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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBGM 010701
AFDBGM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
201 AM EST SUN FEB 1 2015

.SYNOPSIS...
AN APPROACHING WINTER STORM WILL BEGIN TO IMPACT THE AREA BY LATE
TODAY, WITH ACCUMULATING SNOW CONTINUING INTO MONDAY. BITTERLY
COLD TEMPERATURES WILL FOLLOW AGAIN MONDAY NIGHT AND TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1010 PM UPDATE...
TEMPS ARE FALLING MUCH MORE RAPIDLY THAN PREVIOUSLY THOUGHT UNDER
CLR SKIES AND SNOW CVR. HV UPDATED GRIDS TO ACCOUNT FOR THIS WITH
A VRY GRADUAL RISE EXPECTED THRU THE REST OF THE OVRNGT AS OVC IS
SPREADING INTO RMNDR OF AREA BY 06Z. EXPECT TEMPS WL CONTINUE TO
BOTTOM OUT ACRS THE ERN ZONES FOR A TIME TONIGHT UNTIL WARM
ADVECTION KICKS IN. NO OTHER CHGS NEEDED AT THIS TIME.

PREV DISCUSSIONS BLO...

815 PM UPDATE...
SFC LOW AND ASSOCIATED TROF IS SITTING OVR SRN ONTARIO IN VICINITY
OF GEORGIAN BAY AS OF 01Z. THIS IS DROPPING SOUTH TWD CWA WITH VRY
LGT SNOW/FLURRIES AHD OF IT. SLGT WRM ADVECTION OCCURRING ACRS WRN
NY AND WRN PORTIONS OF CWA PRESENTLY AS FLOW TURNS MORE SWRLY.
EXPECT TEMPS WL SLOWLY RISE TONIGHT AND CURRENT GRIDS HV THIS WELL
IN HAND.

CANNOT RULE OUT A FLURRY OR TWO ACRS NRN ZONES THRU MIDNIGHT BUT
TROF WL LKLY RESULT IN SCTD SNOW SHOWERS CLOSER TO 06Z AND HV
DROPPED POPS SLIGHTLY. TROF WL EVENTUALLY STALL OUT AND WITH WINDS
TURNING MORE SRLY DRG THE AFTN EXPECT OVERRUNNING TO BEGIN. HV
DROPPED POPS THRU 12Z AS UPGLIDE DOES NOT LOOK TO BEGIN IN ERNEST
UNTIL AFT 18Z. NO OTHER CHGS NEEDED TO GRIDS WITH THIS UPDATE AND
AWAITING 00Z RUNS IN REGARD TO WINTER STORM.

130 PM UPDATE...
WARM AIR ADVECTION, OR WHAT THERE IS OF IT AT LEAST, WILL BEGIN A
FEW HOURS AFTER SUNSET AHEAD OF APPROACHING CYCLONE. FOR THIS
REASON WE ARE RUNNING A NON-DIURNAL TEMPERATURE TREND.
TEMPERATURES MAY BOTTOM OUT BEFORE 3Z AND THEN SLOWLY RISE
THROUGH THE OVERNIGHT HOURS, AS CLOUDS THICKEN.

WEAK TROF DIPPING ACROSS THE FA OVERNIGHT WILL CAUSE FLURRIES AND
LIGHT SNOW SHOWERS FROM MIDNIGHT THROUGH SUNRISE, SPREADING FROM
NORTH TO SOUTH.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
345 PM UPDATE... THE BIG STORY, OF COURSE, IS THE UPCOMING WINTER
STORM. MOST OF THE FOLLOWING DISCUSSION WILL FOCUS ON THIS ASPECT.

ONLY SPORADIC -SHSN/FLRYS ARE FORESEEN EARLY SUNDAY, AS THE WEAK
LOW-LVL TROUGH MENTIONED IN THE PREV SXN DROPS SWD INTO PA.

