Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 012331
AFDBGM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
631 PM EST SUN FEB 1 2015

.SYNOPSIS...
A SIGNIFICANT WINTER STORM WILL IMPACT THE REGION OVERNIGHT AND
MONDAY. ONCE THIS STORM MOVES OFF THE COAST MONDAY
NIGHT...BITTERLY COLD WEATHER WILL SET IN AGAIN...LASTING THROUGH
TUESDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
6 PM UPDATE...DID AN UPDATE OF THE WINTER WEATHER MESSAGE ISSUED
FOR OUR WINTER STORM WARNINGS TO REFINE TIMING OF THE BEGINNING OF
THE WINTER STORM. MADE SOME MINOR ADJUSTMENTS TO THE TIMING AND
INTENSITY OF SNOW SHIELD AS IT CONTINUES TO PUSH NORTH AND EAST.
LOOKING AT THE LATEST GUIDC...WE MAY HAVE TO ADJUST SNOW AMOUNTS
UP ACROSS SYR-UCA-RME AREAS AND LOWER AMNTS IN NE PA. HEAVIER SNOW
MAY REACH FARTHER NORTH THAN WE HAVE ADVERTISED AT THIS POINT. THE
ZR/IP LINE CUD MAKE A RUN FOR THE NY BORDER LATE TONIGHT/EARLY
MONDAY. WE WILL CONTINUE TO MONITOR LATEST GUIDC AND MAKE CHANGES
IF ENUF SCIENTIFIC EVIDENCE HOLDS.

ANOTHER CONCERN IS THAT HRRR IS SLOWER THAN OUR LOCAL
WRF...RAP...NAM12 AND WRF_NMM AND WRF_ARW IN BRINGING IN THE
HEAVIER SNOW LATER TONIGHT. WE WILL AGAIN MONITOR THE SNOW SHIELD
AS IT PROGRESSES NEXT FEW HOURS.

DYNAMICS FOR THE EVENING AND OVERNIGHT ARE INCREASING WAA OR ISENTROPIC
LIFT AHEAD OF AN UPPER LEVEL SHORT WAVE TROF WHICH MAKES IT TO OH
TO THE ERN LAKES BY 12Z. HENCE WE WILL SEE LIFTG AS AIR FLOWS UP
THE ISENTROPES IN ADDITION TO THE ISENTROPES BODILY RISING IN
ADVANCE OF THE SHRT WAVE TROF. HENCE THE HEAVIEST SNOW WILL FALL
BETWEEN 6Z AND 12Z MOST AREAS. IN NE PA...A SLIGHTLY ABOVE
FREEZING LAYER LIKELY WILL SNEAK NORTH AS PER NAM...GFS AND SREF
MODEL SOUNDINGS AND REACH INTO NE PA BETWEEN 9Z AND 12-14Z. HOW
FAR N THIS MAKES IT IS UNCERTAIN...BUT MODELS INDICATE AT LEAST
KAVP...POSSIBLY THE PA/NY BORDER BY 12-14Z. AGAIN WILL MONITOR AND
WITH 10 PM UPDATE MIGHT HAVE TO LOWER AMNTS IN NE PA. NC NY MAY
SEE THE MOISTURE FROM STRG THERMAL AND MOISTURE ADVTNS REACH UP
THERE AND WITH HIGHER SNOW RATIOS AMNTS CUD BE HIGHER THAN WHAT WE
HAVE. GRIDS UPDATED. LEFT SNOW AMOUNTS ALONE AS WAITING FOR MORE
GUIDC AND THE CHARACTER OF THE EVOLVING RADAR TRENDS VS THE HI RES
MODEL RADAR TRENDS.

PREVIOUS DSCN BELOW...
3 PM SUN UPDATE... THE LEADING EDGE OF THE STEADIER -SN EXTENDS
FROM OUR WRN FINGER LAKES/CNTRL SRN TIER ZNS...DOWN INTO PTNS OF
NE PA ATTM. IT WILL CONTINUE TO EXPAND NEWD THROUGH THIS
EVE...REACHING THE MOHAWK VLY AND SRN TUG HILL RGNS BY ARND 02Z.
IT`S PSBL THIS COULD HAPPEN A BIT QUICKER...AS EXISTING LOW-LVL
MOISTURE ACRS CNY/NE PA COULD AID IN THE TOP-DOWN MOISTENING PROCESS.

