Mesoscale Discussion 1067
NWS Storm Prediction Center Norman OK
0258 AM CDT Sat Jun 17 2017
Areas affected...Eastern KS/western...central...and northeast
Concerning...Severe Thunderstorm Watch 341...343...344...
Valid 170758Z - 171000Z
The severe weather threat for Severe Thunderstorm Watch 341, 343,
SUMMARY...The greatest severe-weather threat (damaging winds and
hail) is expected to be across eastern KS and west-central to
southwest MO through early this morning. KS counties located along
the western part of WW 344 may need to be added, while parts of WW
341 is extended in time, as new storms continue to form across the
west/northwest periphery of the ongoing convective complex and
spread to the southeast.
Meanwhile, the severe-weather threat should continue to weaken
across WW 343.
DISCUSSION......WW 341 and WW 344...
Trends in IR satellite and radar imagery indicated the western and
southwest portions of the large KS/MO/IA/IL mesoscale-convective
complex across eastern KS and western and southwest portions of MO
should pose the greatest severe-weather threat through early this
morning. Coldest cloud tops and the most persistent, intense storms
per MRMS data extended from southeast Marshall/northern Pottawatomie
Counties KS to Franklin/northern Anderson and Miami Counties KS to
Henry/northwest Benton/southwest Pettis Counties MO. A southwest
40-kt low-level jet extending into the southwest portion of the MCC
from OK will sustain an inflow of very strong instability (2500-4000
J/kg of most-unstable CAPE per objective analyses and 06Z Lamont, OK
sounding). This combined with vertically veering wind profile (per
06Z LMN sounding), with effective bulk shear exceeding 45-50 kt,
will maintain strong updrafts. In addition to locally damaging
winds remaining possible, a plume of steep midlevel lapse rates (7-8
C/km per 06Z LMN sounding) extending from southern KS to southern MO
will favor a large-hail threat along the west/southwest part of the
MCC. This latter threat could result in additional counties in
east-central/southeast KS being added to WW 344.
Weakening trends in MRMS CAPPI (5-9 km) and MESH data combined with
a great reduction in lightning data across northeast MO suggest the
overall severe-weather threat should continue wane across WW 343
during the overnight. Veering 850-mb winds further weakening
low-level convergence across this region support this scenario, and
this watch could be canceled prior to 10Z (5 AM).
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 39719648 39549593 39309571 38929507 38759467 38639440
38639376 38679331 38529254 38439201 38579164 39519130
39059065 38609101 37839157 37099236 36739419 37019543