLD TO SCATTERED SHOWERS/TSRA EXPECTED. ON EITHER SIDE OF THIS WEATHER SYSTEM...COOL AND DRY HIGH PRESSURE WILL PREVAIL. EARLY NEXT WEEK EXPECT MIN AND MAX TEMPS TO BE 5 TO 10 DEGREES BELOW NORMAL STATEWIDE. THE WEATHER WILL BE NOTICEABLY COOLER AND LESS HUMID FOR USUALLY/CLIMATOLOGICALLY WARMEST WEEKS OF THE YEAR. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... LATE AFTN VISIBLE SATL IMAGERY SHOWING SCT-BKN CU WITH BASES BTWN 4-6KFT ACROSS CENTRAL PA. MUCH DRIER AIR WORKING IN FROM THE NORTH...COMBINED WITH APPROACH OF SUNSET...WILL CAUSE SKIES TO CLEAR LATER THIS EVENING. HIGH PRESSURE BUILDING OVER THE AREA TONIGHT WILL RESULT IN A NEAR CERTAINTY OF VFR CONDS AND LGT WIND FOR ALMOST ALL OF CENTRAL PA. THE EXCEPTION WILL BE THE DEEP VALLEYS OF THE ALLEGHENIES...WHERE UNSEASONABLY COOL TEMPS COMBINED WITH WARM RIVER/STREAM WATER AND A CALM WIND...WILL RESULT IN LOCALLY DENSE FOG A FEW HOURS EITHER SIDE OF DAWN. CLIMATOLOGY AND LATEST MOS GUIDANCE INDICATE KBFD IS THE ONLY AIRFIELD LIKELY TO EXPERIENCE A PERIOD OF LOW VSBYS...WHILE A SLIGHT CHANCE EXISTS AT KUNV...KAOO AND KIPT. ANY EARLY VALLEY FOG SHOULD BURN OFF BY 14Z...THEN A NEAR CERTAINTY OF VFR CONDS/LGT WIND FOR THE REST OF FRIDAY AS HIGH PRESSURE DRIFTS OVER THE STATE. OUTLOOK... SAT...PATCHY AM VALLEY FOG N...OTHERWISE VFR. SCT PM TSRA/MVFR POSS W. SUN...SHRA/TSRA WITH WARM FRONT PASSAGE MON...MORE WIDESPREAD SHRA/TSRA WITH COLD FRONT PASSAGE. && .CLIMATE... MIN TEMP RECORDS FRIDAY MORNING JULY 25TH: BFD - 39 SET IN 2013 - NOT LONG AGO BUT SHORT PERIOD OF RECORD JST - 45 SET IN 1957 AOO - 48 SET IN 1957 IPT - 48 SET IN 1953 MDT - 53 SET IN 1953 && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...LAMBERT/GARTNER AVIATION...DANGELO/FITZGERALD CLIMATE...

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