MD 1474 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SOUTH-CENTRAL…SOUTHEAST AND EAST-CENTRAL SD
Mesoscale Discussion 1474
NWS Storm Prediction Center Norman OK
0248 AM CDT Tue Sep 18 2018
Areas affected...South-central...southeast and east-central SD
Concerning...Severe potential...Watch unlikely
Valid 180748Z - 181015Z
Probability of Watch Issuance...20 percent
SUMMARY...An ongoing cluster of elevated storms moving to the east
across south-central South Dakota is expected to have a greater
potential to produce a periodic threat for large hail, as it tracks
into southeast and east-central South Dakota during the next few
hours. If these storms are able to maintain their intensity, then
portions of far southwest Minnesota and adjacent northwest Iowa
could be affected, as well, toward 7 AM CDT.
DISCUSSION...IR imagery indicated cooling cloud tops again with the
ongoing eastward-moving SD cluster of storms, located in the
south-central part of this state at 0736Z. A progressive midlevel
impulse shifting east from western SD/NE combined with warm
advection at the apex of the western branch of the central Plains
southerly low-level jet has been supporting this somewhat
disorganized cluster, as it moved through weaker instability.
Although weak forcing aloft will be maintained as the impulse moves
east early this morning, this cluster will be advancing into the
eastern branch of the Great Plains low-level jet as it veers to
westerly by 12Z. This latter evolution in the low-level wind field
will eventually limit convergence into this cluster of storms,
suggesting a diminishing trend in coverage of stronger storms and
potential decrease in activity. Until this trend occurs, this
cluster of storms will begin to encounter stronger elevated
instability that is present across southeast SD into southwest MN
and northwest IA that should promote stronger updrafts in the short
term and larger hail at times.
..Peters/Edwards.. 09/18/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...FSD...ABR...UNR...
LAT...LON 43209889 43279946 43779986 44109981 44599938 44719857
44829745 44749614 44319569 43399571 43139599 42989676
43109825 43209889
from SPC Mesoscale Discussions http://bit.ly/2OAoH4c
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