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Area Forecast Discussion
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000
FXUS61 KCTP 300826
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
426 AM EDT THU OCT 30 2014

.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY THIS MORNING WILL MOVE INTO
THE APPALACHIANS TONIGHT. A VIGOROUS UPPER LEVEL TROUGH DIGGING
THROUGH THE CAROLINAS WILL SUPPORT THE DEVELOPMENT OF A STRONG
COASTAL STORM TRACKING JUST EAST OF THE NEW ENGLAND BENCHMARK THIS
WEEKEND. THIS WILL LEAD TO A BRISK NORTH NORTHWEST WIND WITH MUCH
COLDER AIR SUPPORTING SNOW SHOWERS OVER THE WESTERN ALLEGHENIES
SATURDAY NIGHT. HIGH PRESSURE WILL RETURN TO THE AREA BEHIND THE
DEPARTING STORM SYSTEM ON MONDAY WITH MODERATING TEMPERATURES INTO
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
PATCHY DENSE FOG OVR PORTIONS OF THE LOWER SUSQ VALLEY SHOULD
LIFT OVER THE NEXT 1-2 HOURS AS A LIGHT NW WIND ADVECTS DRIER AIR
INTO THE AREA. 

COOL AIR SPREADING DOWNWIND OF THE LOWER GREAT LAKES ALONG WITH
WEAK UPSLOPE FLOW IS SUPPORTING AN EXPANSIVE AREA OF STRATOCU
CLOUDS ACROSS THE NW ALLEGHENIES. THESE CLOUDS WILL PREVAIL
THROUGH THE MORNING AS THE LLVL MSTR GETS TRAPPED UNDER THE
SUBSIDENCE INVERSION ASSOCIATED WITH SFC HIGH MIGRATING SLOWLY
EWD FROM THE OH VLY. MDL DATA SUGGESTS BINOVC THIS AFTN WHICH MAY
BE A LITTLE TOO OPTIMISTIC. DOWNSLOPE FLOW SHOULD LEAD TO MORE SUN
EAST OF THE ALLEGHENY FRONT.

SHORTWAVE RIDGING ALOFT AND HIGH PRES AT THE SFC WILL COMBINE TO
BRING DRY WX TO CENTRAL PA FROM THIS AFTN INTO TONIGHT. HIGH TEMPS
WILL RANGE FROM THE MID 40S IN THE NW TO NEAR 60F IN THE LWR SUSQ.
AMPLIFYING UPPER TROUGH PIVOT INTO THE UPPER GREAT LAKES BY 12Z
FRI WITH A SFC LOW DEVELOPING NEAR LAKE HURON. MDL CONSENSUS
SUPPORTS A SCHC OF SHOWERS OVER FAR NW PA BY THE END OF THE PD.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
THE BIG STORY THROUGH THE LONG TERM PERIOD REMAINS THE TRACK OF
THE LARGE UPPER LEVEL LOW THAT WILL PROGRESS THROUGH THE GREAT LAKES
REGION ON FRIDAY...AND ITS PROGRESSION EASTWARD THIS WEEKEND.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
ALL MEDIUM RANGE GUIDANCE STILL SHOWS A POTENT SHORTWAVE DIVING
SE FROM CANADA AND CARVING OUT A DEEP TROUGH OVR THE NORTHEAST
CONUS BY SATURDAY. THE GFS ENSEMBLES VARY ON THE STRENGTH AND
POSITION OF THIS LOW...THROUGH ALL SHARE SIMILAR TIMING. THE
OPERATIONAL GFS AND EC ARE IN LINE WITH ONE ANOTHER AND HAVE THE
UPPER LOW DIG SOUTH OF THE REGION AND ACTUALLY MOVES THROUGH THE
CAROLINAS BEFORE MOVING OFF COAST. THE EC HAS TRENDED TOWARDS THE
GFS...AND BOTH HAVE THE LOW FURTHER EASTWARD INTO THE ATLANTIC
BEFORE IT TRAVERSES NORTHWARD. THE ASSOCIATED SFC CLIPPER LOW IS
PROGGED TO TRACK ACROSS EASTERN OHIO/WESTERN PA LATE FRIDAY AND
FRIDAY NIGHT...BRINGING THE BEST CHANCE OF PRECIP TO THAT AREA.
BOTH GEFS AND OPER ECMWF/CANADIAN MDLS ALL POINT TOWARD A MAINLY
RAIN EVENT FRIDAY. HOWEVER...AS UPPER LOW CUTS OFF SOUTH OF PA
EARLY SATURDAY...THERMAL PROFILES...COUPLED WITH MOIST EASTWARD
UPSLOPE FLOW MAY BECOME COLD ENOUGH TO PRODUCE A LIGHT COATING OF
SNOW ACROSS THE HIGH TERRAIN OF THE ALLEGHENIES. EXPECT A
RAIN...SNOW MIX POSSIBLE THROUGH THIS TIMEFRAME...AND ANY SNOWFALL
WILL BE WET.

