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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 272150
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
450 PM EST FRI FEB 27 2015

.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL BUILD ACROSS THE AREA THROUGH
THE FIRST HALF OF THE WEEKEND. A LOW PRESSURE SYSTEM WILL LIFT
OUT OF THE MIDWEST SATURDAY NIGHT AND SUNDAY...BRINGING SNOW AND
MIXED PRECIPITATION TO CENTRAL PENNSYLVANIA SUNDAY AND SUNDAY
NIGHT. A STRONGER AREA OF LOW PRESSURE WILL LIKELY TRACK WEST OF
PENNSYLVANIA LATE TUESDAY OR EARLY WEDNESDAY...PRODUCING ANOTHER
ROUND OF MIXED PRECIPITATION AND RAIN TO CENTRAL PENNSYLVANIA.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
VERY THIN SCT STRATO CU REMAINS OVER PORTIONS OF THE CENTRAL AND
SOUTH CENTRAL MOUNTAINS...LAUREL HIGHLANDS AND LOWER SUSQUEHANNA
RIVER VALLEY EARLY THIS AFTERNOON AS HIGH PRESSURE AND VERY DRY
AIR BUILDS EASTWARD REMAIN ACROSS THE REGION.

A LARGE AREA OF HIGH PRESSURE WILL BUILD EAST FROM THE OHIO
VALLEY AND CLEAR OUT MOST OR ALL OF THE STRATO CU BY
DUSK...FOLLOWED BY CLEAR SKIES THIS EVENING WITH JUST SOME THIN
CIRRUS SPREADING IN FROM THE SW.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/...
CLEARING SKIES...A CALM WIND AND SNOW COVER WILL LIKELY RESULT IN
THE LOWEST TEMPS UNTIL NEXT WINTER TONIGHT AS THE CENTER OF HIGH
PRESSURE MOVES OVER PENN.

THE IDEAL RADIATIONAL COOLING CONDS SHOULD ALLOW READINGS TO
BOTTOM OUT FROM 10-15F BELOW ZERO ACROSS THE WESTERN MTNS...TO
0-5F ABV ZERO ACROSS THE LOWER SUSQ VALLEY. THE COLDEST RURAL
VALLEYS IN NW AND NCENT PENN COULD SEE THE MERCURY SETTLE TO
AROUND -20F AT 11-12Z SATURDAY. SOME LOCATIONS ACROSS THE NW MTNS
ARE LIKELY REACH WCHILL ADVISORY CRITERIA...DESPITE A LIGHT/CALM
WIND. HOWEVER...CONFIDENCE IN WIDESPREAD APPARENT TEMPS BLW -15F
NOT THERE YET FOR AN ADVISORY.

FAIR AND STILL COLD WEATHER EXPECTED SATURDAY...AS SFC HIGH
DRIFTS OVR THE AREA. A FAST-MOVING MID LVL SHORTWAVE IS PROGGED BY
ALL MDLS TO TRACK ACROSS THE AREA LATE IN THE DAY. LOW PWAT AIR
MASS WILL PRECLUDE ANY PRECIP CONCERNS. HOWEVER...CIRRUS MAY DIM
THE SUNSHINE AT TIMES. ENS MEAN 850/925MB TEMPS REMAIN WELL BLW
NORMAL FOR THE DATE...LIKELY SUPPORTING HIGHS ONLY IN THE 20-25F
RANGE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A RELATIVELY MILD/ACTIVE SOUTHWEST FLOW ALOFT SHOULD PREVAIL
THROUGH THE PERIOD AS THE PERSISTENT UPPER RIDGE OVER THE WRN U.S.
TEMPORARILY BREAKS DOWN. NUMEROUS SHORTWAVES WITHIN THE NRN AND
SRN STREAMS WILL MOVE EAST DURING THE PERIOD PROVIDING POTENTIAL
FOR PRECIPITATION...SOME OF IT RAIN...FOR A CHANGE.

AN ARCTIC HIGH PRESSURE SYSTEM OVER CENTRAL PA AT THE START OF
THE PERIOD WILL MOVE EAST OF THE REGION BY SUNDAY NIGHT. THE
COMBINATION OF SHORTWAVE ENERGY IN THE SRN STREAM EJECTING FROM A
TROUGH AND A DIGGING NRN STREAM TROUGH MOVING SEWD FROM SOUTH
CENTRAL CANADA TOWARD THE UPPER MIDWEST SEEMS TO DRIVE AN
EXPANDING AREA OF WAA TYPE SNOWFALL SPREADING EASTWARD SUN-MON.

