Area Forecast Discussion
Issued by NWS State College, PA

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351
FXUS61 KCTP 091141
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
641 AM EST TUE FEB 9 2016

.SYNOPSIS...
A UPPER LOW WILL MOVE INTO THE REGION FROM THE OHIO VALLEY AND
TRANSITION INTO A LONG WAVE TROUGH. A WIDESPREAD LIGHT TO
MODERATE SNOW TODAY WILL TAPER OFF IN THE EVENING. LAKE EFFECT
AND UPSLOPE SNOW SHOWERS WILL FOLLOW FOR MID WEEK INTO THE FIRST
PART OF THE WEEKEND. ADDITIONAL ACCUMULATION ARE LIKELY IN THE
FAVORED NORTHWEST SNOWBELT AND HIGHER TERRAIN ALONG THE
ALLEGHENIES AND LAURELS. THE COLDEST AIRMASS OF THE WINTER IS
POISED TO BRING FRIGID TEMPERATURES AND DANGEROUS WIND CHILLS FOR
VALENTINES WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
630 AM UPDATE...
FINALLY SNOWING OUT THE WINDOW BUT NO ACCUM YET - EVEN ON THE
CARS. MCV-LIKE FEATURE EASY TO PICK OUT ON THE IR LOOP THIS
MORNING OVER WV. THIS FEATURE WILL SLIDE INTO THE STATE FROM THE
SW. THE FORCING AHEAD OF IT IS ALREADY BEGINNING TO CREATE A
COHERENT AREA OF LIGHT SNOW. RADAR RETURNS GRADUALLY INCREASING IN
THE LAST FEW FRAMES AND SPREADING NORTHWARD FROM WV/MD. WORST OF
THE VSBYS ARE KHGR AND KMDT - BUT THEY ARE >1SM AT THIS TIME. WILL
CONTINUE TO RIDE THE FCST AS IS...ALLOWING THE SNOW TO FALL FOR A
WHILE BEFORE TAKING ANY FURTHER ACTION.

PREV...
LOTS OF DECISIONS THIS MORNING WITH THE OVERWHELMING MESSAGE ONE
OF LOWER SNOWFALL NUMBERS. HAVE MADE ONE SMALL CHANGE TO THE
FLAGS BY ADDING SCHUYLKILL COUNTY INTO THE ADVY. REASONING IS THAT
THE TEMPERATURE PROFILE WILL FAVOR AN ELEVATION-DEPENDENT
SNOWFALL. THE TEMPS IN THE VALLEYS WILL BE MARGINAL FOR EFFICIENT
ACCUMULATIONS. HOWEVER...THE IN-CLOUD PROFILE AND TEMPS IN THE
HIGHER ELEVATIONS DO FAVOR SOME 15:1 RATIOS DURING THE DAYLIGHT
HOURS. SO...ARMED WITH THAT...HAVE DECIDED TO HOLD ONTO THE
WARNING AND REST OF THE ADVYS AS IS FOR THE TIME-BEING. HAVE TRIED
REALLY HARD TO KEEP ACCUMS IN THE WARNING RANGE - BUT HAVE
CONFINED THEM TO THE HIGHER ELEVATIONS. IT WILL LIKELY WORK OUT
THAT THE HILLTOPS IN THE WARNING-AREA COULD GET 5-7 INCHES WHILE
THE CITIES AND LOWEST ELEVATIONS GET ONLY AN INCH OR TWO. THE
DISORGANIZED LOOK TO THE FORCING WILL PROBABLY MEAN NO LONG-LIVED
BANDING AND ONLY LIMITED TIMES OF 1 IN/HR RATES IF ANY AT ALL. QPF
AMOUNTS LOOKING PRETTY TENUOUS AS WELL WITHOUT ANOMALOUS PWATS AND
NO GOOD OFF-OCEAN/GULF FLOW TO TAP INTO ADDITIONAL HELP. WITH THE
EXPECTED MELTING...WE ARE IN DANGER OF NOT MAKING WARNING NUMS -
CERTAINLY IF WE TAKE INTO ACCOUNT THE 12-HR CRITERIA. SO MANY
THINGS GOING AGAINST WARNING SNOW ACCUMS...BUT THE CAT IS OUT AND
RUNNING AROUND ALREADY. SINCE WE ALREADY HAVE THE WARNING
UP...HAVE CHOSEN TO GIVE IT A LITTLE MORE TIME FOR THE STORM TO
SHOW IT/S HAND. RATHER NOT TAKE DOWN THE WARNING BEFORE IT EVEN
HAS A CHANCE TO GET INTO THE PROGGED HEAVIEST PRECIPITATION.

