South Dakota Mesoscale Discussion

Areas affected…East-Central SD…Southern MN…North-Central IA

Concerning…Heavy snow

Valid 090716Z – 091215Z

SUMMARY…A band of heavy snowfall with rates from 1″ to 2″ per hour
will gradually shift eastward across east-central SD, southern MN,
and far north-central IA over the next few hours.

DISCUSSION…Recent mesoanalysis reveals a broad low-level jet
extending from central TX into far southeast SD/far northwest IA.
This low-level jet is contributing to strong warm-air advection and
low to mid-level frontogenesis from southeast SD eastward across
much of IA. This strong mesoscale forcing for ascent has resulted
the development of a band of heavy snowfall (i.e. snowfall rates at
or above 1″ per hour). Regional radar imagery shows this band
extending from east-central SD southwestward across southern MN and
into far northern IA.

Expectation is for this band to gradually shift eastward over the
next several hours in step with mid-level trough responsible for the
low-level jet. Snowfall rates above 1″ per hour will be common
within this band, with instances of rates near 2″ per hour also
possible.

..Mosier.. 02/09/2020

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

ATTN…WFO…ARX…MPX…DMX…FSD…ABR…

LAT…LON 43719587 44319832 44919735 45079602 44799441 44479342
44029288 43669284 43189332 43359484 43719587

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