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Area Forecast Discussion
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000
FXUS61 KCTP 171804
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
104 PM EST WED DEC 17 2014

.SYNOPSIS...
BRISK WESTERLY WINDS WILL BRING IN COLDER AIR THIS AFTERNOON.
SCATTERED...MAINLY MOUNTAIN SNOW SHOWERS ARE EXPECTED THROUGH THE
END OF THE WEEK AS CLOUDY AND COLD CONDITIONS PERSIST. A WEAK LOW
PRESSURE AREA IS EXPECTED TO MOVE SOUTH OF THE REGION THIS
WEEKEND...BUT MOST OF THE PRECIPITATION WILL STAY TO THE SOUTH OF
THE STATE.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
GUSTY WESTERLY WINDS WILL ADVECT SEASONABLY COLD AIR INTO THE
REGION THIS AFTERNOON. NARROW BANDS OF MAINLY LIGHT SNOW SHOWERS
WILL OCCUR ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST THIS
AFTERNOON...WHILE ANY SNOW SHOWERS THROUGHOUT THE CENTRAL RIDGE
AND VALLEY REGION FROM THE RELATIVELY SHALLOW STRATOCU DECK
WILL BE ISOLATED AND BRIEF /THANKS TO DECREASING LAPSE RATES IN
THE 850-700MB LAYER/. THE FAR SOUTHEAST WILL STAND THE BEST CHC
FOR SEEING A FEW BREAKS IN THE OTHERWISE EXTENSIVE CLOUD SHIELD
COVER.

NO REAL ACCUMULATIONS ARE EXPECTED TODAY WITH THE NEAR TO SLIGHTLY
ABOVE FREEZING TEMPS THROUGH THE AFTERNOON. HOWEVER...A COATING TO
ONE INCH OF SNOW IS POSSIBLE ACROSS THE HIGHER TERRAIN CLOSE TO
THE PA/NY BORDER WHERE MORE PERSISTENT/STEEPER LOW-MID LEVEL LAPSE
RATES WILL BE FOUND.

THE MAIN WEATHER STORY TODAY WILL BE THE WIND WITH 10-20 KTS
SUSTAINED AND GUSTS WELL INTO THE 20S. 

TEMPS WILL BE NEARLY STEADY FOR THE REST OF THE DAYLIGHT
HOURS...RANGING FROM 30-32 ACROSS THE NW MTNS AND LAURELS...TO THE
MID AND UPPER 40S IN THE LOWER SUSQ VALLEY.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM THURSDAY/...
COLD AIR FIRMLY IN PLACE FOR THE SHORT TERM. 

A COMPACT...THOUGH MDTLY STG MID-LEVEL SHORTWAVE WILL TRACK ESE
ACROSS THE FCST AREA BETWEEN ABOUT 00-07Z THURSDAY /AT THE NRN
EDGE OR LEFT EXIT REGION OF A POTENT 130 KT UPPER JET/ WITH A
DISTINCT POCKET OF RELATIVELY STEEP...850-700MB LAPSE RATES IN
EXCESS OF 5C/KM.

THIS FEATURE SHOULD SUPPORT A FEW HOUR PERIOD OF SCT-NUMEROUS
SNOW SHOWERS /THIS EVENING UNTIL SHORTLY AFTER MIDNIGHT/ WITH THE
POTENTIAL FOR A QUICK GROUND WHITENING - EVEN ACROSS THE CENTRAL
MTNS AND SUSQ VALLEY. MINS TONIGHT WILL FALL INTO THE 20S AND
EVEN SOME UPPER TEENS IN THE HIGHEST ELEVS OF THE LAURELS. WIND
CHILLS WILL BRUSH THE SINGLE DIGITS THERE.

BRISK...WEST TO WNW WINDS WILL CONTINUE THROUGH THE NIGHT. 

THURSDAY...WINDS MAY VEER JUST SLIGHTLY TO THE NORTHWEST. SPEEDS
OF 10-15 MPH AND GUSTS INTO THE L20S ARE POSSIBLE OVER THE
MOUNTAINS. CLOUD COVER WILL CONTINUE WITH THE CLASSIC UPSLOPE-
POST-FRONTAL CRUD HANGING OVER THE NWRN HALF OF THE CWA. THE FLOW
OFF THE LAKE WILL CREATE MORE SHSN. ACCUMULATIONS WILL BE
MINOR...AND CONFINED TO THE FAR NW AND VERY HIGHEST ELEVATIONS. NO
MORE THAN 2 INCHES EXPECTED IN WARREN COUNTY ON THE HIGH END. SOME
SUN MAY GET THE LOWER SUSQ INTO THE LOWER 40S. SUB-FREEZING MAXES
IN STORE FOR THE WRN MTS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
CYCLONIC FLOW ALOFT WILL WEAKEN ON THURSDAY AS UPPER LOW SHIFTS EWD 
ACROSS THE CANADIAN MARITIME REGION AND RIDGE ALOFT BUILDS OVER 
JAMES BAY. DESPITE A WELL ALIGNED WNW FLOW AND FAIRLY STRONG LOW 
LEVEL COLD AIR ADVECTION EARLY IN THE DAY...MODEL SOUNDINGS SHOW 
RATHER SHALLOW MOISTURE AND CAPPING INVERSION HGTS GENERALLY BELOW 
850MB WHICH SHOULD LIMIT SNOW ACCUMS TO AROUND 1 INCH IN MOST
AREAS IN THE NW MTNS. LOCALLY HIGHER AMOUNTS ARE POSSIBLE (2-4"
MAXIMUM ACCUMULATION POTENTIAL) OVER THE FAVORED PERENNIAL SNOWBELT
DURING THE 24 HOUR PERIOD ENDING 12Z FRI. THE PATTERN WILL REMAIN
SEASONABLY COLD AND BRISK THROUGH THE END OF THE WEEK. LARGE SCALE
SUBSIDENCE ASSOCIATED WITH SURFACE HIGH MIGRATING EAST FROM THE
GREAT LAKES/MIDWEST INTO EASTERN CANADA SHOULD BRING AN END TO
NUISANCE/MINOR SNOW SHOWER ACTIVITY AND LINGERING FLURRIES OVER
THE NW ALLEGHENIES BY FRI NGT.