TIMING LOOKS LIKE THE SRN TIER WILL GET SOME STEADY SNOW THIS
MORNING BUT THEN THE BEST FORCING SEEMS LIKE IT WILL BE OVER THE
LAURELS THIS AFTERNOON AND SLIDE ACROSS THE CENTRAL MOUNTAINS AND
OFF TO THE EAST THIS EVENING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
UPPER LOW WILL BE FILLING AND LOSING IT/S CLOSED
CONTOURS...BECOMING A LONG WAVE TROUGH TONIGHT. SNOW WILL PROBABLY
BE SLIDING STEADILY TO THE EAST IN THE EVENING AND BE OFF TO THE
EAST OF CENTRAL PA BY MIDNIGHT. THE HEIGHTS STILL LOWER
SOME...THOUGH...AND SOME 1/2 TO 1 IN/HR RATES ARE POSSIBLE ALONG
WHAT MAY TURN OUT TO BE A FRONTAL BAND AS THE BEST COLD AIR MOVES
IN AT LOW LEVELS AND WINDS PICK UP FROM THE WEST.

THINGS THEN TRANSITION TO A PLAIN-OL UPSLOPE SNOW SITUATION FOR
THE LAURELS. A LM CONNECTION DEVELOPS UNDER HIGHLY-FAVORABLE
TEMPERATURES/CONDITIONS. THE AIR DOES DRY OUT ON THE WHOLE...SO
MOST OTHER LOCATIONS WILL SEE LITTLE MORE THAN FLURRIES. DOWNSLOPE
MAY ALLOW THE SE TO GET A DEG OR TWO WARMER THAN TODAY. THE LAKE
EFFECT IN THE NW WILL BE RAMPING UP...BUT THE STACKED WEST WIND
PROFILE FAVORS WRN NY STATE THAN NW PA. OF COURSE...THE COLD AIR
WILL LIKELY EXTEND SOME BANDS INTO WARREN CO. HAVE CHOSEN TO HOLD
OFF ON ANY LK EFF FLAGS FOR NOW - SINCE THE NEED FOR A
WATCH/WARNING IS NOT QUITE 50PCT AND TIMING IS SUCH THAT THE
CURRENT WIDESPREAD SNOW AND WARNS/ADVYS ELSEWHERE MAY BE
CONFUSING. IT WILL BE COMPLICATED ENOUGH FOR THE LAURELS WHERE THE
SNOW WILL NEVER REALLY TAKE A BREAK.

TEMPS DROP OFF QUITE QUICKLY LATE WED. MINS MAY GET INTO THE
SINGLE DIGITS ON THE HILL TOPS OF THE ALLEGHENIES AND LAURELS.
WIND CHILLS WILL GO BELOW ZERO.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
*IMPACT WEATHER HIGHLIGHTS INCLUDE ADDITIONAL LAKE EFFECT AND
 UPSLOPE SNOW ACCUMULATIONS THURSDAY-SATURDAY...FOLLOWED BY FRIGID
 TEMPERATURES AND DANGEROUSLY COLD WIND CHILLS FOR VALENTINES
 WEEKEND.

ANOMALOUS WESTERN RIDGE/EASTERN TROUGH PATTERN WILL REMAIN IN
PLACE THROUGH THE WEEKEND. THE GLOBAL ENSEMBLE MEANS GENERALLY
KEEP THIS PATTERN CONFIGURATION INTACT INTO NEXT WEEK BUT AT A
DECREASING AMPLITUDE.

