Area Forecast Discussion
Issued by NWS State College, PA

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000
FXUS61 KCTP 282353
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
653 PM EST SAT FEB 28 2015

.SYNOPSIS...
HIGH PRESSURE OVER PENNSYLVANIA WILL PASS OFF THE NEW ENGLAND
COAST THIS EVENING. LOW PRESSURE TRACKING UP THE OHIO VALLEY
SUNDAY WILL CROSS PENNSYLVANIA SATURDAY NIGHT...BRINGING SNOW AND
MIXED PRECIPITATION TO CENTRAL PA THROUGH EARLY MONDAY MORNING.
A STRONGER AREA OF LOW PRESSURE WILL LIKELY TRACK WEST OF
PENNSYLVANIA LATE TUESDAY AND EARLY WEDNESDAY.

&&

.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
HIGH CLOUDS SHOULD THICKEN UP QUICKLY TONIGHT AS MOISTURE STREAM
EWRD ON FAST/ZONAL FLOW. HIGH PRESSURE STILL ALLOWING TEMPS TO
DROP DUE TO LIGHT WINDS. BUT...WITH THE MOISTURE THICKENING UP A
LITTLE QUICKER THAN ANTICIPATED...IT MAY HOLD TEMPS UP A FEW DEGS
AND THEY SHOULD PRACTICALLY HALT EARLY TONIGHT. EXPECT THAT THE
FASTER ONSET WILL BRING THE FIRST WAVE OF WARM ADVECTION SNOW
INTO THE NW BY 09Z AND ACROSS ABOUT THE NWRN 3/4S OF THE AREA BY
13Z. BUT IT SHOULD BE ONLY BRIEFLY HEAVY. MAIN CHANGES ARE TO
SHORT TERM.

&&

.SHORT TERM /MIDNIGHT TONIGHT THROUGH SUNDAY NIGHT/...
630 PM UPDATE...
18Z NAM GFS AND MOST SREF MEMBERS FROM 15Z NOW AGREE UPON A
SCENARIO NOT UNLIKE/VERY SIMILAR TO LAST WEEKEND/S STORM WHERE THE
PRECIP MAY BE A LOT LIGHTER IN THE CENTRAL MTNS AND HEAVIER IN THE
SERN THIRD OF THE AREA...AS COLD AIR HANGS ON MUCH LONGER THRU THE
TIME WHEN IT IS PRECIPPING. THE TEMPS DO NOT WARM ABOVE FREEZING
IN THE SRN TIER UNTIL VERY CLOSE TO THE END OF THE ACCUM PRECIP.
DRY SLOT SEEMS TO HIT THE SC MTNS IN THE EARLY AFTN AND THEN SLIDE
EAST AND END PRECIP BY 00Z MON IN THE SERN COS. THEREFORE WILL
DOWNPLAY THE ZR AND GO WITH MORE SNOW AND SLIGHTLY HIGHER QPF IN
THE AFTN FOR THE SERN COS. THIS MAKES A BIG CHANGE /UPWARD/ IN THE
SNOW NUMBERS FOR THE LOWER SUSQ AND A SLIGHT DOWN- TICK FOR MUCH
OF THE OTHER PARTS OF THE REGION EXCEPT THE WRN MTNS. ALL ARE
STILL IN ADVY- LEVEL NUMBERS...BUT MORE FROZEN PRECIP IS EXPECTED
NOW. WILL NOT ADJUST THE FLAGS...BUT RE- WORD THE WSW SLIGHTLY.

PREV...
UPCOMING PRECIP WILL EXTEND BETWEEN A 12-24 HOUR EVENT... MEANING
THAT 24 HOUR WATCH/WARNING CRITERIA MUST BE USED TO VERIFY
AMOUNTS. HERE IN CENTRAL PA...THAT MEANS A MID POINT OF 8" MUST
ACCUMULATE IN 24 HOURS FOR WARNING CRITERIA TO BE MET...AND THE
OVERWHELMING CONSENSUS AFTER LOOKING AT MORNING DATA SUITE IS THAT
WE WON`T SEE THAT EXCEPT FOR SPOT AMOUNTS ACROSS THE NORTHWEST OR
WEST CENTRAL MOUNTAINS WHERE WATCHES WERE IN EFFECT.

