Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 021911
AFDCTP

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

.SYNOPSIS...
HIGH PRESSURE WILL MOVE ACROSS THE REGION TONIGHT. 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...AND CHANGING TO RAIN BY EARLY
WEDNESDAY ACROSS SOUTHERN SECTIONS. COLDER TEMPERATURES WILL
FOLLOW FOR THE LATTER PART OF THE WEEK...AND ANOTHER ROUND OF
PRECIPITATION MAY FALL AS SNOW WEDNESDAY NIGHT INTO THURSDAY AS A
SECOND WAVE OF LOW PRESSURE RIPPLES ALONG THE FRONT. HIGH PRESSURE
AND TRANQUIL CONDITIONS WILL RETURN FOR FRIDAY INTO THE FIRST PART
OF THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
WATER VAPOR LOOP SHOWS SHARP UPPER TROF HAS MOVED OFF THE NORTHERN
MID ATLANTIC COAST AND SHORTWAVE RIDGING IS BUILDING OVER THE OHIO
VALLEY. SCT-BKN STRATUS IS DECREASING OVER THE NORTHWEST AND WEST
CENTRAL MOUNTAINS WHILE THE SOUTHEAST ANDSOUTH CENTRAL MOUNTAINS
ARE CLEAR. WINDS ARE GUSTY THROUGHOUT...WITH METARS INDICATING 25
TO 28 KT GUSTS ACROSS MOST OF CENTRAL PA.

HIGH PRESSURE WILL BUILD ACROSS THE REGION TONIGHT BEFORE MOVING
OFFSHORE EARLY TUESDAY. WINDS WILL SLACKEN NICELY BY LATE EVENING
ACROSS MOST OF CENTRAL PA...LEADING TO A CHILLY NIGHT. MINS WILL
RANGE FROM THE SINGLE DIGITS ABOVE ZERO NORTHWEST TO THE MID TEENS
SOUTH.

&&

.SHORT TERM /TUESDAY 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 SUNDAY/...
RAIN SHOULD TAPER OFF TO SCATTERED SHOWERS WITH THE PASSAGE OF
THE TRAILING COLD FRONT EARLY WEDNESDAY.

FOR WED...TOOK SNOW SHOWERS OUT OF THE NW. TIGHT THICKNESS PATTERN
ACROSS THE AREA...SUPPORT A LARGE TEMPERATURE GRADIENT FROM NW PA
TO SE PA. THERE COULD BE A FEW SHOW SHOWERS ACROSS THE FAR
NW...BUT IT LOOKS LIKE MAINLY NW OF OUR AREA. LEFT POPS UP...THINK
FRONT WILL BE SLOW TO MOVE OUT.

IN FACT...THE 00Z EC AND FRESH IN 06Z NAM BOTH HIGHLIGHT A WEAK
WAVE OF LOW PRESSURE...AND EXTENSIVE RIBBON OF DEEP MOISTURE...
STREAMING NE ALONG THE NEARLY STALLED-OUT FRONT /JUST SOUTH OF
THE MASON/DIXON LINE...AND OHIO RIVER/. THIS WILL GREATLY
COMPLICATE THE WEATHER FOR THE LATE WED INTO THURSDAY TIMEFRAME
WITH THE POTENTIAL FOR A LIGHT-MDT SNOWFALL ACROSS SE THIRD TO HALF
OF PENN.

AFTER THE AFOREMENTIONED WAVE OF LOW PRESSURE SCOOTS BY TO OUR
NE...A PUSH OF ARCTIC AIR WILL BRING TEMPS AND POPS BACK WELL
BELOW NORMAL FOR LATE THURSDAY INTO FRIDAY. THE ONLY GOOD THING
SEEMS TO BE EACH ARCTIC SHOT IS A LITTLE LESS POTENT THAN THE LAST
AS WE LEAVE THE RECORD COLD OF FEBRUARY BEHIND.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
WNW FLOW OVER CENTRAL PA WITH WINDS 10-20 MPH WITH GUSTS TO
AROUND LOCALLY OVER 30 MPH. MVFR CIGS AND OROGRAPHICALLY INDUCED
LIGHT SNOW/FLURRIES WILL DIMINISH BY LATE AFTERNOON. VFR CONDS
PREVAILING ELSEWHERE.

WINDS GRADUALLY DIMINISH TONIGHT AS WE/LL SEE A BRIEF RESPITE
UNTIL THE NEXT SYSTEM PUSHES ANOTHER ROUND OF PRECIPITATION AND
REDUCED FLYING CONDITIONS INTO THE AREA LATER TUESDAY AND
WEDNESDAY.

OUTLOOK...

TUE...VFR AM. MIXED WINTRY PRECIP WITH CIG/VIS REDUCTIONS AND
LLWS DEVELOPING LATE AFT AND LASTING THROUGH TUE NIGHT.

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...DEVOIR
NEAR TERM...DEVOIR
SHORT TERM...DEVOIR
LONG TERM...LAMBERT/MARTIN
AVIATION...DEVOIR/RXR


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