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Area Forecast Discussion
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000
FXUS61 KCTP 240544
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1244 AM EST MON NOV 24 2014

.SYNOPSIS...
STRONG LOW PRESSURE WILL PUSH NORTHWARD THROUGH THE GREAT LAKES
LATE TONIGHT AND MONDAY. IT WILL BRING A SLUG OF RAIN THROUGH THE
STATE TONIGHT. VERY WARM AND EVEN NEAR-RECORD WARM TEMPERATURES
ARE EXPECTED OVER MUCH OF THE AREA MONDAY...BEFORE THE COLD AIR
FOLLOWING THE GREAT LAKES LOW MOVES ACROSS LATE MONDAY AND MONDAY
NIGHT. A DEEPENING AREA OF LOW PRESSURE WILL MOVE NORTHWARD ALONG
THE MID ATLANTIC COAST WEDNESDAY. THERE IS A LOW CONFIDENCE AS TO
WHAT THE EXACT PATH OF THIS STORM WILL BE. HOWEVER...THE EASTERN
THIRD TO HALF OF THE STATE COULD HAVE A SIGNIFICANT SNOWFALL. COLD
AIR WILL FOLLOW FOR NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WARM FRONT LIFTING THROUGH THE VIRGINIAS EARLY THIS MORNING WITH
STRONG SOUTHERLY FLOW ALOFT. VIGOROUS UPPER TROF LIFTING THROUGH
CENTRAL AND EASTERN OHIO WITH WIDESPREAD LIGHT TO MODERATE RAIN
SHIELD EXTENDING FROM NORTHEAST OHIO THROUGH ALL BUT FAR SOUTHWEST
PA. BACK EDGE OF RAIN SHIELD MAKING STEADY PROGRESS NNE

AS PREVIOUSLY MENTIONED...FAST NORTHWARD PROPOGATION OF RAIN
PRECLUDES ANY CONCERNS FOR HEAVY RAIN. GENERAL 0.50 INCHES QPF IS
EXPECTED...BUT SOME HEAVIER AMOUNTS ARE POSSIBLE FAR SOUTHEAST
WHERE CONVECTIVE INSTABILITY IS PREVENT. KEPT MENTION OF T THERE
FOR THE OVERNIGHT.

WINDS ALOFT GET UP TO 50 KTS OVER THE CENTRAL MTNS...BUT THE
GENERAL STABILITY OVER THE BULK OF THE AREA SHOULD KEEP GUSTS DOWN
DURING THE NIGHT. THE EXCEPTION COULD BE THE HIGHER PEAKS IN THE
WEST WHICH COULD BE GUSTY /INTO THE 20 PLUS KT RANGE/ THROUGH THE
NIGHT. TEMPS WILL LIKELY LEVEL-OFF OR EVEN RISE LATER TONIGHT.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
SUBSIDENCE/DRYING IMMEDIATELY BEHIND THE OVERNIGHT WAVE WILL START
THE BREAK-UP OF THE CLOUDS FROM S-N. HOWEVER...THE AMBIENT
MOISTURE WILL BE HIGH IN THE LLVLS AND FLOW OUT OF THE SOUTH
THROUGH THE COLUMN WILL MAKE IT DIFFICULT TO CLEAR THE NORTHERN
HALF OF THE AREA TOO RAPIDLY. THE SOUTH WILL LIKELY GET SOME
DECENT CLEARING AND THE WARM AIR AHEAD OF THE COLD FRONT WILL PUSH
TEMPS TO NEAR-RECORD LEVELS ON MONDAY AFTERNOON. WILL KEEP THE
NUMBERS SLIGHTLY LOWER THAN RECORDS...THOUGH. THIS IS DUE TO THE
UNCERTAINTY OF HOW MUCH SUN TIME WE WILL HAVE. THE BIGGEST TEMP
BUST POTENTIAL AREA /STAY TOO COOL VS FCST/ WILL BE THE
NORTHEASTERN MTNS. THEY COULD STAY TOO CLOUDY. THE INSTABILITY
COULD ALSO TOUCH OFF A FEW SHOWERS -MAINLY IN THE CENTRAL AND
NORTH. THE COLD FRONT SHOULD MOVE THROUGH LATER IN THE DAY AND
EARLY EVENING.

