Area Forecast Discussion
Issued by NWS State College, PA

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000
FXUS61 KCTP 302323
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
723 PM EDT THU OCT 30 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE APPALACHIANS TONIGHT. A VIGOROUS
UPPER LEVEL TROUGH DIGGING THROUGH THE CAROLINAS WILL SUPPORT THE
DEVELOPMENT OF A STRONG COASTAL STORM EXPECTED TO TRACK JUST OFF
THE EAST COAST THIS WEEKEND. THIS WILL LEAD TO MUCH COOLER AIR
BEING USHERED INTO THE REGION ON A BRISK NORTHERLY WIND. HIGH
PRESSURE WILL RETURN TO THE AREA BEHIND THE DEPARTING STORM SYSTEM
ON MONDAY WITH MODERATING TEMPERATURES INTO THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONFIDENCE IN SUNSHINE IS FADING AS THE INVERSION IS PROVING TO BE
HARD TO OVERCOME AS HIGH PRESSURE BUILDS IN FROM THE WEST. HAVE
ADJUSTED THE HOURLY TEMPS TO ACCOUNT FOR LESS SUNSHINE THAN
EXPECTED...BUT OVERALL FCST IS STILL ON TRACK WITH LITTLE MORE
THAN A FEW SPRINKLES EXPECTED IN A FEW LOCATIONS.

HIGH TEMPS WILL RANGE FROM THE MID 40S IN THE NW TO NEAR 60F IN
THE LOWER SUSQ.

DEEPER LAYERED CLOUDS WILL BE ON THE INCREASE OVERNIGHT AHEAD OF
THE APPROACHING SYSTEM TO OUR WEST. I BACKED OFF THE MENTION OF
SHOWERS REACHING WESTERN AREAS BY MORNING AS LATEST TIMING
SUGGESTS WE WILL REMAIN DRY INTO FRIDAY MORNING AT LEAST.

OVERNIGHT LOWS IN THE MID TO UPPER 30S WILL BE WITHIN A FEW DEG
EITHER SIDE OF NORMAL FOR LATE OCTOBER.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
MODELS ARE IN GOOD AGREEMENT WITH DEVELOPING AN AMPLIFYING UPPER
TROUGH OVER THE EASTERN US OVER THE NEXT 24-48 HOURS. THE UPSTREAM
ENERGY CAN BE SEEN CLEARLY ON WATER VAPOR IMAGERY AS AT LEAST A
PAIR OF SYSTEMS...THE FIRST MOVING THROUGH MISSOURI AND THE SECOND
JUST NORTH OF MINNESOTA.

UPPER FLOW OVER THE LOCAL AREA IS EXPECTED TO BACK QUICKLY TO THE
SOUTHWEST AND EVENTUALLY SOUTH AS A POTENT LOW CLOSES OFF AND
DIVES SOUTH THROUGH THE LOWER LAKES/OHIO VALLEY ON A TRACK TOWARD
THE CAROLINA COAST. MAIN FCST PROBLEM FOR FRIDAY IS HOW FAR EAST
SHOWERS WILL MANAGE TO INVADE AS THE UPPER LOW TO OUR WEST
DEVELOPS RAPIDLY AND DROPS SOUTH. THE TRACK OF THE LOW WELL TO OUR
WEST AND THEN SOUTH OF THE AREA SUGGESTS THERE WILL BE SOME
MEASURE OF SHORTWAVE RIDGING EAST OF THE SYSTEM...OVER PARTS OF
THE MID ATLANTIC AND NORTHEAST. AT THIS POINT IT LOOKS LIKE MOST
OF MY EASTERN FCST AREA COULD REMAIN DRY INTO FRIDAY
NIGHT...WHILE THE BEST CHANCE OF RAIN SHOWERS WILL BE OVER ABOUT
THE WESTERN HALF OF THE CWA. THE LACK OF DEEP MOISTURE SHOULD
RESULT IN FAIRLY LIGHT RAINFALL WITH THIS FEATURE...PERHAPS UP TO
A QUARTER INCH OVR THE W MTNS.

