ZCZC SPCSWOMCD ALL
ACUS11 KWNS 181800 
SPC MCD 181800 
NYZ000-182200-

MESOSCALE DISCUSSION 1925
NWS STORM PREDICTION CENTER NORMAN OK
1200 PM CST TUE NOV 18 2014

AREAS AFFECTED...WRN NY STATE

CONCERNING...HEAVY SNOW 

VALID 181800Z - 182200Z

SUMMARY...HEAVY SNOW RATES OF 3-4" PER HOUR WILL CONTINUE FOR NEXT
4-6 HOURS JUST S OF BUF.  A SWD SHIFT AND WEAKENING OF THE BAND IS
EXPECTED TO BEGIN AFTER 00Z.

DISCUSSION...A STEADY LAKE-EFFECT SNOW BAND PERSISTS ALONG THE
LONG-AXIS ORIENTATION OF LAKE ERIE...INTO SUBURBAN AREAS IMMEDIATELY
S OF THE NEARLY PERFECT ALONG-LAKE FETCH AND WEAK VERTICAL SHEAR
BELOW 700 MB WILL MAINTAIN THE STRONG SNOW BAND FOR SEVERAL MORE
HOURS.VERY LARGE AIR-LAKE TEMPERATURE DIFFERENCES ARE DRIVING
INTENSE CONVECTIVE MIXING WITHIN THE LAKE PLUME...AS EVIDENCED BY
THE 30-40 KT WNW-NW SURFACE WINDS AND STRONG CONVERGENCE INTO THE
BAND OVER THE NE PART OF LAKE ERIE.  THERMAL PROFILES ARE MOST
FAVORABLE FOR THE DEEPEST CONVECTION NOW /AS EVIDENCED BY A FEW
LIGHTNING FLASHES IN THE PAST HOUR/...AND PROFILES SHOULD REMAIN
FAVORABLE THIS AFTERNOON.  NEAR OR AFTER 00Z...EQUILIBRIUM LEVELS
WILL LOWER AND THE DEPTH OF THE LAKE BAND WILL BEGIN TO
DIMINISH.....COINCIDENT WITH VEERING OF THE MIDLEVEL FLOW AND A
RESULTANT SWD SHIFT OF THE BAND AS A MIDLEVEL TROUGH PROGRESSES E OF
LAKE ERIE.  THUS...THE VERY HEAVY SNOWFALL RATES ARE EXPECTED TO
PERSIST FOR THE NEXT 4-6 HOURS IMMEDIATELY S OF BUF WHERE
EXCEPTIONAL SNOW TOTALS NEAR 4 FEET HAVE ALREADY BEEN OBSERVED.

..THOMPSON.. 11/18/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BUF...

LAT...LON   42737933 42987867 43047830 42997790 42857782 42737798
            42617834 42507888 42427927 42327969 42357989 42537987
            42737933 

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