Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 221211
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
811 AM EDT FRI AUG 22 2014

.SYNOPSIS...
A WEAK UPPER LOW OVER THE CATSKILL REGION OF NEW YORK WILL DRIFT
TO THE SOUTHEAST AS AN EXTENSIVE UPPER RIDGE BUILDS FROM THE
MISSISSIPPI VALLEY INTO EASTERN CANADA. THE EFFECT OF THESE
WEATHER FEATURES WILL BE TO CREATE ENOUGH RIDGING AT THE SURFACE
TO PUSH A BACKDOOR FRONT GRADUALLY WESTWARD TO THE ALLEGHENY
FRONT BY SATURDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS
WILL OVER THE REGION TODAY INTO TONIGHT. AFTER A CLOUDY AND COOL
START TO THE WEEKEND WITH AREAS OF DRIZZLE AND FOG...CONDITIONS
WILL DRY OUT SUNDAY AND EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ISOLATED LIGHT SHOWERS TRACKING TOWARDS THE NORTHWEST AND WEST
CENTRAL MOUNTAINS EARLY THIS MORNING AS AN ELONGATED UPPER SHEAR
AXIS IS APPROACHING FROM ONTARIO AND LAKE ERIE.

POPS WILL BE FAIRLY LOW THROUGH ABOUT 14-15Z. AFTERWARD...THE
FAIRLY JUICY...APPROX 1.5 INCH PWAT AIR WILL COMBINE WITH
DEVELOPING BREAKS OF SUNSHINE DURING THE MIDDAY HOURS TO QUICKLY
INCREASE SFC-BASED CAPES TO BETWEEN 1000-1500 J/KG THIS AFTERNOON.

BEST JET DYNAMICS AND LLVL THETA-E CONVERGENCE APPEARS TO FIRST
TARGET THE WRN MTNS /PARTICULARLY THE LAUREL HIGHLANDS DURING THE
LATE MORNING AND EARLY AFTERNOON/...BEFORE SPREADING EAST AND
BECOMING FOCUSED ACROSS SCENT PENN AND THE SUSQ VALLEY LATER THIS
AFTERNOON AND EARLY EVENING.

BASIN AVERAGE RAINFALL SHOULD BE AROUND 3 OR 4 TENTHS OF AN INCH
OVER THE UPCOMING 15 HOURS...THOUGH SHARP DIFFERENCES WILL
OBVIOUSLY OCCUR INVOF SMALL CLUSTERS OF SHRA/TSRA THAT ARE
EXPECTED TO TRACK ESE ACROSS THE CWA. HIGHEST POPS THROUGH 00Z SAT
WILL BE IN THE LIKELY CATEGORY AND EXTEND FROM NEAR KJST...NE TO
KAOO...KIPT AND KSEG. LOWEST POPS OF AROUND 30 PERCENT WILL BE
ACROSS THE FAR NW ZONES...TO THE WEST OF KBFD.

MAX TEMPS TODAY WILL VARY FROM THE MID 70S ACROSS THE NW...TO THE
LOWER 80S THROUGHOUT THE LOWER SUSQ VALLEY. THESE READINGS WILL BE
CLOSE TO NORMAL FOR LATE AUGUST.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
SCTD TO NUMEROUS SHOWERS WILL BE FOUND MAINLY ACROSS OUR CENTRAL
AND SWRN ZONES EARLY TONIGHT. AS THE AFOREMENTIONED BACKDOOR
PUSHES WWD TO THE ALLEGHENY FRONT...CONVECTIVE PRECIP WILL WANE
WITH STRATUS THICKENING UP/SPREADING WEST LATER TONIGHT. AREAS OF
DRIZZLE AND RIDGE-SHROUDING FOG ARE LIKELY LATE TONIGHT THROUGH
SATURDAY MORNING...WITH ANY LOW PROB FOR THUNDER LIMITED TO THE
AREA WEST OF ROUTE 219.

LOW TEMPS TONIGHT UNDER WIDESPREAD CLOUDS AND A LIGHT/MOIST
EASTERLY LLVL FLOW WILL BE 60-65F.

