Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 242352 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 752 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/... DIURNAL CUMULUS FIELD ASSOCIATED WITH COOL AND FAIRLY DRY AIR ALOFT IS THINNING AND DISSIPATING ACROSS CENTRAL PA. MID CLOUD SHEARING INTO THE LOWER SUSQ RIVER VALLEY ASSOCIATED WITH 5H TROF CENTERED OVER SRN OHIO WILL BE SLIDING EASTWARD THROUGH LATE EVENING WITH DECREASING CLOUDS BY 02Z. CEXPECT MOST OF THE AREA TO BECOME CLEAR AND ALLOW TEMPS TO FALL OFF RAPIDLY. THE SET UP IS IDEAL FOR AN UNSEASONABLY COOL NIGHT. HIGH PRESSURE MOVES OVERHEAD...WHILE WINDS DIE DOWN AFTER THE CLOUDS DISSIPATE. FORECAST MINS REMAIN WITHIN A DEG OR TWO EITHER SIDE OF RECORD MINS AT MANY PLACES TONIGHT. SEE THE CLIMO SECTION FOR THE CURRENT RECORD MINS. THESE 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. BUT CLIMATOLOGY AND WATER TEMPS ARGUE STRONGLY FOR AT LEAST PATCHY COVERAGE...SO WILL KEEP PATCHY FOG. 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 /00Z FRIDAY THROUGH TUESDAY/...
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EVENING VISIBLE SATL LOOP SHOWING CU FALLING APART ACROSS CENTRAL PA AS SUNSET APPROACHES AND MUCH DRIER AIR WORKS IN FROM THE NORTH. CIRRUS DEBRIS FROM CONVECTION OVR VA IS DRIFTING OVR SE PA AT 23Z...BUT EVEN THAT SHOULD MOVE OUT BY LATE EVENING...LEAVING CLEAR SKIES FOR THE REST OF THE NIGHT. HIGH PRESSURE AND ASSOC DRY AIR MASS WILL RESULT IN A NEAR CERTAINTY OF VFR CONDS AND LGT WIND FOR ALMOST ALL OF CENTRAL PA TONIGHT. 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...SCT TSRA IMPACTS POSSIBLE...ESP NW MTNS. SUN...AM LOW CIGS POSS NW MTNS. SCT TSRA IMPACTS POSS SOUTHERN PA. MON...ONCL VIS RESTRICTIONS POSS IN SHRA/TSRA. TUE...NO SIG WX EXPECTED.
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&& .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/DEVOIR SHORT TERM...DANGELO LONG TERM...LAMBERT/GARTNER AVIATION...FITZGERALD CLIMATE...

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