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Area Forecast Discussion
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000
FXUS61 KCTP 271658
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1158 AM 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 PRES SYSTEM WILL LIFT OUT OF
THE MIDWEST LATE IN THE WEEKEND...PASSING OVER THE REGION SUNDAY
NIGHT. A STRONGER AREA OF LOW PRESSURE WILL LIKELY TRACK WEST OF
PENNSYLVANIA LATE TUESDAY OR EARLY WEDNESDAY.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
LATE MORNING VIS SATL AND RADAR LOOP SHOWS THAT ONLY AREAS OF
SHALLOW SCT-BKN STRATO CU REMAIN ACROSS THE REGION AS THE
EARLIER...HIGHLY-LOCALIZED AND ENHANCED AREAS OF FGEN SNOWS
QUICKLY DISSIPATED BETWEEN 12-14Z.

EXPECT JUST A FEW FLURRIES TO FALL FROM THE COLD SHALLOW STRATO CU
THIS AFTERNOON WITH HIGH TEMPS ONLY IN THE UPPER SINGLE DIGITS TO
LOWER TEENS ACROSS THE NW MTNS AND LAUREL HIGHLANDS...AND UPPER
TEENS TO MID 20S FROM THE CENTRAL MTNS SE INTO THE LOWER SUSQ
VALLEY.

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 THURSDAY/...
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. AN ARCTIC HIGH PRESSURE SYSTEM OVER
CENTRAL PA AT THE START OF THE PERIOD WILL RETREAT INTO ATLANTIC
CANADA BY SUNDAY NIGHT. THE COMBINATION OF SHORTWAVE ENERGY IN THE
SRN STREAM EJECTING FROM A DSW 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 BEHIND THE SOUTHERLY RETURN FLOW INTO
A RETREATING COLD SECTOR ASSOCD WITH THE DEPARTING ARCTIC HIGH.
THE PCPN SHOULD BE ENHANCED ALONG AN EXPANDING BAROCLINIC ZONE
ACROSS THE CENTRAL AND EASTERN US...AS UPPER RIDGING BUILDS OVER
THE SE U.S.

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 IN THE SOUTH/SOUTHEAST.
PRELIMINARY 24HR SNOW/ICE AMOUNTS WERE DERIVED USING A MULTI
MODEL QPF BLEND WITH PSEUDO INTERNAL BIAS CORRECTION FACTOR AND
WPC WWD. THIS RESULTS IN ADVY LEVEL SNOWFALL OVER THE NW 1/2 AND
0.10 INCH ICE/ZR OVER THE LWR SUSQ VLY. CONFIDENCE IN THE AMTS IS
AVG AT BEST GIVEN UNCERTAINTY IN QPF AND LOW-LEVEL TEMPERATURES.
THE LACK OF A DEFINED SFC CYCLONE ALSO RAISES SOME REG FLAGS.

ANOTHER COLD HP SYSTEM BUILDS INTO THE REGION MON-TUE WITH ANOTHER
SW FLOW WAA MSTR SURGE ALONG BAROCLINIC FRONTAL ZONE LKLY
IMPACTING THE AREA INTO THE MIDDLE OF NEXT WEEK. 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.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AREAS OF MVFR CIGS /IN THE FORM OF SHALLOW STRATO CU CLOUDS/ WILL
CONTINUE THIS AFTERNOON...BEFORE A LARGE AREA OF HIGH PRESSURE
CURRENTLY OVER THE OHIO VALLEY BUILDS EAST OVER PENNSYLVANIA
TONIGHT. WINDS FOR THE AFTERNOON HOURS WILL BE MAINLY W/NW AT
7-10 KTS.

EXPECT WIDSPREAD VFR AFTER DUSK WITH WINDS GOING LIGHT AND
VARIABLE.


OUTLOOK...

TONIGHT AND SAT...NO SIG WX EXPECTED.

SUN...SNOW SPREADING ACROSS THE WRN MTNS DURING THE PREDAWN HOURS
SUNDAY. PRECIP SHOULD STAY ALL SNOW ACROSS THE NRN MTNS OF PENN.
SNOW EXPECTED TO MIX WITH SLEET AND FREEZING RAIN CENTRAL AND SERN
PENN...AND POSSIBLY CHANGE TO ALL RAIN ACROSS THE SW PART OF THE
STATE LATER SUNDAY AFTERNOON AND NIGHT.

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

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

&&

.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...
NONE.

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD/STEINBUGL
AVIATION...RXR
CLIMATE...



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