CONCERNING THE WEEKEND SYSTEM...

THE MODELS SHOW A SOUTHERN STREAM TROUGH DEVELOPING TOWARD THE 
SOUTHERN ROCKIES AND PLAINS ON FRIDAY WITH THE ASSOCIATED HEIGHT 
FALLS INVIGORATING A WAVE OF LOW PRESSURE OVER THE WESTERN GULF 
COAST STATES BY 00Z SAT. THERE REMAINS A BROAD MODEL CONSENSUS IN 
TRACKING THE DEVELOPING SFC WAVE EAST-NORTHEAST ACROSS THE SOUTHEAST 
PIEDMONT BEFORE EXITING THE LOWER 48 INVOF THE CAROLINA COASTAL 
PLAIN---BETWEEN HATTERAS AND MYRTLE BEACH. WHILE THERE IS MUCH 
BETTER MODEL AGREEMENT AND CONVERGENCE TOWARD A WEAKER/MORE 
SUPPRESSED SOLUTION OVER THE LAST 2 MODEL CYCLES...THERE IS STILL 
ENOUGH SPREAD/UNCERTAINTY IN THE EVOLVING SPLIT-FLOW PATTERN THAT A 
MORE SIGNIFICANT STORM SYSTEM STILL CANNOT BE RULE OUT. HOWEVER 
CONFIDENCE IN A MAJOR STORM HAS LARGELY DIMINISHED SINCE YESTERDAY 
WITH THIS SCENARIO NOW LOOKING LIKE A LOW PROBABILITY OUTCOME. 
CONFIDENCE REGARDING THE STORM TRACK AND ASSOCIATED WEATHER IMPACTS 
HAS INCREASED SOMEWHAT (FROM LOW TO AVERAGE) GIVEN THE CONVERGENCE 
TOWARD A MORE COMMON SOLUTION...WITH A LIGHT RAIN/SNOW EVENT EMERGING
AS THE MOST LIKELY AND PROBABLE OUTCOME.

HIGH PRESSURE SHOULD PROVIDE A QUIET WEATHER PERIOD EARLY NEXT
WEEK BEFORE THE PATTERN TURNS INCREASINGLY UNSETTLED AND
POTENTIALLY STORMY HEADING INTO CHRISTMAS EVE/DAY.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
WIDESPREAD STRATO CU AND PERSISTENT MVFR TO IFR CIGS WITH
ISOLATED-SCATTERED AND GENERALLY BRIEF MVFR TO IFR VSBYS IN SNOW
SHOWERS WILL OCCUR ACROSS THE NW MTNS AND LAUREL HIGHLANDS /INVOF
KBFD AND KJST/ THROUGH FRIDAY MORNING. CONDITIONS ACROSS THE
CENTRAL MTNS AND SUSQ VALLEY WILL VARY BETWEEN LOW END VFR...AND 
MVFR CIGS.

GUSTY WEST TO WNW WINDS /UP AROUND 25 KTS AT TIMES/ WILL ADD SOME
MECHANICAL TURBULENCE DURING TAKEOFF AND FAP TO REGIONAL AIRFIELDS
THIS AFTERNOON THROUGH THURSDAY.

A SECONDARY COLD FRONT AND COMPACT UPPER AIR DISTURBANCE DROPPING
SE ACROSS THE REGION LATE TODAY AND EARLY TONIGHT COULD BRING
SOME BRIEFLY HEAVIER SNOW SHOWERS...WITH A COATING TO 1/2 INCH
POSSIBLE EVEN ACROSS THE CENTRAL MTN AND SUSQ VALLEY AIRFIELDS.

OTHERWISE...NOT A LOT GOING ON TILL MAYBE JUST BEFORE CHRISTMAS.
THERE COULD BE WIDESPREAD RAIN SHOWER ACTIVITY AROUND AS A POTENT
SFC AND UPPER LOW TRACKS NE TWD THE OHIO RIVER VALLEY.

OUTLOOK...

THU-FRI...MVFR CIGS POSS NW. OTHERWISE NO SIG WX EXPECTED.

SAT-SUN...SNOW/REDUCED VSBY...MAINLY ALONG THE MD BORDER.

&&

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

&&

$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...DANGELO/LAMBERT
LONG TERM...STEINBUGL
AVIATION...LAMBERT



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