CURRENT MODEL TIMING WOULD SUGGEST THAT THE LEADING EDGE OF THE
STEADIER LGT SNOW OVERSPREADS THE CNTRL SRN TIER/WRN FINGER
LAKES/NE PA ZNS FROM ABT 18-21Z, THEN MUCH OF THE REMAINDER OF CNY
21-00Z, AND OUR FAR NERN ZNS 00-03Z SUN EVE. WE DECIDED TO KEEP IT
SIMPLE AND JUST INDICATE A MORE GENERIC 21Z SUN START TIME FOR OUR
WATCH/WARNING CONFIGURATION. FOR THE FIRST FEW HRS AFTER THE SNOW
INITIALLY STARTS, THE INTENSITY SHOULD BE FAIRLY LIGHT, AS THE
COLUMN GRADUALLY SATURATES.

THE HEART OF THE STORM SHOULD OCCUR OVERNIGHT SUN INTO MON, WHEN
FORCED LIFT MAXIMIZES, OWING TO STG THERMAL ADVECTION
FORCING, GOOD UPR-LVL JET SUPPORT, AND FAVORABLE CRYSTAL GROWTH
MECHANICS. ALTHOUGH MODEL CONSENSUS IS FAIRLY TIGHT OVERALL WITH
THE SYSTEM ATTM, A SUBTLE NWD JOG TO THE OVERALL STORM TRACK AND
ASSOCD WARM AIR SURGE ALOFT WAS AGN NOTED. THIS IS WELL REFLECTED
IN THE LAST COUPLE OF SREF RUNS (09/15Z SUN), WHICH INDICATE THE
POTENTIAL FOR SLEET/FRZG RAIN IN OUR FAR SRN ZNS EARLY MON. IT`S
INTERESTING TO NOTE THAT THE 12Z GFS WAS THE WARMEST
MODEL, SHOWING THAT KAVP MAY EVEN HAVE A PD OF PLAIN RAIN MON
MRNG. FOR NOW, SINCE THIS WAS A WARM OUTLIER, WE WENT MORE WITH A
MIDDLE OF THE ROAD SREF SCENARIO. AS A RESULT, WE INDICATE A
WINTRY MIX PD (SN/PE/FZRA) FROM ABT 09-15Z MON OVER OUR FAR SRN
ZNS (MAINLY ALG AND S OF I-84). THIS IS OUR RGN OF HIGHEST
UNCERTAINTY, AS A LONGER STRETCH OF MIXED PHASE COULD CONCEIVABLY
CUT DOWN ON OUR PRESENT SNOW TOTAL FCST (8-12"), PARTICULARLY FOR
THE WYO/LACK VLYS.

FARTHER N, CONFIDENCE IS HIGHER IN AN ALL SNOW SCENARIO, WITH
6-10" FORESEEN FROM ABT KPEO-KSYR-KRME, AND 8-12", WITH LOCALIZED
AREAS NEAR 14", ACRS THE TWIN TIERS. IT IS SOMEWHERE OVER THE TWIN
TIERS WHERE THE BEST COMBINATION OF STG WAA FORCING ON THE FRONT
SIDE OF THE STORM, AND DEFORMATION/FGEN BANDING POTENTIAL ON THE
BACK SIDE OF THE STORM, SEEMS TO EXIST. IN NRN ONEIDA, CONFIDENCE
IN SNOW TOTALS OF 7+" HAS INCREASED ENUF TO GO WITH A WINTER STM
WATCH. WE SHOULD BE ABLE TO PIN THIS AREA DOWN MORE (WRNG VS.
ADVSY) LTR TNT/EARLY SUN.

STG CAA IS ALSO ANTICIPATED ON THE BACK END OF THE STORM STARTING
MON AFTN. THUS, FALLING TEMPS ARE EXPECTED BY/AFTER 18Z, WITH
READINGS DOWN TO THE SINGLE DIGITS IN MANY AREAS BY LTR IN THE
DAY. TIGHTENING PRES GRADIENT MON AFTN-MON NGT SHOULD ALSO CREATE
INCREASINGLY GUSTY WINDS/LWRG WIND CHILLS. WIND CHILL FLAGS MAY BE
NEEDED BY THEN, AND THIS NEXT ARCTIC SURGE WAS NOTED ONCE AGN IN
THE HWO.

