SPC MD 176


MD 0176 Image

Mesoscale Discussion 0176
NWS Storm Prediction Center Norman OK
0559 PM CST Sat Mar 09 2019

Areas affected...Portions of eastern Minnesota...central/southern

Concerning...Winter mixed precipitation 

Valid 092359Z - 100500Z

SUMMARY...Heavy snow, with up to 1 in/hr rates, are possible, mainly
across eastern portions of Minnesota. Elsewhere, patchy areas of
heavy snow, as well as sleet/mixed precipitation and freezing rain
are likely for several hours.

DISCUSSION...Deep-layer warm air/moisture advection continues across
the Upper-Mississippi Valley with the aid of a well-defined surface
low. Modest 850 mb frontogenesis, noted by latest mesoanalysis, has
been associated with a northward propagating band of heavy
precipitation. KMPX, KMKX, and KARX dual-polarimetric radar data
have indicated that a wintry mix of freezing rain, sleet, and
(occasionally) heavy snow has been prevalent with this
aforementioned band. MPING and ASOS reports within the past hour
have indicated that frozen pellets and snow have been the more
dominant precipitation type across eastern Minnesota, with mainly
freezing rain reports across central/southern Wisconsin. 

With the onset of nocturnal cooling, and given sub-zero freezing
wet-bulb surface temperatures across the area (owing to a
sub-saturated sfc-925 mb layer), freezing rain and surface-reaching
frozen hydrometeors are expected to increase over the next few
hours, as supported by the latest HRRR guidance and RAP forecast
soundings. As such, a transition to mainly snow is expected across
northern portions of east-central Minnesota into central/northern
Wisconsin, with a more wintry mix continuing farther south through
at least 03Z. Given the amount of deep-layer ascent present in a
relatively deep/moist dendritic growth zone, occasional bouts of 1
inch/hr snowfall rates will also be possible.

..Squitieri.. 03/09/2019

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


LAT...LON   44989469 45799457 46039414 46059293 45879159 45558981
            44608787 43778731 42768764 42558792 42578917 42909050
            43359175 43799327 44989469 

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