SPC MD 1149

MD 1149 CONCERNING SEVERE THUNDERSTORM WATCH 344... FOR NORTHEAST SOUTH DAKOTA INTO CENTRAL MINNESOTA AND NORTHWEST WISCONSIN

Mesoscale Discussion 1149
NWS Storm Prediction Center Norman OK
0951 PM CDT Wed Jul 08 2020

Areas affected...northeast South Dakota into central Minnesota and
northwest Wisconsin

Concerning...Severe Thunderstorm Watch 344...

Valid 090251Z - 090445Z

The severe weather threat for Severe Thunderstorm Watch 344
continues.

SUMMARY...The risk for severe hail and wind continues for much of WW
344. Developing thunderstorms across northeast South Dakota will
pose an increasing risk for severe weather into western Minnesota.

DISCUSSION...Convective initiation has occurred along a stationary
boundary/surface trough draped across northeast SD. These storms are
developing in an environment that remains supportive for severe
convection with ample instability and 30-40 knots of effective bulk
shear. Initially discrete storms will pose the risk for both severe
hail and strong winds. A transition to primarily a wind threat is
expected as along-boundary deep layer shear and long storm residence
times on the initiating boundary favor upscale growth into more
linear storm modes. These storms should move into western MN within
the coming hours. 

Thunderstorms developing across central MN will pose some severe
potential given favorable shear and instability that remains in
place. However, the duration/coverage of this severe threat is
uncertain as storms move into an area recently contaminated by prior
convection.  

To the east, thunderstorms across east-central MN and northwest WI
continue to grow upscale with linear segments noted in recent
regional radar imagery. Organized convective outflow has largely
been sub-severe, likely due to a cooling boundary layer/marine
boundary layer influences, and weaker deep-layer shear. However,
spurious downburst winds, and even severe hail, remain possible with
any stronger updraft pulses. These storms may reach as far east as
the western U.P. of MI, but given weakening MLCAPE and deep-layer
shear with eastward extent, a watch extension is not anticipated.

..Moore.. 07/09/2020

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

ATTN...WFO...MQT...GRB...DLH...MPX...FGF...FSD...ABR...

LAT...LON   44669841 45569685 46819510 47609297 47419084 47018891
            46378884 45858915 45669142 45169326 44549555 44339795
            44669841 

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