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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 250339
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1139 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/...
SKIES HAVE BECOME MOSTLY CLEAR AND TEMPS ARE FALLING OFF NICELY AS
EXPECTED. THE SET UP IS IDEAL FOR AN UNSEASONABLY COOL NIGHT WITH HIGH
PRESSURE...LIGHT WINDS AND PW AROUND 0.3" ACROSS MUCH OF CENTRAL
PA. HOURLY TEMPS ON TRACK FOR FORECAST MINS WITHIN A DEG OR TWO
OF RECORD MINS AT MANY PLACES EARLY FRIDAY.

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 /04Z FRIDAY THROUGH TUESDAY/...
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.

&&

.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...