THE MOIST/ANOMALOUS EASTERLY SFC-850 MB FLOW ASCENDING THE
APPALACHIANS SHOULD LEAD TO WIDESPREAD LOW CLOUDS AND PATCHY
DRIZZLE/MTN TOP FOG PERSISTING THROUGH MOST OR ALL OF SATURDAY.
THIS WILL HELP TO KEEP TEMPS WELL BELOW NORMAL /PERHAPS BY A
SOLID 8-10F DURING THE DAY SATURDAY/. PORTIONS OF THE CENTRAL/NRN
MTNS MAY STRUGGLE TO CLIMB OUT OF THE UPPER 60S...WITH LOCATIONS
ACROSS THE SUSQ VALLEY...AND WEST OF RT 219 LIKELY REACHING THE
LOWER TO MID 70S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A WEAK UPPER LOW MOVING UNDERNEATH THE RIDGE SHOULD ALLOW FOR A
SLIGHT CHANCE FOR SHOWERS SATURDAY NIGHT. AFTERWARD...THE BUILDING
RIDGE WILL BE THE PRIMARY DRIVER OF OUR WX THRU MOST OF THE
EXTENDED FCST.

MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL
DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO
CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON
SUNDAY...BUT STILL REMAIN BLW NORMAL.

LARGE SCALE SUBSIDENCE AND DRY AIR SHOULD PERSIST...AS THE MID
RANGE MODELS ARE IN FAIR AGREEMENT OF A BUILDING RIDGE OVER THE
REGION THROUGH EARLY NEXT WEEK. BY MID NEXT WEEK THE FCST
CONFIDENCE BEGINS TO LOWER. BY THE MIDDLE OF NEXT WEEK...WHEN MED
RANGE MODELS BEGIN TO DIVERGE. GEFS KEEPS RIDGE AND FAIR WX GOING
THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A WEAK COLD FRONT
COULD PUSH SE INTO THE REGION...THE MODELS SEEM TO BE OFF WITH
THEIR TIMING. HAVE KEPT A LOW CHC OF TSRA WED INTO THURSDAY. WHAT
APPEARS CERTAIN IS THAT THE COOL TEMPS OF THIS WEEKEND WILL GIVE
WAY TO A SLOW WARMING TREND THRU THE FIRST HALF OF NEXT WEEK...AS
COOL AIR MASS MODIFIES UNDER STILL STRONG AUGUST SUN. GEFS AND EC
ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV NORMAL BY WED.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
LOW CIGS AND 3-6SM BR WILL ERODE/IMPROVE THROUGH LATE MORNING
WITH VFR CONDS BY THE AFTN. CONFIDENCE REMAINS LOW CONCERNING THE
TSTM OUTLOOK AND CONVECTIVE TRENDS...HOWEVER BRIEF TSTM IMPACTS
ARE POSSIBLE. MADE ONLY MINOR CHANGES TO PREVIOUS TAFS WITH THE
12Z ISSUANCE AND WILL ALLOW THE 15Z INTERMEDIATE UPDATE/18Z
SCHEDULED ISSUANCE ADDRESS CONVECTIVE DEVELOPMENT AND EVOLUTION.
ANY LINGERING STORMS SHOULD DECREASE IN COVERAGE AND INTENSITY
INTO TONIGHT.

A LARGE AREA OF HIGH PRES WILL BUILD SWWD FROM ERN CANADA INTO THE
NORTHEAST AND DOWN THE EAST SIDE OF THE APPLCHNS TNGT THRU THE
WEEKEND. EASTERLY FLOW SHOULD BRING LOW CLOUDS/CIGS INTO THE FCST
WITH SOME LIGHT RA/DZ EARLY SATURDAY WITH A FEW SHOWERS POSSIBLE
LATER IN THE DAY. LOOK FOR IMPROVING CONDS SUN THRU TUE.

OUTLOOK...
SAT...MVFR/IFR IN THE MORNING WITH PATCHY FOG/BR/-DZ/-RA...BCMG
VFR/MVFR IN THE AFTN WITH ISOLD-SCT SHRA.
SUN...LOW CIGS PSBL EARLY THEN BCMG VFR.
MON-TUE...VFR NO SIG WX.

&&

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

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...DEVOIR/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/CERU
AVIATION...STEINBUGL


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