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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 280735
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
235 AM EST SAT FEB 28 2015

.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL BUILD ACROSS THE AREA FOR THE
FIRST HALF OF THE WEEKEND. A LOW PRESSURE SYSTEM WILL LIFT OUT OF
THE MIDWEST...BRINGING SNOW AND MIXED PRECIPITATION TO CENTRAL
PENNSYLVANIA SUNDAY AND SUNDAY NIGHT. A STRONGER AREA OF LOW
PRESSURE WILL LIKELY TRACK WEST OF PENNSYLVANIA IN THE MIDDLE OF
THE WEEK...PRODUCING ANOTHER ROUND OF MIXED PRECIPITATION AND
RAIN IN CENTRAL PENNSYLVANIA.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
WIND HAS GONE CALM ACROSS THE NW MTNS...ALLOWING TEMPS TO PLUMMET
LATE THIS EVENING. AT 05Z...MESONET OBS INDICATE THE COLDER
VALLEYS OF THE NW MTNS HAVE ALREADY DROPPED TO ARND -15F. ACROSS
THE EASTERN HALF OF THE STATE...A LIGHT BREEZE HAS KEPT TEMPS FROM
FALLING TOO QUICKLY. HOWEVER...AS HIGH PRES BUILDS IN...EXPECT
DIMINISHING WIND AND PLUMMETING READINGS TOWARD DAWN. HAVE
TWEAKED MIN TEMPS A BIT...WITH LOWS AVERAGING FROM ARND -15F OVR
THE NW MTNS...TO 0-5F ACROSS THE LOWER SUSQ VALLEY. HOWEVER...GIVEN
THE IDEAL RAD COOLING CONDS...EXPECT A WIDE RANGE IN LOWS FROM
HILLTOPS/URBAN LOCATIONS TO NORMALLY COLDER RURAL VALLEYS.

A BIT OF THIN CIRRUS WILL OVERSPREAD THE AREA EARLY THIS AM IN
RESPONSE TO DEVELOPING WAA ALOFT. HOWEVER...IT SHOULD NOT
SIGNIFICANTLY AFFECT RAD COOLING. REC MIN FOR THE 28TH IS -18F AT
IPT AND -1F AT MDT. EVEN THE -1F AT MDT SEEMS LIKE A LONG SHOT
GIVEN CURRENT READINGS.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SUNDAY/...
FAIR AND STILL COLD WEATHER EXPECTED SATURDAY...AS SFC HIGH WILL
BE RIGHT OVERHEAD. 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 /SUNDAY 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 /07Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
LARGE 1044MB SURFACE HIGH PRESSURE AREA WILL KEEP CONDITIONS VFR
INTO SAT NIGHT...WITH LITTLE MORE THAN SOME HIGH CLOUDINESS
PASSING OVERHEAD. WINDS WILL BE LIGHT THROUGH THIS PERIOD.

CONDITIONS WILL DETERIORATE LATER SATURDAY NIGHT INTO SUNDAY...AS
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 BEGINS TO DRIVE AN
EXPANDING AREA OF WAA TYPE SNOWFALL SPREADING IN FROM THE OHIO
VALLEY. CLOUDS THICKEN AND LOWER...AND SNOW DEVELOPS FROM WEST TO
EAST ACROSS THE AREA. THE SNOW IS EXPECTED TO CHANGE TO A WINTRY
MIX ACROSS SRN PA ON SUNDAY.

THINGS SHOULD BEGIN TO IMPROVE ON MONDAY AND REMAIN GOOD INTO
EARLY TUESDAY...BEFORE THE NEXT SYSTEM PUSHES ANOTHER ROUND OF
PRECIP AND REDUCED FLYING CONDS INTO THE AREA LATER TUE INTO WED.

OUTLOOK...

SAT NIGHT-SUN...SNOW OVERSPREADING THE AREA FROM W TO E. PRECIP
SHOULD REMAIN ALL SNOW ACROSS NRN PA...WHILE MIXING W/ SLEET AND
FREEZING RAIN ACROSS THE SOUTH.

MON...CONTINUED 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.

&&

.EQUIPMENT...
KMDT AND KIPT TEMPERATURES READING FAR TOO WARM. OBSERVER AT KMDT
REPORTED 27F AS THE MAX BASED ON BACKUP OBSERVATION AND NEAREST
NEIGHBOR. PARTS ON ORDER FOR KMDT BUT KIPT TEMP SPIKE/TROUBLE IS
NEW TODAY AND WILL BE INVESTIGATED. USING 28F FOR MAX IN KIPT
FOR TODAY 2/27 BASED ON NEAREST NEIGHBOR OBSERVATIONS.

&&

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

&&

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