THE MAIN EVENT STILL LOOKS TO BE OVERNIGHT AND MON MRNG (ROUGHLY
03-15Z). IT IS IN THIS TIME FRAME THAT EXCELLENT COUPLED JET
STRUCTURE DYNAMICS TAKE HOLD...TO HELP TRANSPORT A MOISTURE-LADEN
AMS INTO THE NERN U.S. (BLENDED TPW IMAGERY SHOWING THE SOURCE
NICELY OVER THE WRN GOMEX/LWR MS/OH VLYS)...AND SET THE STAGE FOR
STG FORCED ASCENT (EXCELLENT LOW-LVL SPEED CONVERGENCE AND A TIGHT
THERMAL GRADIENT LEADING TO PRONOUNCED FGEN OVER A DEEP LYR).
WHERE PTYP REMAINS ALL SNOW...RATES OF 1-2"/HR COULD OCCUR FOR A
SUBSET OF THIS TIME FRAME (MAINLY 06-12Z).

THE MAIN COMPLICATING FACTOR REMAINS PTYP. THE 12Z GFS IN
PARTICULAR MADE A SLGT NWD JOG AGN IN THE CYCLONE TRACK...WITH THE
LEADING EDGE OF THE WARM NOSE ALOFT (850-875 MB) MAKING A RUN AT
THE PA/NY BORDER BY 12Z. SREF THERMAL PROFILES GIVE SOME CREDENCE
TO THIS SCENARIO. ALTHOUGH THE LATEST NAM/RGNL GEM/EC RUNS ARE
SOMEWHAT COLDER...THE AMPLIFIED NATURE OF THE S/WV SEEN IN WATER
VAPOR IMAGERY ATTM OVER THE MIDWEST CERTAINLY OPENS THE DOOR TO
THE PSBLTY OF A MORE NWD STORM TRACK/MORE EXPANSIVE SHIELD OF
MIXED PCPN EARLY MON. OUT OF RESPECT TO THE GFS...WHICH HAS BEEN
CONSISTENTLY SHOWING THIS TREND FOR SVRL RUNS NOW...WE DID NUDGE
SNOWFALL AMTS DOWN SLIGHTLY IN OUR FAR SRN ZNS...AND
CORRESPONDINGLY UPWARD IN OUR NRN TIER OF ZNS. OVERALL...THIS
DIDN`T CHG TOTAL ACCUMS APPRECIABLY. EVEN IF THE SOMEWHAT WARMER
SCENARIO VERIFIES...WE STILL FEEL THAT THERMAL/MOISTURE ADVECTION
WILL BE STG ENUF OVERNIGHT TO PRODUCE A QUICK 4-8" OF SNOW BEFORE
DAYBREAK ACRS MUCH OF THE CWA.

DURG THE DAY MON...AS THE SFC LOW TRANSLATES TWDS THE NJ COAST/SRN
LONG ISLAND...COLDER AIR WILL SPREAD SEWD THROUGH THE RGN BY AFTN.
CONSEQUENTLY...ANY AREAS OF MIXED PCPN SHOULD BE BACK OVER TO SNOW
BY 15-18Z. AT THE SAME TIME...MOST OF THE MODELS ARE SHOWING A 3-6
HR WINDOW FOR DEFORMATION TYPE BANDING (MAINLY FROM ABT 15-21Z)...WITH
THE MID-LVL DRY SLOT CLOSE ENUF FOR REDUCED STABILITY ALOFT...AND
AN INCREASING 700-500 MB FGEN BAND SHIFTING ACRS CNY/NE PA. THE
BEST CHC FOR MORE PERSISTENT SNOW BANDING (ADDTNL ACCUMS) SHOULD
BE NEAR AND E OF THE I-81 CORRIDOR. WHEN ALL IS SAID AND DONE...WE
STILL EXPECT STORM TOTAL SNOWFALL OF 6-10" IN OUR FAR NRN AND SRN
ZNS...WITH A SLIGHTLY HVYR STRIPE OF 8-12" IN THE MIDDLE (LOCALLY
HIER AMTS (UP TO ARND 14") MOST LIKELY TWDS
CHENANGO/OTSEGO/DELAWARE CNTYS).

