Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 011058 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 558 AM EST SUN MAR 1 2015 .SYNOPSIS... WEAK LOW PRESSURE AND A DISTURBANCE AT UPPER LEVELS OF THE ATMOSPHERE WILL TRACK NORTHEAST UP THE OHIO VALLEY AND CROSS PENNSYLVANIA TODAY. THIS PAIR OF WEATHER FEATURES WILL BRING PERIODS OF LIGHT TO BRIEFLY MODERATE SNOW...THEN SOME MIXED PRECIPITATION TO SOUTH-CENTRAL PA AND THE LOWER SUSQ VALLEY LATE TODAY AND TONIGHT. HIGH PRESSURE WILL BRING FAIR AND COLD CONDITIONS TO REGION MONDAY AND MONDAY NIGHT. A STRONGER AREA OF LOW PRESSURE WILL LIKELY TRACK WEST OF PENNSYLVANIA LATE TUESDAY AND EARLY WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE LEADING EDGE OF THE LARGE SHIELD OF LIGHT SNOW HAS SPREAD EAST TO THE SUSQUEHANNA VALLEY AS OF 10Z. LATEST 00Z/06Z OPER MODELS AND 03Z SREF ARE QUITE CONSISTENT WITH A GENERAL LIGHT TO MODERATE SNOWFALL ACROSS THE REGION TODAY INTO EARLY TONIGHT FROM APPROX 2-4 TENTHS OF LIQ EQUIV QPF. MULTI MODEL BLEND ALSO CONTINUES TO DISPLAY THE THREAT FOR UP TO AROUND 0.25 INCH OF ICE FROM FREEZING RAIN LATER THIS AFTERNOON INTO THIS EVENING ACROSS THE LOWER SUSQ VALLEY...MAINLY TO THE SOUTHEAST OF THE I-81 CORRIDOR...WITH THE BEST CHC BEING CLOSE TO THE PA/MD BORDER. SINCE THE EVENT WILL START AS SEVERAL HOURS OF SNOW THEN MIX WITH/CHANGE TO SLEET AND FZRA WITH ICE AMOUNTS STILL UNCERTAIN AND BORDERLINE FOR A WARNING...WE WILL CONTINUE TO HOLD OFF ON ANY UPGRADES TO WINTER STORM/ICE STORM WARNINGS AT THIS TIME. ADDITIONAL HIGH RES MODELS THIS MORNING WILL LIKELY PROVIDE BETTER DETAIL TO MAKE THE DECISION REGARDING POTENTIAL ICE AMOUNTS AND LOCATIONS. CONSISTENCY OF THE PAST SEVERAL MODEL RUNS AND ENSEMBLES WITH RESPECT TO PTYPE INDICATES THAT THE BULK OF THIS WINTRY EVENT WILL FALL AS SNOW TO THE NORTH OF THE RT22/322 CORRIDOR IN CENTRAL PENN. TEMPS WILL BE NEARLY STEADY IN THE TEENS TO AROUND 20F THROUGH 13Z...THEN SLOWLY RISE TO A LATE DAY HIGH IN THE UPPER 20S ACROSS THE CENTRAL AND NORTHERN MTNS...AND LOWER TO MID 30S ACROSS THE LOWER SUSQ VALLEY AND LAUREL HIGHLANDS RESPECTIVELY. WINDS WILL SOUTHEAST TO SOUTH AT 5-8 KTS IN MOST PLACES THROUGH TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... THE VERY WEAK LOW DEVELOPING ON THE DELMARVA AND RUSHING OFF SHORE LATE TODAY INTO TONIGHT WILL ENHANCE THE MIXED PRECIP OR FREEZING RAIN RATES OVER THE SERN COS FOR UP TO SEVERAL HOURS /BETWEEN 19Z-00Z/. VERY INTERESTING PART OF THE FORECAST WILL BE THE SNOW TYPE. THERE IS A REALLY GOOD SIGNAL IN THE UPPER PART OF THE CLOUDS IN THE MIDDLE OF THE DAY WHERE THE BEST VERTICAL MOTION IS SQUARELY IN THE PREFERRED DENDRITIC GROWTH