Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 030337
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1037 PM EST MON MAR 2 2015

.SYNOPSIS...
HIGH PRESSURE WILL PASS THROUGH THE REGION OVERNIGHT. AN AREA OF
LOW PRESSURE AND FRONTAL SYSTEM WILL TRACK WEST OF PENNSYLVANIA
LATE TUESDAY AND EARLY WEDNESDAY...BRINGING ANOTHER ROUND OF
SIGNIFICANT WINTRY/MIXED PRECIPITATION TO THE REGION TUESDAY
AFTERNOON INTO EARLY TUESDAY NIGHT. THE PRECIPITATION WILL LIKELY
TURN TO RAIN ACROSS SOUTHERN SECTIONS EARLY WEDNESDAY. COLDER
TEMPERATURES WILL FOLLOW FOR THE LATTER PART OF THE WEEK. SNOW IS
AGAIN POSSIBLE WEDNESDAY NIGHT INTO THURSDAY AS A WAVE OF LOW
PRESSURE RIPPLES ALONG THE FRONT DRAPED JUST TO OUR SOUTH. HIGH
PRESSURE AND COLD AIR WILL RETURN FOR FRIDAY INTO THE FIRST PART
OF THE WEEKEND.

&&

.NEAR TERM /UNTIL 10 AM TUESDAY MORNING/...
WINDS LIGHT OVER WESTERN PA. AS THE HIGH SLIDES IN FROM THE
WEST...WE TOO SHOULD GO LIGHTER ON THE WINDS. EXPECT SOME CHILLY
READINGS AS DEWPOINTS ARE QUITE LOW. SKIES WILL NOT GET REALLY
CLOUDY UNTIL AFTER SUNRISE...BUT WILL GET CLOUDY IN A HURRY AS THE
WARM ADVECTION BRINGS IN QUITE A BIT OF MOISTURE FOR WINTER.
HOWEVER...IT IS VERY DRY AT THE SFC AND EXPECT ALL PRECIP TO HOLD
OFF UNTIL AFTER 15Z/10AM.

&&

.SHORT TERM /10 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
CONDITIONS WILL GO DOWNHILL FAIRLY QUICKLY ON TUESDAY WITH
MOISTURE FROM BAJA MONSOONAL FLOW ADVECTING THROUGH THE OHIO
VALLEY AND ARRIVING INTO THE ALLEGHENIES BY LATE MORNING IN THE
FORM OF SNOW INITIALLY...SPREADING EASTWARD ACROSS MY CWA THROUGH
THE MIDDAY AND EARLY AFTERNOON HOURS.

VERY MILD BOUNDARY LAYER FLOW WILL BRING A QUICK MIX AND EVENTUAL
CHANGEOVER TO FREEZING RAIN FOR ALL AS THE DAY PROGRESSES. THERE
MAY BE A COMPLETE CHANGEOVER TO RAIN ACROSS THE FAR SOUTH AND
SOUTHEAST. CONSENSUS BLEND OF 12Z OPERATIONAL MODELS AND ENS
GUIDANCE IS CONSISTENT WITH PREVIOUS SOLUTIONS FOR AN INITIAL FEW
TO SEVERAL HOUR PERIOD OF SNOW/SLEET TUESDAY...FOLLOWED BY A
SIGNIFICANT BOUT OF MIXED PRECIP/FREEZING RAIN TUESDAY AFTERNOON
THROUGH EARLY TUESDAY NIGHT. OVERALL IT APPEARS THAT PROLONGED ICE
ACCRETION IS THE MAIN THREAT...PRECEDED BY THE COATING TO 1 INCH
OF SNOW FAR SOUTH AND 1 TO 2 INCHES OF SNOW IN MOST AREAS (WITH UP
TO 3 INCHES NORTH). THE NORTH MAY NOT COMPLETELY MIX OUT...AND
EXPECT AREAS OF FREEZING RAIN TO PERSIST THERE THROUGH THE PRE
DAWN HOURS ON WEDNESDAY. ICE ACCUMS SHOULD BE ON THE ORDER OF
0.10-0.20 OF AN INCH ACROSS THE NCENT MTNS OF PA...WITH LESSER
AMOUNTS IN MOST PLACES TO THE SOUTH OF INTERSTATE 80.

IN COLLABORATION WITH ALL SURROUNDING OFFICES...WINTER WEATHER
ADVISORIES HAVE BEEN ISSUED FOR A PERIOD OF SNOW/SLEET ACCUM
FOLLOWED BY FREEZING RAIN...GENERALLY FROM MIDDAY TUESDAY THROUGH
THE EARLY MORNING HOURS ON WEDNESDAY.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AN ACTIVE LATE-WINTER PATTERN WILL AFFECT CENTRAL PA THROUGH
MIDWEEK FOLLOWED BY WHAT IS HOPEFULLY THE LAST SHOT OF ARCTIC AIR
FOR THE SEASON THURSDAY INTO FRIDAY. THE PATTERN SHOULD DRY OUT
LATE IN THE WEEK THROUGH THE UPCOMING WEEKEND WITH HIGH PRESSURE
IN CONTROL MOST OF THE TIME. THE GENERAL MODEL CONSENSUS IS TO
MAINTAIN A RIDGE IN THE WEST AND TROUGH IN THE EAST...LIMITING
TEMPERATURE MODERATIONS TO NO BETTER THAN CLIMATE NORMALS.

