Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 172007
AFDCTP

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

.SYNOPSIS...
BRISK WESTERLY WINDS WILL BRING IN COLDER AIR THIS AFTERNOON
THROUGH FRIDAY NIGHT. 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
WELL SOUTH OF THE REGION THIS WEEKEND...BUT MOST OR ALL OF THE
PRECIPITATION WILL STAY TO THE SOUTH OF THE STATE.

&&

.NEAR TERM /THROUGH TONIGHT/...
GUSTY WESTERLY WINDS WILL ADVECT SEASONABLY COLD AIR INTO THE
REGION LATE THIS AFTERNOON AND TONIGHT. NARROW...EAST-WEST BANDS
OF SNOW SHOWERS WILL OCCUR ACROSS MAINLY 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/. OCCASIONAL BREAKS
IN THE CLOUD DECK WILL OCCUR ACROSS THE SCENT AND SERN COUNTIES.

NO SNOW ACCUMULATION WILL OCCUR THROUGHOUT THE CENTRAL VALLEYS
AND NEAR THE ALLEGHENY FRONT WHERE TEMPS WILL BE IN THE MID TO
UPPER 30S. HOWEVER...A COATING TO ONE HALF OF AN INCH IS POSSIBLE
ACROSS THE HIGHER TERRAIN CLOSE TO THE PA/NY BORDER WHERE MORE
PERSISTENT/STEEPER LOW-MID LEVEL LAPSE RATES WILL BE FOUND.

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

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.

WEST TO NW WINDS WILL AVERAGE 10-15 KTS WITH GUSTS IN THE 20S
LATE TODAY THROUGH TONIGHT.

LOW TEMPS AT DAYBREAK THURS WILL BE NEAR 20F ACROSS THE HIGHER
TERRAIN OF THE NORTH AND WEST...AND IN THE MID TO UPPER 20S
THROUGHOUT THE SUSQ VALLEY.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
COLD AIR WILL STAY IN PLACE ACROSS THE FCST AREA THURSDAY INTO
FRIDAY.

THURSDAY...WINDS AT THE SFC AND ALOFT WILL VEER JUST SLIGHTLY TO
THE NORTHWEST. SPEEDS OF 10-15 MPH AND GUSTS INTO THE L20S ARE
POSSIBLE OVER THE MOUNTAINS. LITTLE OF NO CHANGE IN THE BLANKET OF
STRATUS AND STRATOCU CLOUDS IS EXPECTED THURSDAY AND THU
NIGHT...AND THE RELATIVELY SHALLOW COLD AIR BLOWING OVER THE LOWER
GLAKES WILL CREATE MORE SHSN ACROSS THE NRN AND WRN MTNS.

ACCUMULATIONS WILL BE MINOR...AND CONFINED TO THE FAR NW AND VERY
HIGHEST ELEVATIONS. AS STATED BY PREVIOUS SHIFTS NO MORE THAN 2
INCHES IS EXPECTED THROUGHOUT THE SNOWBELT OF NW WARREN COUNTY ON
THE HIGH END...SO NO LES ADVISORIES PLANNED ATTM. GLIMPSES OF
SUN MAY DEVELOP AGAIN ACROSS THE LOWER SUSQ...NUDGING TEMPS INTO
THE LOWER 40S /NEAR NORMAL FOR MID DEC/. MAX TEMPS ACROSS THE NRN
AND WRN MTNS WILL BE IN THE U20S TO L30S.

SIMILAR TEMPS AND SKY COVER EXPECTED AGAIN FOR THU NIGHT WITH
ISOLATED TO SCTD MTN SNOW SHOWERS. LITTLE IN THE WAY OF
ADDITIONAL SNOW ACCUM IS EXPECTED THOUGH AS MOISTURE WILL
CONTINUE TO BE QUITE SHALLOW WITH THE SUBSIDENCE INVERSION BASE
AOB 5 KFT AGL. A FEW HIGHLY LOCALIZED AMOUNTS IN THE 2-3 INCH
RANGE ARE POSSIBLE ACROSS THE FAVORED PERENNIAL SNOWBELT OF WARREN
COUNTY DURING THE 24 HOUR PERIOD ENDING 12Z FRI.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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 /20Z 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...LIGHT SNOW/REDUCED VSBY POSSIBLE ...MAINLY ALONG THE MD
BORDER.

MONDAY...MAINLY VFR. HOWEVER...AREAS OF MVFR STRATO CU ARE
POSSIBLE IN DEVELOPING SERLY LOW LEVEL FLOW.

&&

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

&&

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


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