MD 1292 CONCERNING SEVERE THUNDERSTORM WATCH 410… FOR CENTRAL AND SOUTHERN MN INTO WESTERN AND CENTRAL WI
Mesoscale Discussion 1292
NWS Storm Prediction Center Norman OK
0137 AM CDT Wed Jul 12 2017
Areas affected...Central and southern MN into western and central WI
Concerning...Severe Thunderstorm Watch 410...
Valid 120637Z - 120900Z
The severe weather threat for Severe Thunderstorm Watch 410
continues.
SUMMARY...Strong/damaging wind gusts and large hail remain
severe-weather threats across WW 410 as storms continue to develop
and spread to the east in central and southern MN. A new severe
thunderstorm watch is being considered to the east of WW 410 across
parts of northern and central WI.
DISCUSSION...Time lapse of mosaic radar imagery during the early
overnight indicated storms have been clustering across the northern
portion of WW 410 in central MN (Douglas County to Kanabec County)
and tracking to the east at 35-40 kt. Meanwhile, a smaller cluster
of storms was moving east through McLeod County, MN. Additional
storms were developing to the north-northeast into west-central WI
(Trempealeau to Monroe counties) with rapid cloud-top cooling per IR
satellite imagery. Modest southwesterly low-level winds (20-25 kt)
across southern MN will continue advect moisture into southern MN
and western/central WI with surface dew points in the upper 60s to
70 F. This combined with steep midlevel lapse rates will support
additional destabilization (MUCAPE increasing to 2000-3500 J/kg)
across WI through 12Z. This thermodynamic improvement is
represented in the special 06Z MPX sounding, which also had a 4.2
g/kg increase since 00Z of the mean mixing ratio - now at 17.8 g/kg.
Aside from the 00Z Hi-res WRF-ARW and the recent two runs of the
HRRR (04Z/05Z), CAMS lack a good representation of ongoing storms
across the upper MS Valley. Given a modest low-level jet and
westerly flow aloft across the northern tier of the U.S., the
potential exists for ongoing storms in central MN to evolve into a
forward propagating north-south oriented line of storms, as this
activity reaches western WI between 08-09Z. Convective trends will
be monitored in the short term, and if bowing segments develop, then
a new WW would be needed to the east of WW 410.
..Peters.. 07/12/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...DLH...ARX...MPX...FSD...ABR...
LAT...LON 44639607 45439624 46189493 46249414 46249312 45959167
45779048 45488972 45268942 44408911 43608909 43568967
43589133 44109189 44169411 44239492 44639607
from SPC Mesoscale Discussions http://bit.ly/2uh99vP
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