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[Printable]
877
FXUS61 KCTP 010306
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1106 PM EDT FRI OCT 31 2014

.SYNOPSIS...
A STRONG UPPER-LEVEL TROUGH DROPPING SOUTHWARD FROM THE GREAT
LAKES WILL DEEPEN A LOW PRESSURE SYSTEM OFF THE MID-ATLANTIC
COAST ON SATURDAY. THIS LOW WILL EVENTUALLY TRACK SOUTHEAST OF
CAPE COD SATURDAY NIGHT AND SUNDAY. FOR PENNSYLVANIA...THIS WILL
LEAD TO MUCH CHILLIER AIR ARRIVING ON A BRISK NORTH TO NORTHWEST
WIND SATURDAY INTO SUNDAY. HIGH PRESSURE WILL RETURN TO THE AREA
BY MONDAY...WITH MODERATING TEMPERATURES INTO THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
SHOWERS ARE DISSIPATING ACROSS WESTERN PA LATE THIS EVENING...AS
UPPER-LEVEL LOW PRES SWINGS SOUTHWARD THROUGH THE OHIO VALLEY.
FATHER EAST...LLVL EASTERLY FLOW PICKING UP AND SOME LIGHT RAIN
DEVELOPING AS OFFSHORE LOW BEGINS TO STRENGTHEN.

THE HIGHER TERRAIN OF NRN AND WRN PA COULD SEE SOME SNOWFLAKES
MIX IN WITH ANY RAIN SHOWERS OVERNIGHT...AS COLDER AIR IS PULLED
INTO THE AREA.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
DEEP EASTERLY FLOW AROUND OFFSHORE SFC LOW SHOULD DELIVER A DAMP
MORNING TO MUCH OF EASTERN AND SOUTH-CENTRAL PA. DESPITE
RELATIVELY LOW DEEP LAYER MOISTURE...ANOMALOUS EASTERLY FLOW OF
THIS SORT TYPICALLY PRODUCES FAIRLY WIDESPREAD ALBEIT LIGHT RAIN.
POPS BEGIN TO DECREASE LATER IN THE DAY AS THE LOW PULLS
NORTHEASTWARD TOWARDS CAPE COD.

MARGINALLY COLD AIR MOVING INTO THE REGION SHOULD PROMOTE A
MIXTURE OF RAIN AND SNOW SHOWERS OVER THE LAURELS AND NORTHERN
MOUNTAINS...WITH LITTLE IF ANY ACCUMULATION EXPECTED DURING THE
DAYLIGHT HOURS. BACKING LOW LEVEL FLOW WILL ADVECT COLDER AIR
INTO THE REGION LATE SATURDAY AFTERNOON AND NIGHT. EARLY AFTERNOON
TEMPERATURES IN THE 40S WILL DROP SLOWLY ACROSS WESTERN AND
CENTRAL AREAS BY EVENING TO THE UPPER 30S TO LOWER 40S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
LARGE UPPER TROUGH WILL BECOME MORE NARROW AS IT DIGS SOUTHWARD
SAT NIGHT INTO SUN...WITH COASTAL LOW TO THE EAST LIFTING
NORTHEASTWARD. 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.

ENSEMBLE MEAN 8H TEMPS THIS WEEKEND POINT TOWARD DAYTIME HIGHS
FROM THE U30S-L40S OVR THE ALLEGHENIES TO 45-50F ACROSS THE LOWER
SUSQ VALLEY. THE COLDEST NIGHT WILL BE SUNDAY NIGHT...WHEN SFC
HIGH BUILDS OVR THE REGION AND SKIES CLEAR OUT. 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 INTO TUE...WHEN
ALL GUIDANCE BUILDS SFC HIGH AND ASSOC DRY AIR MASS ACROSS
PA...ALONG WITH MODERATING TEMPS. AN APPROACHING COLD FRONT WILL
BRING THE NEXT CHC OF SHRA LATE TUE INTO WED. FOLLOWED BY A
CLIPPER SYSTEM FOR LATE WEEK /MODELS DIVERGE ON TIMING/. BUT LATE
WEEK TREND WILL BE A RETURN BACK TO COOLER TEMPERATURES.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
SOME VARIATION WITH CONDITIONS AT BFD AND JST.

WILL CONTINUE TO UPDATE TAFS AS NEEDED.

EARLIER DISCUSSION BELOW.

ONE LOW OVER THE OH VLY...WITH NEW SYSTEM FORMING OFF
THE SE COAST.

RAIN WILL CONTINUE TO SLOWLY EDGE EASTWARD OVERNIGHT.
IFR AND MVFR CONDITIONS WILL DEVELOP FROM WEST TO EAST
AND PERSIST INTO SAT.

IT WILL BECOME WINDY ON SAT.

CONDITIONS WILL SLOWLY IMPROVE LATE SATURDAY INTO SUNDAY...AS
DRIER AND COLDER AIR WORKS SOUTHWARD FROM QUEBEC.

WINDS WILL REMAIN GUSTY INTO SUNDAY.

IT MAY BE COLD ENOUGH AT TIMES FOR RAIN TO MIX WITH
SOME SNOW AT SPOTS LIKE BFD AND JST.

OUTLOOK...

SUN...GUSTY NW WINDS. RAIN/SNOW SHOWERS ENDING WEST. LOW CIGS
WEST BECOMING VFR.

MON-TUE...NO SIG WX.

WED...MVFR WITH CHC SHRA.

&&

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

&&

$$
SYNOPSIS...EVANEGO
NEAR TERM...EVANEGO
SHORT TERM...DEVOIR/EVANEGO
LONG TERM...RXR
AVIATION...MARTIN




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