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Mesoscale Discussion 0347
NWS Storm Prediction Center Norman OK
0626 AM CDT Sun Apr 12 2020
Areas affected...Parts of northeastern Nebraska...southeastern South
Dakota...northwestern Iowa and southwestern Minnesota
Concerning...Heavy snow
Valid 121126Z - 121530Z
SUMMARY...A band of heavy snow is expected to develop across the
region this morning, with rates of 1-2 inches per hour increasingly
likely by 9-11 AM CDT.
DISCUSSION...As upstream mid-level troughing gradually pivots into
the northern High Plains, models indicate that lower/mid
tropospheric frontogenetic forcing will intensify through 12-16Z
across the middle Missouri Valley. It appears that this will also
coincide with increasing upper divergence within the right entrance
region of a high-level jet, to support strengthening deep-layer
lift, including through the layer favorable for large dendritic ice
crystal growth, within at least a narrow corridor across
northeastern Nebraska into southwestern Minnesota. Thermodynamic
profiles across this region are already generally entirely below
freezing, with gusty post-frontal surface winds beneath a 30-40 kt
north-northeasterly 850 jet contributing to continuing low-level
cold advection. Supported by precipitable water on the order of .5
to .7 inches, sustained heavy snow rates of 1 to 2 inches per hour
appear possible for a several hour period this morning.
..Kerr.. 04/12/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...FSD...OAX...LBF...
LAT...LON 42989820 44269545 44279459 43729446 43149610 41849914
42989820
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