662 
FXUS61 KBGM 181811
AFDBGM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
211 PM EDT MON MAR 18 2013

.SYNOPSIS...
A LARGE COMPLEX STORM SYSTEM WILL SPREAD ACCUMULATING SNOW,
SOUTHWEST TO NORTHEAST ACROSS THE REGION THIS AFTERNOON AND
EVENING. TONIGHT INTO TUESDAY MORNING, THE SNOW WILL BECOME MIXED
WITH RAIN, FREEZING RAIN, AND SLEET IN NORTHEAST
PENNSYLVANIA, AND SOME PORTIONS OF THE CATSKILLS AND CENTRAL NEW
YORK. WITH LOW PRESSURE BECOMING STUCK OVER OUR REGION, A COLD
UNSETTLED PATTERN WITH SCATTERED SNOW SHOWERS AND FLURRIES CAN BE
EXPECTED THROUGH THE REMAINDER OF THE WORKWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE...
MINOR CHANGES. SLOW DOWN ONSET TIME OF SNOW BY AN HOUR OR TWO.
TIMES IN BRIEFING AND AVIATION FORECASTS LOOK CLOSER. HIGH CLOUDS
OVER THE ENTIRE AREA ALREADY BUT LOWER CLOUDS WILL BE RIGHT WITH
SNOW. 

5 AM MON UPDATE... HIGH CLDNS CONTS TO SPREAD ACRS THE RGN EARLY
THIS MRNG...WITH A GRDL LWRG AND THICKENING OF THE CLOUD DECK
ANTICIPATED THROUGH MIDDAY. 

AS OF ABT 09Z...THE LEADING EDGE OF THE STEADIER PCPN EXTENDED
FROM CNTRL OH ACRS THE SRN TIER CNTYS OF PA. THIS LEADING EDGE
WILL CONTINUE TO MARCH NEWD THROUGH THE DAY...LIKELY REACHING OUR
FAR SWRN CNTYS ARND 15Z...THEN MUCH OF NE PA...NY'S SRN TIER...AND
THE FINGER LKS RGN BY 18-19Z...AND ULTIMATELY THE WRN MOHAWK
VLY/SRN TUG HILL RGN BY 21-22Z.

THIS INITIAL SHOT OF PCPN SHOULD EASILY TAKE THE FORM OF SNOW ACRS
CNY/NE PA...GIVEN THE RESIDENT COLD DRY AMS. STG FORCED ASCENT
FROM INCOMING OH VLY S/WV...AND GOOD 925-850 MB WAA/SPEED
CONVERGENCE...SHOULD LEAD TO A DECENT 3-6 HR PD OF SN/+SN...LASTING
INTO THE EVE HRS. WE'RE ANTICIPATING ADVSY-LVL ACCUMS (MAINLY IN THE
3-6" RANGE) FOR A GOOD MAJORITY OF THE CWA.

THE EC/GFS/NAM SOLNS HAVE NOW CONVERGED FOR THE OVERNIGHT
PD...INDICATING THAT AN ELEVATED WARM LYR (850-800 MB) WILL PUSH
THROUGH NE PA...AND INTO PTNS OF CNY...WHILE A DRY SLOT ALOFT ALSO
TEMPORARILY ROTATES IN FROM THE SW. THE UPSHOT OF ALL THIS IS THAT
PCPN WILL HAVE A TENDENCY TO TAPER OFF IN INTENSITY (SPCLY ACRS
OUR WRN ZNS) BY 03-06Z...WITH A MIXED BAG OF LGT SLEET/FZRA/RAIN
ALSO LIKELY EVOLVING FOR A GOOD PTN OF THE FCST AREA. IT'S
QUESTIONABLE WHETHER THE WARM LYR MAKES IT ALL THE WAY TO OUR FAR
NRN/NERN ZNS...AND THESE AREAS MAY STAY AS LGT SNOW. 

BY EARLY TUE (09-12Z)...DEEPER MOISTURE AND BETTER LIFT IS PROGGED
TO DEVELOP ONCE AGN FOR THE ERN HALF OF THE FA...AS A NEW SFC WV
DEEPENS AT THE TRIPLE PT OCCLUSION...NEAR OR JUST OFF THE DELMARVA
COAST. PRIND ARE THAT PTYP WILL HAVE A TENDENCY TO GO BACK TO SNOW
TUE AM...AS TEMPS ALOFT COOL...SPCLY FOR FAR ERN SXNS
(OTSEGO/DELAWARE/SULLIVAN)...WHERE SOME HVYR PCPN BANDS ARE LIKELY
UNDERNEATH IMPROVING MID-LVL FGEN FORCING. THE COMBINATION OF THE
HVYR SNOW BURST LATE MON AFTN/EVE...PLUS THE POTENTIAL FOR ADDTNL
ACCUMS TUE AM...HAS LED US TO UPGRADE OTSEGO/DELAWARE/SULLIVAN
CNTYS TO A WINTER STM WARNING (GENERALLY 5-10" TOTALS).

