MD 0342 CONCERNING SEVERE THUNDERSTORM WATCH 72… FOR NORTHEAST KS TO CENTRAL IA
Mesoscale Discussion 0342
NWS Storm Prediction Center Norman OK
0558 PM CDT Thu May 03 2018
Areas affected...Northeast KS to central IA
Concerning...Severe Thunderstorm Watch 72...
Valid 032258Z - 040030Z
The severe weather threat for Severe Thunderstorm Watch 72
continues.
SUMMARY...Severe-weather threat spreading north into more of
southern and central Iowa this evening has resulted in a north and
northeast expansion of WW 72. Severe storms remain possible across
much of WW 72, though some diminishing trend in coverage of
strong-severe storms may persist in northeast KS.
DISCUSSION...Trends in surface observations since late afternoon
showed a warm front was advancing north, with the 22Z position
analyzed from near and just north of I-80 in western and central IA,
and then extended northeast into southwest WI. Southerly low-level
winds in the warm sector have allowed greater moisture to advance
into central and northeast IA with surface dewpoints in the middle
60s. Despite earlier surface heating and this moisture return,
modest midlevel lapse rates of 6.5-7 C/km are limiting stronger
destabilization with mixed-layer CAPE up to 1000 J/kg. Given strong
effective bulk shear and effective SRH of 200-300 m2/s2, organized
storms with low-level rotation will remain possible. Enhance
low-level shear in vicinity of the warm front, given backed winds,
could increase the tornado threat. Otherwise, large hail and
strong/damaging wind gusts will be possible as well.
Farther southwest, weaker midlevel lapse rates as compared to the
modest values in IA may be inhibiting stronger/sustained updrafts
across this portion of WW 72. In addition, veered low-level winds
southwest of the southwestern IA surface low are limiting
convergence and likelihood for greater storm coverage.
..Peters.. 05/03/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DMX...EAX...OAX...TOP...ICT...
LAT...LON 38649695 39429707 41039621 41419530 41829488 41909271
41169292 40669314 40579417 40059424 40039457 39549459
39509499 39299518 39069516 39049550 38909551 38859597
38509653 38539686 38649695
from SPC Mesoscale Discussions http://bit.ly/2wja2G7
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