SPC MD 62



MD 0062 CONCERNING HEAVY SNOW FOR LEE OF LAKE ONTARIO (SOUTHERN JEFFERSON…NORTHERN OSWEGO…AND LEWIS COUNTIES)

MD 0062 Image

Mesoscale Discussion 0062
NWS Storm Prediction Center Norman OK
0251 AM CST Thu Jan 31 2019

Areas affected...Lee of Lake Ontario (southern Jefferson...northern
Oswego...and Lewis Counties)

Concerning...Heavy snow 

Valid 310851Z - 311445Z

SUMMARY...High snowfall rates (2"+/hr) are expected within a single
snow band in lee of Lake Ontario through the remainder of the night
and this morning.  This snow band will shift southward through 12Z
and should stall near and south of the Jefferson/Oswego Counties
line into northern Oswego and southern Lewis Counties through at
least the morning.

DISCUSSION...Trends in mosaic radar and individual radar imagery
indicated a southward shift of a lake effect snow band over and in
lee of Lake Ontario has been underway since about 07Z.  Surface
observation along the north shore of the lake at CWQP (Point Petre,
ON) showed the wind had veered to westerly with the equatorward
passage of this band.  The passage of a surface trough across
southern ON and far southern QB, while the northern extent of an
anticyclone expands into the lower Great Lakes through this morning,
should maintain a westerly long-fetch convective snow band across
the long axis and in lee of Lake Ontario.  Most CAMs suggest the
southward shift of the band will persist through 12Z across southern
Jefferson and northern Lewis Counties.  General agreement then
exists indicating the band will stall near and south of the
Jefferson/Oswego Counties line into northern Oswego to southern
Lewis Counties through the morning.

Steep low-level lapse rates per forecast soundings and persistent
low-level convergence across the long axis of Lake Ontario suggest
high snowfall rates in lee of the eastern part of this lake, while
upslope flow inland will further enhance these snowfall rates.

..Peters.. 01/31/2019

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   43847633 43847583 43757535 43567524 43417546 43337576
            43427627 43457651 43647629 43847633 

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