Mesoscale Discussion 1227
NWS Storm Prediction Center Norman OK
0531 PM CDT Fri Aug 03 2018
Areas affected...Central and Southern Minnesota
Concerning...Severe potential...Watch unlikely
Valid 032231Z - 040100Z
CORRECTED FOR AREAS AFFECTED.
Probability of Watch Issuance...20 percent
SUMMARY...Isolated severe gusts are possible for the next few hours,
with a decreasing severe threat as the boundary layer stabilizes. A
WW issuance is not anticipated at this time.
DISCUSSION...Convection, initiated by a small 500 mb mid-level
shortwave trough/vortmax along the northeast South Dakota/southeast
North Dakota border, has recently grown upscale into an MCS along
the South Dakota/Minnesota border. The ambient environment is
characterized by 3000-4000 J/Kg MUCAPE (fueled mainly by steep low
and mid-level lapse rates and rich sfc-925 mb moisture), and 40+
knots of effective bulk shear. 700 mb warm air advection is also
prevalent downstream of the MCS, suggesting that forcing for ascent
should support the continuance of the MCS for at least a few more
hours. Even so, relatively drier air in the 850-700 mb layer
downstream of the MCS suggests that convection should undergo a
weakening trend as the boundary layer decouples, likely cutting off
the MCS from access to better moisture.
As such, any severe threat that may occur from the present moment is
expected to be relatively short in duration and isolated, with
damaging wind gusts the primary threat. A WW issuance is currently
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 45719607 45579620 44939681 44689636 44589603 44599522
44589431 44609354 44839311 45289312 45679325 45939417