SPC MD 295

SPC MD 295


Mesoscale Discussion 0295
NWS Storm Prediction Center Norman OK
0504 PM CDT Sun Mar 24 2024

Areas affected…Parts of southeastern Minnesota and
northern/central Wisconsin

Concerning…Heavy snow

Valid 242204Z – 250300Z

SUMMARY…A snowband with eventual heavy rates near 1-1.5 inch/hour
is expected to move northward across parts of southeastern Minnesota
and northern/central Wisconsin into tonight. The onset of heavier
rates is expected in the 23Z-04Z time frame.

DISCUSSION…KARX radar data and mesoanalysis as of 22Z indicate a
well-defined frontogenetic band moving northward across far northern
IA, southern MN, and southwest WI. This band is generally located
along the northern periphery of a swath of 40-50-kt 1-km flow per
regional VWP data, which also shows a large clockwise-curved
low-level hodograph — indicative of strong low-level warm-air
advection. The associated low-level warm nose is yielding melting of
hydrometeors beneath the snowband (and a robust bright-banding
signature), with light to moderate snowfall rates thus far.

With time, the band will continue northward into a region of colder
low-level air, and additional low-level cooling should be aided by
nocturnal effects and wet-bulbing. As a result, snowfall rates
should eventually increase to near 1-1.5 inch/hour as the snowband
moves into the increasingly cold air. There is some uncertainty on
how widespread these heavier rates will be (especially in the next
couple of hours), due to the marginally cold temperatures and much
of the frontogenetic ascent remaining below the dendritic growth
zone. Nevertheless, the heavy-snow potential should increase in the
23Z-04Z time frame.

..Weinman.. 03/24/2024

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


LAT…LON 44059117 43959249 43979386 44239442 44649458 45019452
45409416 45709334 45959186 45928898 45698837 45288825
44718867 44218993 44059117

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