BY MID TO LATE TUE AFTN...THINGS SHOULD BE WINDING DOWN...AS THE
BETTER LIFT/MORE CONCENTRATED PCPN SHIFTS WELL TO OUR E INTO NEW
ENG. STG LOW-LVL CAA...ALG WITH INCREASINGLY MOIST CYCLONIC FLOW
FROM THE W...SHOULD LEAD TO SCTD SHSN/FLRYS FOR MUCH OF CNY AND
PA'S NRN TIER BY LATE IN THE DAY. GIVEN AN INITIAL 270 FLOW...WE
COULD BEGIN TO SEE A RESPONSE OFF LK ONT INTO THE SRN TUG HILL RGN
BY DAY'S END...ALG WITH SOME RENEGADE SHSN FROM LK ERIE PERHAPS
REACHING OUR WRN ZNS.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
420 AM UPDATE...
CONTINUED COLD AIR ADVECTION TUESDAY NIGHT...THEN 510-515
DECAMETER 1000-500MB THICKNESSES KEEP RESIDENCE THROUGH THE SHORT
TERM PERIOD...QUITE LOW FOR THIS TIME OF YEAR. WOBBLY DOUBLE-
CENTERED UPPER LOW WILL CONSOLIDATE INTO A SINGLE LARGE UPPER LOW
THAT WILL STUBBORNLY SIT OVER THE ONTARIO/QUEBEC/UPSTATE NY
REGION. MOIST CYCLONIC FLOW AROUND THE UPPER LOW...ALONG WITH
VORTICITY LOBES ROTATING AROUND IT...WILL ENSURE UNSETTLED PATTERN
WITH STEEP LOW LEVEL LAPSE RATES AND DIURNAL BLOSSOMS OF SCATTERED
SNOW SHOWERS AND GOOD AMOUNT OF CLOUD COVER. ALSO...RATHER GUSTY
WINDS DURING THE DAY WEDNESDAY...FREQUENTLY 25-35 MPH.

AIR MASS COLD ENOUGH FOR LAKE EFFECT TO ALSO BE A
PLAYER...PARTICULARLY NORTH OF THE NY THRUWAY TUESDAY NIGHT INTO
WEDNESDAY. ADVISORY LEVEL SNOW LOOKS QUITE POSSIBLE TOWARDS
NORTHERN ONEIDA COUNTY...WITH PERIODIC LIGHT COATINGS OF INCH OR
LESS ELSEWHERE THAT WILL BE VULNERABLE TO QUICK SUBLIMATION DURING
DAYTIME PERIODS COURTESY OF INCREASING NEAR-EQUINOX SUN
ANGLE...AND LOW DEW POINTS PLUS GUSTY WINDS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
2 PM UPDATE...
PLAN ON FOLLOWING WPC GUIDANCE FOR LONG TERM. UPPER LEVEL BLOCKING
REMAINS OVER GREENLAND LEADING TO UL LOW SPINNING ACRS NERN U.S.
THRU EARLY IN THE WEEKEND. THIS WL KEEP LOCHC POPS IN FOR SNOW
SHOWERS OR FLURRIES AND CLDY CONDS THRU SATURDAY. VRY LITTLE IN
THE WAY OF POPS EXPECTED SUNDAY AS MAIN STORM TRACK RMNS WELL TO
THE SOUTH PER 12Z GUIDANCE. TEMPS WL AVG BLO NORMAL THRU THIS
TIME.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
18Z UPDATE...
CONDITIONS WILL DETERIORATE BETWEEN 18Z AND 20Z AS SNOW MOVES IN
FROM THE SOUTHWEST. EXPECT IFR IN SNOW TO SET IN AT KELM BY 1830Z
AND MOVING NORTH AND EAST FROM THERE. AS WALL OF SNOW COMES IN
CONDITIONS WILL DROP FROM VFR TO IFR. HEAVIEST SNOW EXPECTED TO
FALL APPROXIMATELY 1-3 HOURS AFTER THE SNOW STARTS AT ANY GIVEN
TERMINAL AND BRING TERMINALS DOWN TO BELOW ALTERNATE MINIMUMS
OVERNIGHT. AS PRECIP LIGHTENS LATE TONIGHT EXPECT A MIX TO OCCUR
THROUGH 12Z TUESDAY UNTIL COLDER AIR GETS PULLED IN BEHIND SYSTEM
AND GRADUALLY TURN BACK OVER TO SNOW TOWARD MORNING. KRME WILL
LIKELY STAY IFR THROUGH 18Z TUESDAY AND REMAINING TERMINALS WILL
BECOME MVFR LATE IN THE PERIOD. 

WINDS OUT OF THE SOUTHEAST THIS AFTERNOON AROUND 10-15KTS
OCCASIONALLY GUSTING TO BETWEEN 15-20KTS. SURFACE BOUNDARY MOVES
THROUGH AFTER 12Z TUESDAY WITH WINDS BECOMING LGT OUT OF THE
SOUTHWEST. 

.OUTLOOK...

TUE NGT TO FRI...MVFR/BRIEF IFR IN SCT GUSTY SNOW SHWRS...MOSTLY
NY.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 8 AM EDT TUESDAY FOR PAZ038>040-
     043-044-047-048-072.
NY...WINTER WEATHER ADVISORY UNTIL 8 AM EDT TUESDAY FOR NYZ015>018-
     022>025-044-045-055-056.
     WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 2 PM EDT 
     TUESDAY FOR NYZ046-057-062.
     WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM EDT 
     TUESDAY FOR NYZ009-036-037.

&&

$$
SYNOPSIS...MLJ/MDP/TAC
NEAR TERM...MLJ/TAC
SHORT TERM...MDP
LONG TERM...PVN
AVIATION...PVN