Subj : MESO: Mesoscale Discussion 0112
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jan 28 2023 03:52:23

ACUS11 KWNS 280352
SWOMCD
SPC MCD 280351=20
IAZ000-NEZ000-SDZ000-280945-

Mesoscale Discussion 0112
NWS Storm Prediction Center Norman OK
0951 PM CST Fri Jan 27 2023

Areas affected...portions of southern and eastern South
Dakota...northern Nebraska into far northwestern Iowa

Concerning...Heavy snow=20

Valid 280351Z - 280945Z

SUMMARY...Periods of heavy snow with rates of 1 inch per hour are
possible late this evening and overnight along a stationary front
across portions of the central and northern Plains.

DISCUSSION...Across the central and northern Plains, late evening
moisture-channel imagery showed a subtle vort max/shortwave trough
ejecting eastward out of the central/northern Rockies. Weak height
falls associated with the upper-level feature are forecast to
progress slowly eastward overnight colocated with a weak lee low and
quasi-stationary front stretching from western SD toward NE/IA. This
broad ascent has supported the development of light to occasionally
moderate snow across portions of SD/NE over the last several hours.
Increasing mid-level ascent from the vort max coupled with
isentropic lift and enhanced convergence along the quasi-stationary
front will support additional precipitation
development/intensification over the next couple of hours.

Area RAP sounding show increasing surface cold advection to the
north of the quasi-stationary front reinforcing the sub-freezing
airmass at the surface and lowest few kilometers. Focused low and
mid-level ascent over the cold airmass will favor efficient snow
generation with ratios in excess of 15:1. HREF probabilities and
current observations suggest mesoscale banding within the broader
moderate precip shield will likely support periodic heavy snow with
rates near 1 inch/hour overnight. Heavy snow is most likely from
portions of southern/southeastern SD from 05-09z shifting eastward
into northeastern NE and far northwestern IA. Heavy snow may linger
for a few hours near 12z farther east, but confidence in the
heaviest snow decreases early this morning as ascent begins to wane.

...Lyons/Grams.. 01/28/2023

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!45GaCOyznun_PhafOiIXBHNU0INPpkU2926w7fm6UztsnHIIUH_wI86hCQXk0rZ58KwlNT9np=
WGrUVziEXZARqSIl6U$  for graphic product...

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...

LAT...LON   43220153 43520178 43740143 43810075 43629849 43619732
            43549652 43239600 42649598 42229626 42059662 42039710
            42069787 42249902 42700034 43220153=20


=3D =3D =3D
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