Mesoscale Discussion 0124
NWS Storm Prediction Center Norman OK
0458 PM CST Mon Feb 17 2020
Areas affected...Northeast Iowa...Southeast Minnesota...and
South-Central Wisconsin
Concerning...Heavy snow
Valid 172258Z - 180200Z
SUMMARY...Moderate to occasional heavy snow should continue the
develop this afternoon/evening, with snowfall rates approaching 1
in/hr.
DISCUSSION...A broad area of low-level theta-e advection has been
persistent across northern Iowa into southern Minnesota/Wisconsin
for much of the day. This process has resulted in a gradual warming
of surface temperatures to near or just above freezing, perhaps 1-2
F warmer than most model solutions were indicating. In addition to
broad isentropic ascent, a focused region of greater mid-level
ascent and expanding area of precipitation is occurring across
central/north-central Iowa in association with a compact mid-level
short-wave trough. Many areas are experiencing rain, with perhaps
some mixed precipitation. However, where temperatures have remained
at or near freezing, moderate to occasional heavy snow is occurring,
mainly across parts of southwest Wisconsin and far northeast Iowa.
Considerable uncertainty exists in the near-term placement and
persistence of precipitation types across the region. Projections of
observational analysis and short-term model model guidance would
suggest snowfall potential should maximize as the focused area of
ascent becomes colocated with low-level thermal profiles that favor
snow. Therefore, the most likely area for moderate to heavy snow
(with rates approaching 1 in/hr) appears confined to a narrow
corridor from southwest Wisconsin into parts of east-central
Wisconsin for the remainder of this afternoon into the early
evening.
Farther west, across northeast Iowa and southeast/south-central
Minnesota, warmer surface temperatures should limit snowfall
potential. However, a period of brief moderate to heavy snow may
occur as surface temperatures approach freezing with the advancing
cold front.
..Karstens.. 02/17/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...ARX...MPX...DMX...
LAT...LON 43268824 42918938 42859040 42839154 43099286 43589348
43979387 44369356 44319110 44588997 45048797 44398765
43788786 43268824
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