MODELS SHOW AN ACTIVE PCPN ZONE EXTENDING FROM THE SRN PLAINS
ENEWD INTO THE NRN MID ATLANTIC STATES...IN BTWN A POSITIVELY
TILTED TROUGH PUSHING THROUGH THE PLAINS/MIDWEST/GREAT LAKES AND
ABOVE NORMAL RIDGING FROM THE GOMEX INTO THE WRN ATLANTIC OCEAN.
SEVERAL WAVES OF LOW PRESSURE ARE FCST TO MOVE ALONG A SW-NE
ORIENTED COLD FRONT WHICH SHOULD SLOWLY PROGRESS EWD TOWARD THE
COAST WED-THUR AS NRN STREAM ENERGY CROSSES THE GREAT LAKES. THERE
ARE SOME DIFFERENCES WITH MODEL QPF BUT THE CONSENSUS POINTS
TOWARD THE SRN PA FOR THE HIGHEST PCPN AMTS. USED A MULTI MODEL
BLEND WITH PSEUDO BIAS CORRECTION FACTOR TO DERIVE GRIDDED QPF
AMTS WHICH CONSERVATIVELY RANGE FROM 0.25 TO 0.75 INCHES ACROSS
THE SRN 1/2 OF THE CWA. THE COLUMN WILL BE IN A STATE OF
TRANSITION AND COOLING FROM NW TO SE WED-WED NGT AS THE COLD FRONT
PUSHES EAST. THIS SHOULD SUPPORT A GENERAL TRANSITION FROM RAIN TO
SNOW ACROSS THE CWA. WITH A DECENT AMOUNT OF MSTR AVAILABLE/STRIPE
OF ABOVE NORMAL PW LOCATED JUST SOUTH OF PA...THE POTENTIAL EXISTS
FOR MODERATE TO HEAVY SNOW OVER THE SRN PORTIONS OF THE AREA.
HOWEVER GIVEN THE UNCERTAINTY AT DAY 3-4 RANGE IN THE FRONTAL
WAVES AND THERMAL PROFILES IN A STATE OF FLUX GOING FROM WARM TO
COLD...CONFIDENCE IN BIG AMOUNTS IS QUESTIONABLE. FOR NOW THE DAY
3+4 NUMBERS RANGE FROM 0-2" NORTH OF I-80...2-4" FROM I80 TO THE
PA TURNPIKE/I-81 AND AMOUNTS IN EXCESS OF 4" POSSIBLE ALONG/S OF
THE TURNPIKE/I-81. THIS IS SUBJECT TO CHANGE AS ANY SLIGHT SHIFT
IN THE QPF AXIS IS PLAUSIBLE AT THIS POINT. THE TAKEAWAY HERE IS
THAT WINTER WX WILL LKLY CONTINUE TO IMPACT THE AREA THROUGH
MIDWEEK WITH THE GREATEST RISK FOR HEAVY SNOW OVER THE SRN
PORTIONS OF THE CWA.

WHAT IS HOPEFULLY THE LAST SHOT OF ARCTIC AIR SHOULD ARRIVE BEHIND
THE COLD FRONT THURSDAY WITH SINGLE DIGIT LOWS +/- OF FRIDAY
MORNING. MAY BE THE COLDEST MORNING UNTIL NEXT WINTER. SOME SNOW
SHOWERS ARE POSSIBLE OVER THE WEEKEND WITH A REINFORCING COLD
FRONT. TEMPS WILL REMAIN AT OR BELOW AVG THROUGH THE PERIOD.

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
MINOR ADJUSTMENTS MADE TO 03Z TAFS.

EARLIER DISCUSSION BELOW.

LOOKING AT JUST A FEW CLDS OVERNIGHT WITH VFR CONDITIONS.

WINDS WILL DIE DOWN IN ANOTHER HOUR OR TWO.

A FAST MOVING SYSTEM MOVING ACROSS THE GREAT LAKES WILL
PULL WARM AIR INTO THE AREA LATE TUE. SNOW WILL QUICKLY
MOVE IN DURING THE AFTERNOON AND MIX WITH AND CHANGE TO
A MIXTURE OF FREEZING RAIN...SNOW...AND SLEET BY LATE
TUE AFT AND EARLY EVENING...BEFORE CHANGING TO RAIN LATE
TUESDAY NIGHT INTO EARLY WED.

A FEW RAIN SHOWERS WILL BE ACROSS THE AREA ON WED.

AS COLDER AIR WORKS BACK TO THE SOUTH LATE WED INTO EARLY
THU...LOW PRESSURE MOVING NE ALONG THE FRONT WILL LIKELY
RESULT IN A NASTY MIXTURE OF PRECIPITATION. POTENTIAL
IS THERE FOR HEAVY WET SNOW AND SIGNIFICANT FREEZING RAIN
AS WELL.

IMPROVING CONDITIONS FOR LATE THU.

OUTLOOK...

WED...CIG/VIS REDUCTIONS CONTINUE IN WINTRY MIX/RAIN.

THU...SLOWLY IMPROVING CONDITIONS...LINGERING MVFR NW AND SE.

FRI-SAT...MAINLY VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 PM TUESDAY TO 7 AM EST
WEDNESDAY FOR PAZ006-011-012-018-037-041-042.
WINTER WEATHER ADVISORY FROM 1 PM TUESDAY TO 4 AM EST
WEDNESDAY FOR PAZ004-005-010-017-024>026-033>035.
WINTER WEATHER ADVISORY FROM 3 PM TUESDAY TO 4 AM EST
WEDNESDAY FOR PAZ019-027-028-036-045-046-049>053-056>059-
063>066.

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO/DEVOIR
LONG TERM...STEINBUGL
AVIATION...MARTIN



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