AS THE DEVELOPING COASTAL LOW MOVES UP THE COAST LATE
SATURDAY...A TIGHTENING PRESSURE GRADIENT AND NW FLOW WILL DRAW
MUCH COLDER/DRIER AIR INTO THE REGION. 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 MAY PRODUCE
LAKE EFFECT SNOW SHOWERS ACROSS THE NW MTNS SATURDAY NIGHT...EARLY
SUNDAY MORNING. ESPECIALLY GIVEN THE STRONG...MOIST 850MB FLOW.

TEMPS THIS WEEKEND WILL ALMOST CERTAINLY BE THE COLDEST YET THIS
SEASON. ENSEMBLE MEAN 8H TEMPS POINT TOWARD DAYTIME HIGHS FROM
THE UPPER 30S OVR THE ALLEGHENIES TO THE 40S ELSEWHERE. THE
COLDEST NIGHT OF THIS OUTBREAK WILL LIKELY BE SUNDAY NIGHT...WHEN
SFC HIGH BUILDS OVR THE REGION. 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/MONDAY...WHEN
ALL GUIDANCE BUILDS SFC HIGH AND ASSOC DRY AIR MASS ACROSS PA. AN
APPROACHING COLD FRONT WILL BRING THE NEXT CHC OF SHRA BY
MIDWEEK.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
THE MAIN AVN CONCERN NEAR TERM IS VLIFR FOG AT LNS/MDT WITH CONDS
BELOW AIRFIELD MINS. WILL SHOW 2-3HR PERIOD OF THESE CONDS IN 06Z
TAFS BEFORE SIGNALING SOME IMPROVEMENT BY 09Z AS A LGT NW WIND
ADVECTS DRIER AIR INTO THE AREA. ELSEWHERE MVFR CIGS WILL PREVAIL
AT BFD DUE TO COOL NW FLOW DOWNWIND OF LAKE ERIE. REMAINING SITES
SHOULD STAY MAINLY VFR WITH SCT-BKN HI-BASED SC DECK ALTHOUGH JST
COULD DROP TO MVFR LATER THIS MORNING. WEAK UPSLOPE FLOW UNDER SFC
HIGH BUILDING EWD SUGGESTS LOW CIGS WILL CONTINUE DURING THE DAY
AT BFD/JST WITH VFR CONDS EXPECTED EAST OF THE ALLEGHENY FRONT.

OUTLOOK...

FRI...VFR/MVFR EARLY WITH RAIN SHOWERS DEVELOPING WRN SXNS BY EVE.
REDUCED CONDS LKLY FRI NIGHT WEST-CENTRAL 1/2 OF AIRSPACE WITH
RAIN SHOWERS MIXING WITH/CHANGING TO SNOW SHOWERS WESTERN 1/3.

SAT...MVFR/IFR WITH SCATTERED RAIN/SNOW SHOWERS WEST. VARYING
CONDS FROM VFR-MVFR CENTRAL/EAST WITH OCNL -SHRA. N-NW WIND GUSTS
25-40 MPH.

SUN...RAIN/SNOW SHOWERS ENDING WEST. LOW CIGS WEST BECOMING
VFR. GUSTY NNW WINDS GRADUALLY DECREASING AREA-WIDE.

MON...VFR.

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD/STEINBUGL
SHORT TERM...DEVOIR/FITZGERALD
LONG TERM...FITZGERALD/CERU
AVIATION...STEINBUGL



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