ZONE AROUND -15C. THEN...IT FALLS THROUGH A HIGHLY MOIST/SATURATED COLUMN AND GETS ONLY CLOSE TO MELTING INMOST PLACE. THIS COULD MAKE SOME GIANT BUT WET FLAKES. THUS...A HIGH WATER CONTENT AND HEAVIER SNOW. THE SNOW PHYSICS...THE WINDS ALOFT AND SFC TEMPS ALL WILL PULL THE SNOW ACCUMS ONE WAY AND ANOTHER. HOWEVER...TEMP PROFILES LOOK PRETTY SIMILAR TO PAST WEEKENDS VERY SIMILAR STORM. MANY SIMILARITIES EXIST WITH THAT PREV STORM...BUT THE TEMPS APPEAR JUST SLIGHTLY COLDER. THINKING THAT WE WILL GET BIGGER FLAKES BUT END UP WITH THE SAME WATER CONTENT AND SLIGHTLY HIGHER SNOW ACCUMS OVER MOST OF THE AREA. GREATEST FCST BUST POTENTIAL APPEARS TO EXIST IN THE SE...WHERE IF THERE ENDS UP BEING NO TURNOVER TO MIXED PRECIP/ZR...IT WILL MEAN THAT THE 0.6 INCHES OF WATER PROGGED THERE MAY NUDGE THEM NEAR WARNING AMOUNTS. EVEN THIS SEEMS VERY SIMILAR TO THE FEB 21ST. PRECIP LOOKS TO TAPER OFF IN ALL AREAS DURING THE LATE EVENING THROUGH VERY EARLY MORNING HOURS OF MONDAY. LOW TEMPS TONIGHT /UNDER PLENTY OF LINGERING AND MORE SHALLOW...WARMER LOWER CLOUDS/ WILL RANGE FROM NEAR 20 DEG IN THE NORTH TO 30F IN ACROSS THE SOUTH. BLUSTERY AND COLDER CONDITIONS WILL MAKE A RETURN ON MONDAY AS SYSTEM NUMBER ONE SLIDES OFF TO OUR EAST. OTHER THAN THE USUAL POST FRONTAL SNOWS SHOWERS...FAVORING WESTERN HIGHER ELEVATIONS...CONDITIONS WILL BE GRADUALLY IMPROVING OVERALL THROUGHOUT THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE AND ITS FAIR WEATHER AND LIGHT WIND WILL BE SHORT LIVED MONDAY NIGHT INTO TUESDAY WHEN THE NEXT IN THE SERIES OF STORM SYSTEMS IS SLATED TO ENTER THE LOCAL WEATHER SCENE. THIS ONE PROMISES MORE OF A MESSY OUTCOME AS IT SHOULD TRACK WELL TO OUR NW...MEANING WARM AIR EVENTUALLY INVADING THE REGION...WITH A SNOW TO SLEET/FREEZING RAIN AND EVEN RAIN SCENARIO. SNOW AMOUNTS DO NOT LOOK TO BE THE BIGGEST PART OF THE MIDWEEK STORM AS WE ARE PROGGED TO WARM ALOFT RATHER QUICKLY. WITH A DEEP SNOW PACK AND A LOT OF COLD AIR TO DISPLACE...WE WILL LIKELY SEE A PERIOD OF ICING BEFORE WARM AIR EVENTUALLY CHANGES EVERYTHING TO RAIN TUESDAY NIGHT INTO WEDNESDAY. RAIN SHOULD TAPER OFF TO SCATTERED SHOWERS WITH THE PASSAGE OF THE TRAILING COLD FRONT EARLY WEDNESDAY. EARLIER MODEL RUNS SUGGESTED LATER WEDNESDAY INTO THURSDAY THERE COULD BE A RETURN OF SNOW TO SRN PA ASSOCIATED WITH A FLAT SRN STREAM WAVE...BUT LATEST OPERATIONAL ECMWF/GFS NOW KEEP THE SURFACE WAVE SUPPRESSED MAINLY SOUTH OF THE REGION..HINTING THAT ONLY FAR SERN AREAS WILL BE AT RISK FOR A PERIOD OF OVER RUNNING SNOW. THE 06Z GEFS IS A LITTLE MORE GENEROUS WITH THE POPS SO IT`S NOT OUT OF THE QUESTION THAT SOMETHING WILL YET HAPPEN AS MODELS TRY AND RESOLVE