WHILE THERE APPEARS TO BE LITTLE INDICATION OF A STRONG SURFACE
LOW...MODELS STILL GENERATE 0.25-0.50 INCH QPF AMTS ALONG THE
BAROCLINIC ZONE. THERMAL PROFILES SEEM TO FAVOR SNOW ACROSS THE NW
1/2 OF CENTRAL PA WITH MIXED PTYPES POSSIBLE IN THE
SOUTH/SOUTHEAST. MEDIUM RANGE...ENSEMBLE AND WPC GUIDANCE SUGGEST
SUFFICIENT QP FOR A SIGNIFICANT SNOW EVENT ACROSS PART OF CENTRAL
PA. ACCORDINGLY...HAVE ISSUED A WINTER STORM WATCH ACROSS THE
NORTHWEST MOST 5 COUNTIES STARTING LATE SATURDAY NIGHT/EARLY
SUNDAY MORNING THROUGH MONDAY MORNING.

ANOTHER NRN/SRN STREAM COMBO LOOKS TO AFFECT THE REGION MID WEEK
AS ENERGY FROM THE SRN CAL UPPER LOW BEGINS TO EJECT EWD. TIMING
DIFFERENCES ARE EVIDENT WITH THE GFS MORE BULLISH ON PCPN
RETURNING EARLY TUE VS. SLOWER ECMWF (TUE NGT). MIXED PTYPE ISSUES
ARE EXPECTED AGAIN WITH THIS NEXT SYSTEM...WITH A LEAN TOWARD
RAIN AS SIGNIFICANT WARM AIR MOVES NORTH AHEAD OF THE SYSTEM.

BEHIND THE MID WEEK SYSTEM...ANOTHER PUSH OF ARCTIC AIR WILL BRING
TEMPS AND POPS BACK WELL BELOW NORMAL FOR LATE THURSDAY INTO
FRIDAY.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
THE NORTHWESTERLY BREEZE WILL DIMINISH THIS EVENING AND BECOME
LIGHT AND VARIABLE OVERNIGHT. EXPECT WIDESPREAD VFR CONDS TO
CONTINUE OVERNIGHT INTO SATURDAY.

CONDITIONS WILL DETERIORATE LATER SATURDAY NIGHT INTO SUNDAY...AS
SNOW DEVELOPS FROM WEST TO EAST ACROSS THE AREA. THE SNOW IS
EXPECTED TO CHANGE TO A WINTRY MIX ACROSS SRN PA AS THE DAY
PROGRESSES.

CONDITIONS IMPROVE MONDAY INTO EARLY TUESDAY...BEFORE THE NEXT
SYSTEM PUSHES ANOTHER ROUND OF PRECIP AND REDUCED FLYING CONDS
INTO THE AREA LATE TUES INTO WED.

OUTLOOK...

TONIGHT AND SAT...GENERALLY VFR W/ NO SIG WX EXPECTED.

SAT NIGHT-SUN...SNOW OVERSPREADING THE AREA. PRECIP SHOULD REMAIN
ALL SNOW ACROSS THE NRN MTNS...WHILE MIXING W/ SLEET AND FREEZING
RAIN CENTRAL AND SRN PA.

MON...MIXED PRECIP WITH CIG/VIS REDUCTIONS POSSIBLE...MAINLY AM.

TUE...VFR AM. MIXED PRECIP WITH CIG/VIS REDUCTIONS POSSIBLE LATE.

TUE NIGHT-WED...CIG/VIS REDUCTIONS CONTINUE IN WINTRY MIX/RAIN.
-- End Changed Discussion --

&&

.CLIMATE...
THE COLDEST FEBRUARY ON RECORD IS STILL LOOKING LIKELY. MONTHLY
MEAN TEMPERATURES THROUGH THE 26TH...IPT 18.2...MDT 20.7.

THE CURRENT RECORD COLDEST FEBRUARY..IPT 19.3...MDT 21.4 BOTH SET
IN 1934.

SO FAR...THIS MONTH IS THE THIRD COLDEST EVER AT IPT...AND FOURTH
COLDEST EVER AT MDT.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY
MORNING FOR PAZ004-005-010-011-017.

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD/GARTNER
AVIATION...EVANEGO
CLIMATE...LAMBERT