Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 201518
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1018 AM EST THU NOV 20 2014

.SYNOPSIS...

AN ARCTIC COLD FRONT WILL PUSH EAST ACROSS THE SUSQUEHANNA VALLEY
THIS MORNING. COLDER THAN NORMAL CONDITIONS WILL FOLLOW IN ITS
WAKE ON A GUSTY WESTERLY WIND...AND LAST THROUGH FRIDAY. HIGH
PRESSURE WILL BRING MORE TRANQUIL CONDITIONS SATURDAY BEFORE AN
APPROACHING STORM SYSTEM BRINGS A CHANCE OF RAIN SHOWERS SUNDAY
INTO THE FIRST PART OF TUESDAY.

&&

.NEAR TERM /UNTIL 4 PM THIS AFTERNOON/...

THE COLD FRONT IS ENTERING THE LOWER SUSQ VALLEY AS OF MID
MORNING...AND WILL CONTINUE RAPIDLY EAST OVER THE NEXT SEVERAL
HOURS. LITTLE OR NO PRECIPITATION IS ASSOCIATED WITH THE
FRONT...ITS MAIN EFFECT IS TO USHER IN A GUSTY WESTERLY WIND ALONG
WITH ANOTHER COLDER THAN NORMAL AIRMASS.

OTHER THAN SOME SCATTERED FLURRIES OVER WESTERN AND EVEN CENTRAL
AREAS...ANY SIG PRECIP WILL HOLD OFF UNTIL LATER TODAY AND
OVERNIGHT AND WILL EVENTUALLY BECOME FOCUSED OVER OUR LAKE EFFECT
SNOW BELT AREAS OF THE NORTHWEST AND PARTS OF THE LAURELS.

DEEPENING COLD AIR AND INCREASED DIURNAL VERTICAL MIXING WILL TAP
THE STRONGER WSW WINDS ALOFT AND CREATE FREQUENT GUSTS IN THE 25
TO 35 MPH RANGE TODAY. COMBINE THE GUSTS WITH TEMPS THAT WILL BE
ANYWHERE FROM 15 TO 20 DEG BELOW NORMAL AND WE HAVE SOME VERY
COLD WIND CHILLS IN STORE THROUGH FRIDAY...RANGING FROM JUST THE
SINGLE DIGITS AND TEENS BY DAY...AND FROM ABOUT 10 ABOVE TO 5
BELOW ZERO TONIGHT.

MEAN WIND FROM THE WEST IN THE DEEPENING MIXED LAYER WILL KEEP THE
HEAVIEST SINGLE LAKE EFFECT BAND ANCHORED NEAR THE INTERSTATE 90
CORRIDOR THROUGH MOST OR ALL OF THE DAYLIGHT HOURS TODAY.

A WEAK TROUGH WILL CROSS THE LOWER GLAKES LATE THIS AFTERNOON AND
EARLY THIS EVENING...PUSHING THE SNOW BAND GRADUALLY SOUTH AND
MORE INLAND...BEFORE THE SHORTENED FETCH ACROSS THE LAKE AND
INCREASED DIRECTIONAL SHEAR BREAKS UP THE LES INTO SEVERAL NARROW
BANDS.

THE LENGTH OF THIS EVENT WILL BE SHORTER THAN WHAT WAS JUST
EXPERIENCED ACROSS NW PA...SO SNOW TOTALS SHOULD BE HALF TO THREE
QUARTERS OF THE LOCALLY VERY HEAVY SNOW OF 1 TO 1.5 FEET THAT FELL
ACROSS FAR NWRN WARREN COUNTY OVER THE ROUGHLY 48 HOUR PERIOD
BETWEEN LAST THURSDAY AND LAST SAT MORNING.

ENS MEAN 8H TEMPS CONTINUE TO SUPPORT HIGH TEMPS THIS AFTERNOON
FROM JUST THE L20S ACROSS THE NW MTNS...TO PERHAPS THE U30S ACROSS
YORK/LANCASTER COUNTIES.

&&

.SHORT TERM /4 PM THIS AFTERNOON THROUGH 6 PM FRIDAY/...
VERY COLD AND WINDY CONDITIONS WILL PREVAIL LATE TODAY THROUGH
FRIDAY WITH SCATTERED SNOW SHOWERS ACROSS THE NRN AND WESTERN
MTNS...AND LOCALLY HEAVY LAKE EFFECT SNOWS ACROSS OUR FAR NW
ZONES. GENERALLY LIGHT ACCUMS OF A COATING TO 2 INCHES WILL OCCUR
ACROSS THE ALLEGHENY PLATEAU /TO THE EAST OF RT 219/ WHILE
LOCALIZED AMTS OF 3 OR 4 INCHES WILL BE POSSIBLE ACROSS THE SKI
COUNTRY OF THE LAUREL HIGHLANDS.

