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Area Forecast Discussion
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000
FXUS61 KCTP 300919
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
519 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/...
ALL MEDIUM RANGE GUIDANCE STILL SHOWS A POTENT SHORTWAVE DIVING
SE THRU THE GRT LKS AND CARVING OUT A DEEP TROUGH OVR THE
NORTHEAST CONUS BY FRI NIGHT. TRACK OF THIS FEATURE NOW
APPEARS RELATIVELY CERTAIN BASED ON LACK OF SPREAD IN MDL
RUNS...ALL OF WHICH INDICATE A PATH ACROSS EASTERN OHIO FRIDAY PM.
BEST LG SCALE FORCING OVR PA...AS IMPLIED BY MDL 300-500MB Q-VEC
CONVERGENCE...SHOULD BE ACROSS THE WESTERN HALF OF THE STATE.
LATEST GEFS/SREF OUTPUT SUPPORT CATEGORICAL POPS ACROSS THE
ALLEGHENY PLATEAU FRI AFTN/FRI NIGHT AND ONLY CHC POPS ACROSS THE
SUSQ VALLEY. LACK OF DEEP MOISTURE SHOULD RESULT IN FAIRLY LIGHT RAINFALL
WITH THIS FEATURE...PERHAPS UP TO A QUARTER INCH OVR THE W MTNS.

RISK OF SNOW OVR THE ALLEGHENIES FRIDAY NIGHT APPEARS LOW GIVEN
LATEST OPER MDL SOUNDINGS...AS WELL AS GEFS/SREF PROBS. HAVE
REMOVED CHC OF SNOW AND RAISED OVERNIGHT LOWS TO ABOVE FREEZING
EVERYWHERE FRI NIGHT.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
ALL MED RANGE GUIDANCE CUTS OFF UPPER LOW SOUTH OF PA SATURDAY.
REMNANTS OF ASSOC CLIPPER LOW SHOULD DIE OVR THE CENTRAL
APPALACHIANS AS ENERGY IS TRANSFERRED TO DEVELOPING COASTAL LOW
NR CAPE HATTERAS. AS COASTAL STORM LIFTS NE...A TIGHTENING
PRESSURE GRADIENT AND NW FLOW WILL DRAW MUCH COLDER/DRIER AIR INTO
PA. 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 WILL LIKELY PRODUCE SCT LAKE EFFECT SNOW
SHOWERS ACROSS THE ALLEGHENY PLATEAU SATURDAY NIGHT. GIVEN DRYNESS
OF AIR MASS MOVING IN...DON/T EXPECT ANY SIG ACCUMS...BUT A
COATING OF SNOW DOES APPEAR POSSIBLE OVR THE W MTNS.

TEMPS THIS WEEKEND WILL ALMOST CERTAINLY BE THE COLDEST YET THIS
SEASON. ENSEMBLE MEAN 8H TEMPS POINT TOWARD DAYTIME HIGHS FROM
THE U30S-L40S OVR THE ALLEGHENIES TO 45-50F ACROSS THE LOWER SUSQ
VALLEY. 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. DEEP UPPER TROF WILL LIFT OUT QUICKLY EARLY NEXT
WEEK...ALLOWING A MUCH MILDER RETURN SW FLOW TO OVERSPREAD THE
REGION. TEMPS LIKELY TO RETURN TO ABV NORMAL READINGS BY TUESDAY.  

&&

.AVIATION /09Z 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...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...STEINBUGL



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