Mesoscale Discussion 1021
NWS Storm Prediction Center Norman OK
0834 PM CDT Tue Jun 13 2017
Areas affected...Eastern South Dakota into Minnesota... northwest
Iowa...eastern North Dakota
Concerning...Tornado Watch 326...327...
Valid 140134Z - 140230Z
The severe weather threat for Tornado Watch 326, 327 continues.
SUMMARY...Damaging winds, hail, and brief tornadoes continue to be
possible across the watch area.
DISCUSSION...The bulk of the storm activity has now consolidated
into a QLCS, from southeast ND into eastern SD and far northeast NE.
A very moist and unstable air mass remains ahead of these storms
along and south of the warm front which exists across central MN.
The air mass is also unstable in an elevated sense north of the
boundary, with 40-50 kt 850 mb flow present.
The northern portion of the QLCS is a bit more favorably oriented
relative to the deep-layer shear, and radar shows areas of rotation
along the gust front. Strong to severe wind gusts and/or brief and
likely weak tornadoes remain possible.
To the south, outflow appears to be surging well ahead of the main
storm cores, but recent radar trends show an increasing hail threat,
from near the Sioux Falls area southward into Nebraska. The 00Z OAX
sounding shows a very unstable profile supportive of large hail.
Severe storms are expected to persist across the watch area for a
few more hours. To the east of the watch, convective inhibition
increases, and may result in weakening storms. Therefore, it is
unclear if a new watch will be needed.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 42289765 43489757 44159727 44729698 45099698 45539744
46389868 46939907 47489852 47739789 47689621 47339456
46859398 46029390 44849405 43669460 42869516 42409602
42169659 42079700 42289765