SPC MD 302



MD 0302 CONCERNING WINTER MIXED PRECIPITATION FOR NORTH CENTRAL THROUGH NORTHEAST NEBRASKA…CENTRAL AND EASTERN SOUTH DAKOTA AND SOUTHERN MINNESOTA

MD 0302 Image

Mesoscale Discussion 0302
NWS Storm Prediction Center Norman OK
0234 AM CDT Thu Apr 11 2019

Areas affected...north central through northeast Nebraska...central
and eastern South Dakota and southern Minnesota

Concerning...Winter mixed precipitation 

Valid 110734Z - 111330Z

SUMMARY...Areas of moderate to heavy snow including blizzard
conditions with rates up to or locally exceeding 1 inch per hour are
expected to continue through the early morning from north central
Nebraska, central and eastern South Dakota into a portion of
southern Minnesota. A mix of freezing rain and sleet will likely
continue from northeast Nebraska into far southern Minnesota.

DISCUSSION...Early this morning, bands of mostly snow continue from
north- central NE into central and eastern SD and a portion of of
south- central and southwest MN. The activity is associated with
strong ageostrophic forcing within the exit region of an intense
(140+ kt) upper jet. This zone of strong upper forcing will advance
northward through the Northern Plains and upper MS Valley this
morning with attendant surface low moving from northeast KS to
southeast NE by 12Z. On the mesoscale, there appears to be a
vorticity maximum currently moving northward through eastern NE.
This feature will coincide with corridor of enhanced frontogenetic
forcing within deformation zone, supporting development of organized
snow bands from north central NE into central and eastern SD. In
addition the strong pressure gradient north of the low pressure
track will continue to promote wind gusts occasionally from 40-45 kt
creating blizzard conditions in this region. 

Farther south from northeast NE into southern MN, a broad zone of
warm advection associated with a 60-70 kt low-level jet has resulted
in a melting layer aloft that should continue to advance slowly
north. In addition, steep lapse rates, up to 1000 J/kg MUCAPE, and
strong isentropic ascent are supporting numerous thunderstorms. Some
of the heavy snow now occurring over southwest MN is convectively
enhanced. However, this precipitation should gradually change to
sleet and freezing rain as the melting layer develops north with
time.

..Dial.. 04/11/2019

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

ATTN...WFO...ARX...MPX...DMX...FSD...OAX...ABR...LBF...UNR...

LAT...LON   44199216 43659417 43049621 41989812 41710055 42400129
            43690115 45099873 45529612 45249327 44739211 44199216 

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