Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 280032 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 732 PM EST FRI FEB 27 2015 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 8 PM THIS EVENING/...
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645 PM UPDATE... CLEAR SKIES AND LIGHT NW WINDS. HIGH PRESSURE NOT QUITE OVERHEAD BUT MAY BE BY 12Z. THE WINDS SHOULD GO LIGHTER. ONLY THIN CIRRUS SHOULD MOVE IN FROM THE SW OVERNIGHT. DEWPOINTS ARE HEADED DOWNWARD FAST WITHOUT MELTING/EVAP FROM THE SUNLIGHT. ALL THIS SHOULD ALLOW THE TEMPS TO PLUMMET ONCE AGAIN INTO THE NEGATIVE DOUBLE DIGITS IN THE NWRN MTNS AND SUB- ZERO ACROSS MOST OF THE REST OF THE AREA. REC MIN FOR THE 28TH IS -18F AT IPT AND ONLY -1F AT MDT. MDT LOOKS RIPE...BUT WON/T GO QUITE THAT COLD - YET. WILL REVISIT IN 3 HOURS. PREV... 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.
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&& .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 /01Z SATURDAY THROUGH WEDNESDAY/... THE NORTHWESTERLY BREEZE WILL DIMINISH BECOME LIGHT AND VARIABLE OVERNIGHT. EXPECT WIDESPREAD VFR CONDS TO CONTINUE OVERNIGHT AND THROUGH SATURDAY. CONDITIONS WILL DETERIORATE LATER SATURDAY NIGHT INTO SUNDAY...AS 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. CONDITIONS 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 TUES INTO WED. OUTLOOK... OVERNIGHT INTO SAT...GENERALLY VFR. NO SIG WX EXPECTED. SAT NIGHT-SUN...SNOW OVERSPREADING THE AREA. 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. && .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...
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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.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR PAZ004-005-010-011-017. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...EVANEGO CLIMATE...LAMBERT EQUIPMENT...DANGELO

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