THE WINDS WILL BE THE OTHER STORY - ALONG WITH THE TEMPS. THE
WESTERN MOUNTAINS/ALLEGHENIES WILL BE THE GUSTIEST PLACE. MIXED-
WINDS WITH LITTLE DIRECTIONAL SHEAR OFF BUFKIT SOUNDINGS MAKE FOR
WIND GUSTS EASILY INTO THE UPPER 30KT RANGE...LIKELY INCREASING TO
OCNLY 40-43 KTS IN THE LATE AFTERNOON AND NIGHT. A WIND ADVISORY
WAS RECENTLY ISSUED FOR 17Z MONDAY - 09Z TUESDAY FOR THE NW MTNS
AND LAUREL HIGHLANDS.

THE PERIOD OF LIKELY HIGHEST GUSTS APPEAR TO BE NEAR...AND FOR SEVERAL
HOURS IN THE WAKE OF THE CFROPA /OR FROM 21Z MONDAY TO 05Z
TUESDAY/.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
POTENTIAL FOR SIG WINTER IMPACTS FROM LOW PRESSURE MOVING UP THE
EAST COAST ON WED/WED NIGHT. WILL CONTINUE TO INJECT
INTERPRETATION OF THE LATEST MODEL GUIDANCE WITH EACH 3-HOURLY
UPDATE TO GUIDE DECISION SUPPORT LEADING UP TO THE PRIME TRAVEL
PERIOD FOR THE THANKSGIVING HOLIDAY.

HIGHLY AMPLIFIED AND ACTIVE UPPER AIR PATTERN WILL BRING A PERIOD
OF ACTIVE WEATHER THROUGH THE COMING WEEK. THE 500MB CONFIGURATION
WILL FEATURE ANOMALOUS RIDGING ALONG THE WEST COAST AND IN THE
WESTERN ATLANTIC WITH A FULL-LATITUDE PERSISTENT TROUGH EBBING
AND FLOWING OVER THE CENTRAL AND EASTERN U.S. 

AFTER THE EXIT OF MONDAY/S LOW PRESSURE AREA...COLDER TEMPS
RETURN ON BRISK W/SW FLOW FOR TUE DROPPING HIGHS SOME 20-25F FROM
PREV DAYS READINGS. WE/LL ALSO SEE THE RETURN OF LIGHT SNOW
SHOWERS IN THE WESTERN HIGHER TERRAIN.

THEN FOCUS WILL TURN TO A WAVE CURRENTLY DROPPING SE FROM BRITISH
COLUMBIA AND WASHINGTON STATE...WHICH WILL SPAWN AN AREA OF LOW
PRESSURE OVER THE SE US TUESDAY NIGHT...THAT WILL LIKELY MOVE
NORTH NORTHEASTWARD JUST OFF THE EAST COAST WEDNESDAY INTO
THURSDAY.

12Z/18Z OPERATIONAL AND GEFS RUNS ALONG WITH THE 21Z SREF ARE
BECOMING FAIRLY WELL CLUSTERED WITH RESPECT TO THE LOCATION OF THE
NEAR...TO SUB-1000 MB SFC LOW EARLY WED EVENING /NEAR...AND UP TO
ABOUT 200 NM EAST OF DELMARVA PENINSULA/.

THERE IS STILL MUCH UNCERTAINTY AT THIS 60-72 HOUR TIMEFRAME
BEFORE THE EVENT...WITH RESPECT TO THE EXACT TRACK OF THE SFC LOW
AND ASSOCIATED SNOW/RAIN AMOUNTS.

COLD AIR WILL BE IN PLACE WED MORNING AS A /WEAK/ HIGH PRESSURE
RIDGE RETREATS TO THE NORTH AHEAD OF THE APPROACHING LOW.
NORTHERLY FLOW OVER CENTRAL PA NOT PARTICULARLY STRONG IN ANY
MODEL...BUT A SHORTWAVE LOOKS POISED TO SLIDE IN FROM THE GREAT
LAKES ON WED TO ADD SOME SYNOPTIC LIFT TO A RAPIDLY DEEPENING AND
FAST MOVING SURFACE LOW.

THE 12Z ECMWF AND IT'S ENSEMBLE ARE VERY SIMILAR HUGGING THE SFC
LOW ALONG THE SHORELINE...WHILE US/CANADIAN MODELS AND THEIR
ENSEMBLES ARE FURTHER EAST BY 100-200 NM. EXPERIENCE SHOWS THAT
THE LACK OF A SIGNIFICANT BLOCKING HIGH TO OUR NORTH OR
NORTHEAST...FAVORS A MORE WESTERN TRACK /SIMILAR TO THE EC AND ITS
ENSEMBLE/. SHOULD THE WWD TREND CONTINUE EVEN FURTHER WITH AN
EARLIER INJECTION OF NRN STREAM ENERGY INTO THE SOUTHERN STREAM
SYSTEM...IT/S CONCEIVABLE THAT OUR FAR SE ZONES /NEAR KLNS AND
KMDT/ COULD EVEN SEE A MIX WITH SLEET AND RAIN FOR A PERIOD THAT
WOULD HOLD DOWN ACCUMULATIONS.