ALTHOUGH SOME LES IS ANTICIPATED MON NGT, THE INTENSITY/DURATION
MAY WELL BE LIMITED BY DECREASING MOISTURE SUPPLY, AND THE
APPROACH OF SFC RIDGING BY TUE MRNG. TUE LOOKS MAINLY DRY AND
COLD.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
130 AM UPDATE...
LITTLE CHANGE. REMAIN COLD IN AN EAST COAST TROF. FOLLOWED LATEST
WPC GUIDANCE. DISCUSSION BELOW STILL VALID. LATE SAT INTO MONDAY A
SLOW MOVING TROF MOVES THROUGH WITH LIGHT SNOW. SOME TEMPERATURE
MODERATION AFTER FRIDAY MORNINGS BELOW ZERO LOWS.

PREVIOUS DISCUSSION FROM SAT AFTN...
VERY COLD UPPER LEVEL TROF WILL REMAIN FIXED OVER THE EASTERN
UNITED STATES THROUGH THE EXTENDED PERIOD. A TROF MOVING OUT OF
THE GREAT LAKES WILL STRENGTHEN OVER LAKE ONTARIO ON WEDNESDAY,
SPREADING AN INCH OR TWO OF SNOW ACROSS NY AND PA THROUGH THURSDAY
MORNING.

THE REMAINDER OF THE PERIOD LOOKS DRY AND RATHER COLD. BESIDES
THE NEAR-NORMAL TEMPERATURES FORECAST FOR WEDNESDAY, MOST OF THE
MAXIMUM TEMPERATURES WILL BE 10 TO 20 DEGREES BELOW NORMAL. THE
COLDEST DAY APPEARS TO BE THURSDAY BEHIND THE MID-WEEK CYCLONE.
925MB TEMPS ARE IN THE -17C T0 -20C RANGE ACCORDING TO THE ECMWF.
THIS AIRMASS WILL YIELD MAXIMUMS IN THE SINGLE DIGITS TO LOW
TEENS. FRIDAY MORNING LOOKS FRIGID, WITH WIDESPREAD -5F TO -15F
TEMPERATURES FORECAST. THE RURAL VALLEYS WILL BE EVEN COLDER.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
1230 AM UPDATE...

A WEAK FRONT FROM THE NW WILL BRING MVFR CLOUDS AND FLURRIES EARLY
THIS MORNING NY TERMINALS. MVFR CIGS NOW AT ITH SYR AND BY 9Z
REST OF NY. AT KAVP REMAINING VFR.

LATE MORNING INTO AFTN SYR AND RME WILL IMPROVE TO VFR BUT REST OF
NY WILL REMAIN MVFR DUE TO CIGS.

A STRONGER STORM WILL APPROACH NY/PA EARLY AFTERNOON. THE STORM
WILL BRING 1 TO 2 SM VISIBILITIES TO AVP, BGM, ITH, AND ELM
BETWEEN 17Z AND 21Z. BY 03Z VSBYS 1SM OR LESS AND CIGS POSSIBLY
IFR. AT SYR AND RME LATER BETWEEN 00 AND 02Z.

LIGHT AND VARIABLE WINDS BECOMING NORTH AT 4 TO 8 KTS LATE MORNING
THEN NE TO E SUN EVE.

OUTLOOK...

SUN NGT/MON...IFR RESTRICTIONS IN SNOW.

MON NGT...IMPROVEMENT TO VFR FROM S TO N.

TUE/TUE EVE...VFR.

TUE OVERNIGHT/WED/THU...POSSIBLE RESTRICTIONS DUE TO SNOW
SHOWERS.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     MONDAY FOR PAZ038>040-043-044-047-048-072.
NY...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM EST
     MONDAY FOR NYZ015>018-022>025-036-037-044>046-055>057-062.
     WINTER STORM WATCH FROM THIS AFTERNOON THROUGH MONDAY
     AFTERNOON FOR NYZ009.

&&

$$
SYNOPSIS...DJP/MLJ
NEAR TERM...DJP/PVF
SHORT TERM...MLJ
LONG TERM...DJP/TAC
AVIATION...TAC