Area Forecast Discussion
Issued by NWS State College, PA

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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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