SMALL SCALE FEATURES DROPPING OUT OF CENTRAL CANADA INTO THE EASTERN US LONG WAVE. TOO FAR OFF TO LEAN ONE WAY OR ANOTHER FOR A SOLUTION. BEHIND THE MID WEEK SYSTEM...ANOTHER PUSH OF ARCTIC AIR WILL BRING TEMPS AND POPS BACK WELL BELOW NORMAL FOR LATE THURSDAY INTO FRIDAY. THE ONLY GOOD THING SEEMS TO BE EACH ARCTIC SHOT IS A LITTLE LESS POTENT THAN THE LAST AS WE LEAVE THE RECORD COLD OF FEBRUARY BEHIND. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS ACROSS CENTRAL PA AT 06Z AS HIGH PRESSURE WHICH HAS PROVIDED VFR CONDITIONS ACROSS THE REGION DRIFTS EASTWARD. AS A WAVE OF LOW PRESSURE AND ASSOCIATED SNOW RAPIDLY APPROACH FROM THE WEST...EXPECT A CORRESPONDING RAPID DETERIORATION OF CONDITIONS FOR MOST OF THE REGION...BETWEEN 08Z AND 12Z. EXPECT FAR SOUTHEAST AIRFIELDS TO HOLD ON TO VFR CONDITIONS LONGEST...AND MAY MAKE IT THROUGH MID/LATE MORNING BEFORE THE SNOW AND RESTRICTIONS MOVE IN. GENERALLY IFR TO LIFR CONDITIONS IN SNOW EXPECTED ALL DAY SUNDAY AND SUNDAY NIGHT. STILL THE THREAT OF SOME FZRA MIXING IN IN THE SOUTHERN TIER COUNTIES LATER SUNDAY AND SUNDAY NIGHT. CONDITIONS SHOULD SLOWLY BEGIN TO IMPROVE ON MONDAY...BUT EXPECT RESTRICTIONS TO LINGER IN THE WESTERN AND NORTHERN HIGHER TERRAIN ON COLD NORTHWEST WINDS AND TYPICAL OROGRAPHIC SNOW SHOWERS. BRIEF RESPITE LATER MONDAY INTO EARLY TUESDAY...BEFORE THE NEXT SYSTEM PUSHES ANOTHER ROUND OF PRECIPITATION AND REDUCED FLYING CONDITIONS INTO THE AREA LATER TUESDAY AND WEDNESDAY. OUTLOOK... SUN...WIDESPREAD IFR WITH SNOW NORTH AND MIXED PRECIPITATION SOUTH. MON...CIG/VIS REDUCTIONS MAINLY AM...THEN IMPROVING CONDITIONS. TUE...VFR AM. MIXED PRECIP WITH CIG/VIS REDUCTIONS POSSIBLE LATE. WED...CIG/VIS REDUCTIONS CONTINUE IN WINTRY MIX/RAIN. THU...SLOWLY IMPROVING CONDITIONS...LINGERING MVFR NW AND SE. && .CLIMATE... THE BOOKS HAVE CLOSED AND WE NOW HAVE /AND MADE IT THROUGH/ THE COLDEST FEBRUARY ON RECORD. MONTHLY MEAN TEMPERATURES WERE...IPT 18.1...MDT 20.9. THE PREVIOUS RECORDS FOR THE COLDEST FEBRUARY...IPT 19.3...MDT 21.4 BOTH SET IN 1934. THIS FEBRUARY RANKED AS THE THIRD COLDEST CALENDAR MONTH EVER AT IPT...AND FOURTH COLDEST EVER AT MDT. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR PAZ019-027- 028-037-041-042-045-046-049>053-058. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR PAZ004>006- 010>012-017-018-024-033. WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR PAZ025-026-034>036. WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR PAZ056-057- 059-063>066. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT/DANGELO LONG TERM...LA CORTE AVIATION...JUNG/RXR CLIMATE...LAMBERT

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