Mesoscale Discussion 1957
NWS Storm Prediction Center Norman OK
1258 AM CST Fri Nov 18 2022
Areas affected...extreme western New York
Concerning...Heavy snow
Valid 180658Z - 181300Z
SUMMARY...2+ inch/hr snowfall rates are expected to continue with
the primary snow band into the mid-morning hours, promoting
near-zero visibility and crippling travel conditions.
DISCUSSION...A mature snow band, roughly 300 km in length, persists
over Lake Erie and is continuing to produce 2+ inch/hr snowfall
rates over and just to the south and east of Buffalo, NY.
Unidirectional vertical wind profiles oriented parallel to Lake
Erie's long axis suggest that the snow band should remain stationary
and continue benefiting from a long fetch of ample low-level
moisture. In addition, colder temperatures aloft overspreading Lake
Erie continue to foster 8-9 C/km low-level lapse rates and 250 J/kg
SBCAPE per 06Z mesoanalysis.
Given a near-saturated, relatively deep dendritic growth zone and
the aforementioned buoyancy, bouts of low-topped convection (perhaps
with occasional lightning flashes) should continue to accompany the
snow band, along with 2+ inch/hr snowfall rates, particularly with
areas closest to the shoreline, where the buoyancy resides. The last
few runs of the HRRR and 00Z HREF ensemble guidance also suggest
that the snow band and accompanying 2+ inch/hr snowfall rates should
persist into at least mid-morning, with crippling travel conditions
and occasional bouts of near-zero visibility expected.
..Squitieri.. 11/18/2022