AS THE BROAD UPPER LEVEL CIRCULATION DEPARTS OVER THE NORTHEAST
TOWARD THE END OF THE WEEK...IT WILL BE REPLACED BY A POLAR
VORTEX DROPPING SOUTH ACROSS HUDSON BAY INTO SE CANADA. COLD AIR
WILL BEGIN SPILLING SOUTHWARD LATER IN THE WEEK...REINFORCED
INITIALLY BY A SECONDARY FRONT ON THURSDAY. CONFIDENCE CONTINUES
TO INCREASE IN A SIGNIFICANT ARCTIC AIR INTRUSION/COLD OUTBREAK
FOR VALENTINE`S WEEKEND.

LAKE EFFECT/UPSLOPE SNOWS FOR SEVERAL DAYS THU-SAT WILL BRING
ADDITIONAL LGT-MDT ACCUMULATION OVER THE FAVORED NORTHWEST
SNOWBELT DOWNWIND OF LAKE ERIE AND IN THE HIGHER TERRAIN OF THE
ALLEGHENIES/LAURELS. A NEW ELEMENT IN THE FCST IS DEVELOPING LOW
PRESSURE OFF THE MID-ATLANTIC/NORTHEAST COAST BY EARLY SATURDAY.
AT THIS TIME THE 08/00Z ECMWF LIES ON THE WESTERN EDGE OF THE
GUIDANCE ENVELOPE.

CONFIDENCE IS HIGH IN THE FCST COLD PATTERN/WELL-BELOW NORMAL
TEMPERATURES THROUGH THE PERIOD. THE COLDEST AIRMASS OF THE
WINTER APPEARS POISED TO ARRIVE THIS WEEKEND WITH GFS/EC BOTH
BRINGING -30C AIR AT 850MB INTO PA.

MAX/MIN TEMPERATURE DEPARTURES OF -20 TO -25 DEGREES BELOW CLIMO
ARE PROBABLE SATURDAY AND SUNDAY. WIDESPREAD SINGLE DIGIT
TEMPERATURES +/- ZERO ARE FCST SATURDAY NIGHT INTO EARLY SUNDAY.
A STRONG GRADIENT BETWEEN LOW PRESSURE OFF THE NEW ENGLAND COAST
AND 1040+MB ARCTIC HIGH DROPPING INTO THE UPPER MS VALLEY WILL
PRODUCE GUSTY WINDS AND DANGEROUSLY COLD WIND CHILLS -10F TO -25F
DEGREES BELOW ZERO.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
12Z TAFS SENT.

EXPECT A WIDE RANGE OF CONDITIONS TODAY...AS A COMPLEX AREA OF
LOW PRESSURE REMAINS OVER THE AREA.

SNOW HAS BEEN PATCHY SO FAR...BUT EXPECT THE SNOW TO BECOME
MORE WIDESPREAD THIS MORNING...AS AN AREA OF COLDER CLOUD TOPS
OVER WV EXPANDS NORTHWARD INTO CENTRAL PA.

EXPECT CONDITIONS TO IMPROVE EAST OF THE MOUNTAINS BY WED
MORNING...AS WINDS SHIFT MORE TO THE WEST AND NW.

POOR CONDITIONS WILL OCCUR AT TIMES FROM WED INTO THE FIRST
PART OF THE WEEKEND...WITH SNOW SHOWERS...AND GUSTY WINDS
AT SPOTS LIKE JST AND BFD.

OUTLOOK...

WED...MAINLY IFR IN SNOW WRN AIRSPACE. MVFR-VFR CIGS
CENTRAL/EAST.
THU-SAT...MVFR IN -SHSN W MTNS. VFR ELSEWHERE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR
PAZ025>028-034>036-056>059-063.
WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR PAZ024-
033.
WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR PAZ064>066.

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...STEINBUGL
AVIATION...MARTIN



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