ELSEWHERE...FLURRIES AND EVEN SOME ISOLATED/NARROW BANDS OF LES
BLOWING WELL INLAND ON AN APPROX 310 DEG AXIS WILL AFFECT THE
CENTRAL RIDGE AND VALLEY REGION AND COMMUNITIES ALONG THE WEST
BRANCH OF THE SUSQ RIVER.

WIND GUSTS TONIGHT COULD TOP OUT BETWEEN 40-45 MPH AT
TIMES...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE STATE /WITHIN
THE DESCENDING/THERMALLY DIRECT BRANCH OF A STRONG 140-150 KT
UPPER JET...STRETCHED FROM THE OHIO VALLEY TO THE NJ COAST/.

LOW TEMPS TONIGHT WILL BE IN THE LOW TO MID TEENS ACROSS THE NRN
AND WRN MTNS...AND UPR TEENS TO LOW 20S FURTHER SE.

HIGH TEMPS FRIDAY WILL BE VERY SIMILAR...IF NOT A FEW DEG F COLDER
THAN TODAY.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS NE FROM THE OHIO VALLEY LATE FRIDAY INTO
SATURDAY BRINGING CLEARING SKIES AND DIMINISHING WIND.

MORE IN THE WAY OF SUNSHINE AND A WARMING TREND WILL OCCUR ON
SATURDAY...AS THE HIGH BECOMES CENTERED OVER THE MID ATLANTIC
REGION.

A WARM FRONT AND LIMITED MOISTURE RETURN ARRIVING FROM THE OHIO
VALLEY WILL BRING THICKENING CLOUDS AND A CHANCE OF WET SNOW AND
RAIN FOR LATE SAT AND SATURDAY NIGHT.

MILDER TEMPERATURES ARE IN STORE FOR THE LATER PART OF THE
WEEKEND INTO EARLY NEXT WEEK...BUT SOME CHANCE OF SHOWERS INTO
TUE.

DID UP TEMPS SOME...GIVEN RATHER STRONG WARM ADVECTION.

ALSO DID UP POPS SOME FOR SUNDAY NIGHT INTO MONDAY...GIVEN
TYPE OF AIRMASS BEING ADVECTED NORTHWARD.

COOLER AGAIN BY MID WEEK...BUT NOT AS COLD AS WHAT WE HAVE
NOW.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...

A GUSTY WEST WIND OF 15-25KT TODAY WILL DIMINISH TO 5-15KT
OVERNIGHT.

CONDITIONS WILL BE VARIABLE IN THE COLD GUSTY FLOW BEHIND THE COLD
FRONT. WHEN SNOW SHOWERS ARE OCCURRING VISIBILITIES WILL BE IN
THE 1-3 MILE RANGE AND UNLIMITED THE REST OF THE TIME. SIMILARLY
CEILINGS WILL VARY BETWEEN ABOUT 1500-4000`. SO CONDITIONS WILL
FLUCTUATE BETWEEN IFR AND VFR OVER OUR WESTERN AND CENTRAL
TERMINALS FOR MUCH OF TODAY.

BY LATER TODAY INTO TONIGHT THE PATTERN SHOULD SETTLE INTO A MORE
FAMILIAR ONE WHERE MOST OF THE REGION IS VFR WHILE THE HIGHER
WESTERN AND NORTHERN ELEVATIONS REMAIN MVFR WITH OCNL IFR IN
SCATTERED SNOW SHOWERS. BRADFORD STANDS THE HIGHEST CHANCE OF
SIGNIFICANT REDUCTIONS AS LAKE EFFECT SNOW BANDS SETTLE INTO THE
NWRN PART OF THE STATE OVERNIGHT INTO FRIDAY.

OUTLOOK...

FRI...SCATTERED SNOW SHOWERS WITH MVFR/IFR MAINLY WEST/NORTH.
CENTRAL AND EASTERN AREAS MAINLY VFR.

SAT...MAINLY VFR.

SUN...MAINLY VFR WITH A CHANCE OF RAIN SHOWERS.

MON...MVFR WITH RAIN SHOWERS.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY FROM 5 PM THIS AFTERNOON TO 3 PM EST
FRIDAY FOR PAZ005.
LAKE EFFECT SNOW WARNING FROM 5 PM THIS AFTERNOON TO 3 PM EST
FRIDAY FOR PAZ004.

&&

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


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