Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 040551
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
151 AM EDT FRI SEP 4 2015

.SYNOPSIS...
ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO NEXT WEEK WITH
GRADUALLY DECREASING HUMIDITY LEVELS. ISOLATED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE TODAY AND AGAIN FRIDAY AFTERNOON. HIGH
PRESSURE WILL ENSURE FAIR AND DRY WEATHER FOR LABOR DAY WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
STILL WATCHING THE SLOW DISSIPATION OF DIURNALLY FUELED CONVECTION
OVER THE NORTHWEST MOUNTAINS...WHICH ARE BEING MAINTAINED ALONG
THE EASTERN PERIPHERY OF NEARLY STATIONARY H5 SHEAR AXIS OVER
EASTERN OHIO. EARLIER LOCALLY HEAVY RAINFALL HAS DECREASED...BUT
WESTERN PORTIONS OF WARREN COUNTY ARE STILL SEEING HEAVY LATE
EVENING DOWNPOURS AS CELLS SLOWLY WEAKEN AND DRIFT WNW.
EXTENDED POPS BEYOND 03Z ACROSS THE NORTHWEST MOUNTAINS AND LAUREL
HIGHLANDS...WHERE ISOLATED SHOWERS ARE STILL PROPAGATING. MUCH
WEAKER FORCING CONTINUES TO MAINTAIN ISOLATED SHOWERS OVER
LANCASTER COUNTY AND THE PIEDMONT REGION OF SOUTHEAST PA.

CONTINUED STABILIZATION SHOULD END ACTIVITY IN MOST AREAS BY
MIDNIGHT. PERSISTENCE AND TIME OF YEAR MAKE A STRONG CASE FOR
OVERNIGHT FOG/REDUCED VISIBILITY INTO FRIDAY MORNING.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
UPPER LEVEL RIDGING WILL REMAIN A DOMINANT FEATURE INTO THE
WEEKEND. SHORT TERM MODEL GUIDANCE STILL SHOWS A LOW TO MEDIUM
CHANCE FOR ISOLATED/SCATTERED TSTMS FRIDAY AFTN AS WEAKER S/WV
IMPULSES DRIFT SEWD WITHIN SHEAR/INSTABILITY/MSTR AXIS FROM THE
GREAT LAKES ACROSS THE N-CENTRAL APPALACHIANS. A BACKDOOR COLD
FRONT SHOULD ALIGN ITSELF NEAR THIS AXIS AND PROVIDE ENOUGH LOW
LEVEL CONVERGENCE TO SPARK SOME CONVECTION OVER CENTRAL AND
ESPECIALLY SRN PA PER MULTI MODEL CONSENSUS. DIURNAL COOLING
SHOULD ALLOW ANY STORMS TO DISSIPATE THRU FRI EVE. THE BOUNDARY
SHOULD PIVOT TO A NNW/SSE ORIENTATION ON SATURDAY WHILE BEING
SHUNTED SWWD...AS A LARGE DOME OF SFC HIGH PRESSURE MOVES FROM ERN
QUEBEC INTO NEW ENGLAND. RISK AREA FOR STORMS ON DAY 3 SHOULD BE
POSITIONED TO THE WEST OF THE LOCAL CWA. TEMPERATURES SHOULD COOL
OFF A BIT WITH NOTICEABLY LESS HUMID AIR ARRIVING BY SATURDAY
NIGHT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
NOT MUCH TO CHANGE IN A SLOWLY EVOLVING EXTENDED FORECAST. HIGH
PRESSURE SHOULD MAINTAIN DRY WEATHER SUNDAY-MONDAY. LEAD COLD
FRONT ADVANCING EWD FROM THE GREAT LAKES/MIDWEST AND POTENTIAL
ONSHORE FLOW MSTR MAY IMPACT THE FCST BY TUESDAY WITH SCT TSTMS
POSS...BUT A CONSENSUS SOLUTION HOLDS BACK HIGHER POPS UNTIL WED
OR MAYBE EVEN THU IN ASSOCIATION WITH A STRONGER SHORTWAVE/SFC
COLD FRONT. SO TIMING DIFFS WILL NEED TO BE RESOLVED AS THE RIDGE
SLOWLY BREAKS DOWN.

THE GLOBAL NUMERICAL MODELS/ENSEMBLES ARE COMING INTO BETTER
AGREEMENT ON A PATTERN CHANGE DURING THE SECOND HALF OF NEXT WEEK
WITH A SHUFFLING OF THE LONGWAVE FLOW ALLOWING EWD PROGRESSION OF
THE WESTERN TROUGH INTO THE CENTRAL STATES AND RECENT RIDGE OVER
THE EASTERN UNITED STATES OFF THE COAST INTO THE WRN ATLC. THIS
SHOULD EVENTUALLY BRING AN END TO THE RECENT HOT/DRY SPELL. A
RETURN TO SEASONAL TEMPERATURES AND MORE ACTIVE PCPN PATTERN
SEEMS PROBABLE BY NEXT WEEKEND IN THE NEW FLOW REGIME.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
MCLEAR SKIES AND A NEARLY CALM WIND WILL ONCE AGAIN LEAD TO PATCHY
DENSE FOG IN THE VALLEYS OF CENTRAL PA EARLY THIS MORNING.
CONDITIONAL CLIMATOLOGY AS WELL AS LATEST MDL GUIDANCE IMPLY A
NEAR CERTAINTY OF IFR/LIFR CONDS DEVELOPING EARLY THIS AM AT KBFD.
ELSEWHERE...A BRIEF PERIOD OF IFR CONDS APPEAR POSSIBLE AT
KIPT/KAOO/KJST/KUNV ARND DAWN. AT KMDT/KLNS...SIG REDUCTIONS
APPEAR UNLIKELY THIS MORNING.

ANY EARLY FOG SHOULD BURN OFF BY LATE AM. THE REST OF THE DAY WILL
FEATURE WIDESPREAD VFR CONDS AND LIGHT WINDS. HOWEVER...A COLD
FRONT BACKING IN FROM THE EAST WILL SPAWN SCT PM TSRA...MAINLY
ACROSS SOUTHERN PA. A BRIEF VIS REDUCTION IS POSSIBLE IN A FEW
SPOTS FROM THESE STORMS...MAINLY BTWN 18Z-00Z.

A MOIST SERLY FLOW BEHIND THE COLD FRONT WILL LIKELY PRODUCE SOME
LOW CIGS ACROSS THE MTNS OF CENTRAL PA TONIGHT AND EARLY SAT AM.

OUTLOOK...

SAT...AM LOW CIGS POSS...MAINLY KBFD/KJST.

SUN-TUE...PATCHY AM FOG POSS...MAINLY KBFD/KIPT.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...GARTNER
NEAR TERM...DEVOIR/GARTNER
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...RXR/STEINBUGL
AVIATION...FITZGERALD


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