PRECIP MAY START OFF EARLY WED AS A MIX OF RAIN AND SNOW IN THE
SE...BUT COOLING TEMPS ALOFT SHOULD CONVERT ALL PRECIP OVER TO
SNOW BY MIDDAY. AS IS A GENERAL RULE WITH THESE TYPES OF EVENTS...
THERE WILL LIKELY BE A SHARP DROPOFF IN ACCUMULATIONS ON THE NW
EDGE OF THE HEAVIER SNOWS. BIGGEST POTENTIAL IMPACTS IN OUR CWA
WILL BE THE CENTRAL MTNS AND SUSQ VALLEY...WHERE POTENTIAL FOR A
SEVERAL HOUR PERIOD OF HEAVY ACCUMULATING SNOW WILL EXIST. BUT
AGAIN...SMALL CHANGES IN THE ULTIMATE TRACK COULD LEAD TO
MODIFICATIONS OF SNOWFALL FORECASTS. THE TAKE AWAY...THOUGH THE
DETAILS REMAIN UNCERTAIN...THERE WILL BE SIG IMPACTS TO TRAVEL
ALONG THE U.S. EAST COAST ON ONE OF THE BUSIEST DAYS OF THE YEAR
/WED/. PLAN ACCORDINGLY.

COLDER AIR REMAINS IN PLACE LATE IN THE WEEK AS SCT SNOW SHOWERS
RETURN TO THE WESTERN HIGHER TERRAIN. TEMPS LOOK TO GRADUALLY
MODIFY LATE WEEKEND HEADING INTO NEXT WEEK...WITH NO BIG STORM
SYSTEMS EXPECTED AFTER THANKSGIVING.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A LOW PRES SYSTEM TRACKING NORTHWARD INTO THE GRT LKS WILL SPREAD
LOWERING CIGS AND RAIN ACROSS CENTRAL PA TONIGHT. REGIONAL RADAR
AT 00Z SHOWS THE RAIN ABOUT TO ENTER SOUTHERN PA AND LINEAR
EXTRAPOLATION SUGGESTS THE RAIN WILL OVERSPREAD ALL CENTRAL PA
AIRFIELDS BTWN 02Z-04Z. A BLEND OF LATEST LAMP GUIDANCE...SREF AND
HRRR MDL OUTPUT IMPLY CIGS WILL DROP TO IFR BTWN 04Z-06Z...JUST A
COUPLE HOURS AFTER THE RAIN BEGINS. 

SOUTHERLY WINDS IN THE 1-2 KFT LAYER WILL BECOME VERY STRONG
OVERNIGHT...MAKING LLWS A NEAR CERTAINTY. SFC GUSTS OVERNIGHT WILL
BE HIGHEST AT KJST DUE TO IT/S RIDGETOP LOCATION. HRRR OUTPUT
SUGGESTS GUSTS BTWN 25-35KTS ARE POSS THERE BTWN 03Z-07Z. MUCH
LIGHTER SFC WINDS EXPECTED ELSEWHERE...WHICH WILL LEAD TO THE
LLWS.

EARLY LOW CIGS AND LINGERING DRIZZLE WILL GIVE WAY TO IMPROVING
CONDS BY LATE MONDAY AM...AS WARM FRONT LIFTS NORTH OF THE
REGION. GENERALLY VFR CONDS ARE ANTICIPATED MON AFTN. HOWEVER...A
COLD FRONT MOVING FROM THE WEST WILL BE ACCOMPANIED BY SCT LATE
DAY SHRA ACROSS THE W MTNS...POSSIBLY PRODUCING A BRIEF VSBY
REDUCTION AT KBFD OR KJST.

OUTLOOK...

TUE...NO SIG WX EXPECTED. 

WED...SNOW/LOW VSBYS POSS EASTERN PA.

THU...-SHSN/REDUCED VSBYS POSS NW MTNS. 

FRI...NO SIG WX EXPECTED.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON TODAY TO 4 AM EST TUESDAY FOR 
PAZ004>006-010-011-017-024-033.

&&

$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...DANGELO/DEVOIR/LAMBERT
SHORT TERM...DANGELO/LAMBERT
LONG TERM...RXR
AVIATION...FITZGERALD



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