SPC MD 956


MD 0956 Image

Mesoscale Discussion 0956
NWS Storm Prediction Center Norman OK
0244 PM CDT Sun Jun 21 2020

Areas affected...southern/central Minnesota...northern Iowa...far
southeast South Dakota

Concerning...Severe potential...Watch possible 

Valid 211944Z - 212145Z

Probability of Watch Issuance...60 percent

SUMMARY...Strong to severe storms are expected this afternoon and
evening across portions of southern Minnesota and into northern Iowa
and far southeast South Dakota. Damaging winds and large hail are
the main severe threats as storms move east-southeast. A watch
issuance is possible.

DISCUSSION...Storms have started to develop along enhanced surface
convergence in southern Minnesota. Surface temperatures have warmed
into the low 80s F across the area with dewpoints in the low to mid
60s F. MLCAPE is now 1000-2000 J/kg as steep mid-level lapse rates
have nosed into the area from the southwest and along with the
aforementioned warm/moist boundary layer. Discrete cells including
possible transient supercell structures are possible initially, but
it is likely storms will begin to line out along the stronger
surface convergence. As storms develop they will move east-southeast
with upscale growth into a QLCS possible if not likely, especially
as an upstream mid-level shortwave trough approaches.

Large hail and damaging winds gusts are possible with these storms.
While surface flow is relatively veered, a brief tornado cannot be
ruled out, especially with initial convection near the surface
boundary. The severe wind threat would increase if the storms can
congeal into a QLCS. There is potential for cold pool development
given the orientation of the surface boundary to the upper-level
flow and ongoing cloud cover just north of the developing

..Nauslar/Guyer.. 06/21/2020

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


LAT...LON   42819524 42989643 43049729 43509762 44329686 44599578
            44789471 44989383 45069342 45049285 44079258 43079292
            42809367 42819524 

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