AS ALLUDED TO ABV...TEMPS WILL BE FALLING SHARPLY MON AFTN...WITH
BITTERLY COLD WIND CHILLS BCMG MORE OF AN ISSUE WITH TIME. MORE ON
THIS IN THE FOLLOWING SXN.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
ARCTIC ARE WILL SPILL BACK DOWN FROM CANADA ON THE BACK SIDE OF
THE CYCLONE. APPARENT TEMPERATURES FOR THE NORTH AND EAST RANGE
FROM -10F TO -18F OVERNIGHT, BORDERLINE FOR A WIND CHILL ADVISORY.
WE WON`T CONSIDER AN ADVISORY AT THIS POINT, AS WE DON`T WISH TO
DISTRACT FROM THE CURRENT STORM SCENARIO.

AFTER A DRY, COLD DAY TUESDAY...INCLUDING SOME WEAK LAKE ACTIVITY
TO THE NORTHWEST...ANOTHER WAVE WILL DIP DOWN ACROSS NY LATE
TUESDAY INTO WEDNESDAY. THIS SYSTEM WILL HAVE LIMITED MOISTURE BUT
SHOULD STILL PRODUCE 2 TO 3 INCHES OF NEW SNOW.

THE REAL IMPACT OF THE WAVE WILL BE TO USHER IN ANOTHER ARCTIC
BLAST FOR THURSDAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A LARGE SCALE TROF OVER THE NORTHEASTERN UNITED STATES WILL
CONTINUE TO KEEP OUR TEMPERATURES WELL BELOW NORMAL.

A WEAK DEPARTING CYCLONE WILL SLIDE EASTWARD WEDNESDAY NIGHT,
BRINGING ADDITIONAL SNOW SHOWERS AND A SECOND SHOT OF ARCTIC AIR.

THURSDAY APPEARS PARTICULARLY COLD. 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.

SOME MODERATION IS POSSIBLE ON SATURDAY AS A SOUTHERN RIDGE
EXPANDS INTO THE MID-ATLANTIC REGION. HOWEVER TEMPERATURES WILL
REMAIN BELOW NORMAL.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
A POWERFUL STORM WILL SPREAD SNOW FROM SOUTHWEST TO NORTHEAST OVER
THE NEXT SEVERAL HOURS. THE SNOW WILL ARRIVE IN AVP AND ELM
BETWEEN 18Z AND 19Z, BGM AND ITH BETWEEN 20Z AND 22Z, AND RME AND
SYR BETWEEN 01Z AND 03Z.

THE SNOW WILL LOWER VISIBILITIES TO BETWEEN 1SM AND 2SM, WITH
LOWER VISIBILITIES POSSIBLE OVERNIGHT AS THE SNOW INTENSIFIES.
CEILINGS WILL LIKELY BEGIN AS MVFR AND TREND DOWNWARD TO IFR
OVERNIGHT. A LONG PERIOD OF IFR CONDITIONS IS FORECAST BEFORE THE
ENDS LATE MONDAY AFTERNOON.

WINDS WILL SHIFT TO THE EAST AT 5 TO 10 KNOTS.

OUTLOOK...

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 UNTIL 4 PM EST MONDAY FOR PAZ038>040-043-
     044-047-048-072.
NY...WINTER STORM WARNING UNTIL 4 PM EST MONDAY FOR NYZ015>018-
     022>025-036-037-044>046-055>057-062.
     WINTER STORM WARNING UNTIL 4 PM EST MONDAY FOR NYZ009.

&&

$$
SYNOPSIS...MLJ
NEAR TERM...DJN/MLJ
SHORT TERM...DJP
LONG TERM...DJP
AVIATION...DJP






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