COLLAB WITH ALL SURROUNDING OFFICES HAS PROMPTED ADVISORY
ISSUANCES FOR ALL OF MY COUNTIES. ACROSS THE NORTHWEST...A GENERAL
6 TO 8 INCHES IS EXPECTED...WHILE ELSEWHERE 2 TO 4 INCHES AND A
COATING OF ICE WILL BE COMMON. FOR THE FAR SOUTH AND SOUTHEAST...
A COATING TO LESS THAN TWO INCHES OF SNOW IS EXPECTED TO BE
FOLLOWED BY ONE TO TWO TENTHS OF AN INCH OF FREEZING RAIN. LITTLE
IN THE WAY OF WIND MEANS THIS SHOULD NOT BE A PARTICULARLY
DAMAGING OR DISRUPTIVE EVENT (IN TERMS OF POWER, ETC).

BLEND OF MORNING MDL OUTPUT BRINGS LIGHT SNOW INTO THE WEST
CENTRAL MOUNTAINS BEFORE DAWN SUNDAY. FOR THE REST OF CENTRAL
PA...LGT SNOW IS LIKELY TO ARRIVE BY LATE AM.

AGREE WITH PREVIOUS THINKING THAT HEAVIEST PRECIP WILL LIKELY
HOLD OFF UNTIL STRONGER FORCING ARRIVES WITH APPROACH OF N STREAM
SHORTWAVE DIVING ACROSS THE GRT LKS SUNDAY PM. ASSOC LL JET AND
SURGE OF WARMER AIR ALOFT WILL LKLY CHANGE LGT SNOW TO A WINTRY
MIX ACROSS SOUTHERN PA LATE SUNDAY AND SUNDAY EVENING...WHILE MDL
SOUNDINGS AND ENSEMBLE PTYPE PLUMES INDICATE ALL SNOW ACROSS AREAS
NORTH OF I-80.

THE TRANSITION TO FREEZING RAIN SHOULD TAKE PLACE FROM LATE
AFTERNOON THROUGH LATE EVENING SUNDAY ACROSS THE SOUTHERN HALF OF
MY CWA. PRECIP LOOKS TO TAPER OFF IN ALL AREAS DURING THE PRE DAWN
HOURS MONDAY MORNING.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
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 IMPROVING OVERALL.

HIGH PRESSURE 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 /00Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE WHICH HAS PROVIDED VFR CONDITIONS ACROSS THE REGION
WILL DRIFT EAST TONIGHT...WITH MID CLOUDS INVADING FROM THE WEST
BETWEEN 03Z AND 05Z.

AS A WAVE OF LOW PRESSURE AND ASSOCIATED SNOW RAPIDLY APPROACH
FROM THE WEST...EXPECT A CORRESPONDING RAPID DETERRIORATION 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 COLDEST FEBRUARY ON RECORD IS STILL LOOKING LIKELY.

MONTHLY MEAN TEMPERATURES THROUGH THE 27TH...IPT 18.2...MDT 20.9.

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...
WINTER WEATHER ADVISORY FROM 7 AM SUNDAY TO 7 AM EST MONDAY
FOR PAZ006-012-018-019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.
WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 7 AM EST MONDAY
FOR PAZ004-005-010-011-017.

&&

$$
SYNOPSIS...DANGELO/DEVOIR
NEAR TERM...DANGELO/DEVOIR
SHORT TERM...DANGELO/DEVOIR
LONG TERM...LA CORTE
AVIATION...JUNG
CLIMATE...LA CORTE



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