MESO: Mesoscale Discussion 2359

ACUS11 KWNS 230308
SWOMCD
SPC MCD 230308
MEZ000-NHZ000-VTZ000-NYZ000-230815-

MESOSCALE DISCUSSION 2359
NWS STORM PREDICTION CENTER NORMAN OK
0908 PM CST TUE NOV 22 2011

AREAS AFFECTED...NERN NY...MUCH OF NH AND VT...EXTREME W CNTRL ME

CONCERNING...HEAVY SNOW

VALID 230308Z - 230815Z

HEAVY SNOW WILL DEVELOP BY 06Z WITH RATES AROUND 1 IN/HR EXPECTED.
LOCAL AREAS OF 2 IN/HR WILL BE POSSIBLE IN HEAVIER BANDS. ACROSS
SOUTHERN PORTIONS OF THE MCD AREA...SNOW MAY MIX WITH SLEET AT
TIMES.

LIGHT SNOW OR A WINTRY MIX HAD BEGUN TO MOVE INTO PORTIONS OF NERN
NY AS OF 02Z. PRECIPITATION IS EXPECTED TO CHANGE TO ALL
SNOW...PERHAPS MIXING WITH SOME SLEET AT TIMES WITHIN THE NEXT HOUR
OR SO AS THE SFC WET BULB ZERO LINE RESIDES JUST NORTH OF ALB TO NE
OF RME THEN EXTENDING NW TOWARD ART WHERE LIGHT FREEZING RAIN WAS
BEING REPORTED. MOISTURE WILL CONTINUE TO ADVECT NWD TONIGHT ON
STRONG S/SELY FLOW. DEVELOPING IN ACCORDANCE WITH THIS MOISTURE
SURGE AND APPROACHING UPPER LEVEL TROUGH/VORT MAX...STRONG
WAA/FRONTOGENESIS IS EXPECTED BETWEEN 850-700 MB. FORECAST SOUNDINGS
ACROSS THE REGION SHOW A SLIGHT WARM NOSE IN THIS LAYER NEAR 0 C TO
+1 C /DEEPER ACROSS SRN PORTIONS OF THE MCD AREA/.
HOWEVER...TEMPERATURES BELOW 850 MB WILL REMAIN COLD ENOUGH TO ALLOW
PRECIPITATION TO REMAIN FROZEN OR REFREEZE...HENCE THE POSSIBILITY
OF A SNOW/SLEET MIXTURE AT TIMES. SOUNDINGS ALSO INDICATE A FAIRLY
SHALLOW DENDRITIC GROWTH ZONE...AROUND 3KFT. THIS SHOULD NOT BE A
PROBLEM WHERE SNOWFALL RATES ARE EXPECTED TO BE GREATEST GIVEN A
NEAR ISOTHERMAL PROFILE BELOW THE GROWTH ZONE WITH TEMPERATURES NEAR
-9 C TO -6 C FROM AROUND 16 KFT AGL TO AROUND 1.6 KFT AGL.
ADDITIONALLY...INTENSE 700-500 MB FRONTOGENESIS WILL AID IN DEEP
LAYER ASCENT THROUGH THE GROWTH LAYER...FURTHER ENHANCING SNOWFALL
RATES.

..LEITMAN.. 11/23/2011

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

ATTN...WFO...GYX...BOX...BTV...ALY...BGM...BUF...

LAT...LON 43777542 44187524 44437497 44837429 44927346 44977249
44887149 44717099 44487078 44257076 43767084 43397127
43137197 43027283 43107358 43167440 43237487 43407534
43777542

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