RISK OF SNOW OVER THE HIGHER ELEVATIONS OF THE LAURELS BY LATER
FRIDAY APPEARS LOW GIVEN LATEST MODEL SOUNDINGS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
FRIDAY NIGHT INTO SATURDAY THE LARGE UPPER LEVEL LOW WILL DROP
DOWN SOUTH AS ALL MEDIUM RANGE GUIDANCE CUTS OFF UPPER LOW SOUTH
OF PA AND MOVES IT DOWN INTO THE CAROLINAS. LATE FRIDAY
NIGHT...EARLY SATURDAY MORNING AS REMNANTS OF AN ASSOCIATED CLIPPER
LOW SHOULD DIE OVR THE CENTRAL APPALACHIANS AS ENERGY IS
TRANSFERRED TO DEVELOPING COASTAL LOW NR CAPE HATTERAS. HOWEVER
GIVEN THE MOISTURE...THE ADVECTION OF COLDER AIR...AND THE UPSLOPE
FLOW...THERE IS A GOOD CHANCE FOR SNOW SHOWERS OVER THE SW
ALLEGHENIES EARLY SATURDAY MORNING. THIS IS REINFORCED BY WWD
GRAPHICS AND MODEL SOUNDINGS. HAVE ADJUSTED WX GRIDS ACCORDINGLY.
 AS THE LOW DROPS SOUTH IT WILL BECOME A COASTAL STORM AND LIFT NE.
THIS WILL CAUSE A TIGHTENING PRESSURE GRADIENT AND BRING STRONG NW
FLOW DRAWING MUCH COLDER/DRIER AIR INTO PA.  OPERATIONAL RUNS AND
NEARLY ALL ENSEMBLE MEMBERS KEEP COASTAL LOW FAR ENOUGH OUT TO SEA
TO NOT DIRECTLY IMPACT CENTRAL PA. HOWEVER...COLD NW FLOW WILL
LIKELY PRODUCE SCT LAKE EFFECT SNOW SHOWERS ACROSS THE ALLEGHENY
PLATEAU AND PARTS OF THE CENTRAL MOUNTAINS SATURDAY NIGHT. GIVEN
DRYNESS OF AIR MASS MOVING IN...DON/T EXPECT ANY SIG ACCUMS...BUT
A COATING OF SNOW DOES APPEAR POSSIBLE OVR THE W MTNS.

TEMPS THIS WEEKEND WILL ALMOST CERTAINLY BE THE COLDEST YET THIS
SEASON. ENSEMBLE MEAN 8H TEMPS POINT TOWARD DAYTIME HIGHS FROM
THE U30S-L40S OVR THE ALLEGHENIES TO 45-50F ACROSS THE LOWER SUSQ
VALLEY. THE COLDEST NIGHT OF THIS OUTBREAK WILL LIKELY BE SUNDAY
NIGHT...WHEN SFC HIGH BUILDS OVR THE REGION. THOSE LOCATIONS THAT
HAVE YET TO SEE A FREEZE WILL LIKELY GET IT BY MONDAY AM.

HIGH CONFIDENCE IN A PERIOD OF DRY WEATHER SUNDAY/MONDAY...WHEN
ALL GUIDANCE BUILDS SFC HIGH AND ASSOC DRY AIR MASS ACROSS PA.
AN APPROACHING COLD FRONT WILL BRING THE NEXT CHC OF SHRA BY
MIDWEEK. DEEP UPPER TROF WILL LIFT OUT QUICKLY EARLY NEXT
WEEK...ALLOWING A MUCH MILDER RETURN SW FLOW TO OVERSPREAD THE
REGION. TEMPS LIKELY TO RETURN TO ABV NORMAL READINGS BY TUESDAY.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
NOT MUCH CHANGE TO 00Z TAFS. MAIN THING WAS TO GO WITH
BKN025 AT JST FOR A FEW MORE HOURS.

OVERALL...SC DECK THIN ACROSS THE NORTH...MORE COMPLEX DECK TO
THE SW. ALL SITES VFR NOW. EXPECT THAT TO BE THE TREND OVERNIGHT.

FLOW IS W TO NW...AND THE AIRMASS IS QUITE COLD. EXPECT SC
TO BE SLOW TO BREAK UP...AS FLOW STAYS FROM THE WEST AND
IS WEAK. ALSO INVERSION WILL LIKELY GO AGAINST MUCH CLEARING.

LATE TONIGHT...CLDS WORK BACK INTO THE FAR WEST...AS WEAK
LOW TRACKS TOWARD THE LOWER LAKES EARLY FRIDAY. PERHAPS
A FEW SHOWERS FAR WEST BY EARLY FRIDAY AFT.

MORE DETAIL ON FRIDAY BELOW.

LAYERED CLOUDS WILL BE INCREASING ONCE AGAIN ON FRIDAY AS A
POTENT UPPER TROUGH MOVES OVER THE REGION. EXPECT MVFR CONDITIONS
TO DEVELOP ALONG WITH RAIN SHOWERS FRIDAY...MAINLY OVER ABOUT THE
WESTERN HALF OF THE FLYING AREA. MUCH OF MY EASTERN FORECAST AREA
WILL REMAIN VFR INTO FRIDAY NIGHT.

OUTLOOK...

SAT...MVFR/IFR WITH SCATTERED RAIN/SNOW SHOWERS WEST. VARYING
CONDS FROM VFR-MVFR CENTRAL/EAST WITH OCNL -SHRA. N-NW WIND GUSTS
25-30 MPH.

SUN...RAIN/SNOW SHOWERS ENDING WEST. LOW CIGS WEST BECOMING VFR.
GUSTY NNW WINDS GRADUALLY DECREASING.

MON-TUE...NO SIG WX.

&&

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

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...CERU
AVIATION...LA CORTE/MARTIN



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