MD 1249 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR NORTH CENTRAL IOWA AND SOUTHERN MINNESOTA
Mesoscale Discussion 1249
NWS Storm Prediction Center Norman OK
0937 PM CDT Sat Jun 24 2023
Areas affected...north central Iowa and southern Minnesota
Concerning...Severe potential...Watch possible
Valid 250237Z - 250400Z
Probability of Watch Issuance...40 percent
SUMMARY...New convective development ahead of the ejecting shortwave
may continue to intensify tonight. Isolated hail and damaging winds
are possible. While uncertain, there is potential a weather watch
may be needed.
DISCUSSION...Across portions of the upper Midwest, evening WV
imagery showed a compact upper low ejecting eastward into portions
of northern IA and southern MN. Ahead of the upper low, broad scale
ascent from mid-level height falls and DPVA has increased, resulting
in new storm development over the past hour. Despite the loss of
diurnal heating, area RAP soundings remain moderately unstable with
steepening mid-level lapse rates from cold advection aloft.
Deep-layer shear remains favorable for supercells with area VADs
showing 45-50 kt of effective shear atop the moderate MUCAPE. There
appears to be a few hour window for storms to mature and pose a risk
for isolated large hail and damaging wind gusts across portions of
northern IA and southern MN tonight. Confidence in storm and severe
coverage, especially the eastward extent in the wake of previous
outflow, is not overly high. However, recent HRRR runs do show some
intensification of ongoing storms is possible. Given the potential
for large hail and damaging winds, conditions are being monitored
for possible Severe Thunderstorm Watch issuance.
..Lyons/Bunting.. 06/25/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ARX...MPX...DMX...FSD...
LAT...LON 42189542 42219561 42329593 42619624 43169636 43899577
44789476 44999391 44859348 44319298 43709268 43109263
42769272 42369283 42219320 42199323 42189542
