604
ACUS11 KWNS 041859
SWOMCD
SPC MCD 041858
WIZ000-IAZ000-MNZ000-042100-

Mesoscale Discussion 1534
NWS Storm Prediction Center Norman OK
0158 PM CDT Thu Jul 04 2024

Areas affected...central/northern Iowa...southern Minnesota

Concerning...Severe potential...Watch possible

Valid 041858Z - 042100Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorm activity may increase in coverage through the
afternoon and evening with potential for damaging winds and large
hail.

DISCUSSION...Thunderstorm activity has been ongoing near a cold
front moving eastward across Iowa and southern Minnesota. Surface
observations show a boundary lifting slowly across northern Iowa,
with additional cu developing and a few thunderstorms that have
initiated across eastern/northern Iowa into southern Minnesota.
Instability has been slow to increase and confined within a smaller
corridor across northwestern Iowa. Clearing south of the warm front
has led to an increase in heating and some airmass recovery, with
MLCAPE up to 1500 J/kg. Additional thunderstorm development will be
possible across the cold front and northward lifting boundary
through the afternoon. North of the warm front, supercells capable
of large hail will be possible, given deep layer shear around 30-45
kts near the IA/MN border.

As stronger mid-level flow overspreads central Iowa through the
afternoon, deep layer shear will increase across central/northern
Iowa. This may support development of a few supercells, with
potential for large hail and damaging wind should the thermodynamic
environment be able to further destabilize. Given lower confidence
in this scenario at this time, trends will be monitored for
potential watch issuance later this afternoon.

..Thornton/Gleason.. 07/04/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DVN...ARX...MPX...DMX...

LAT...LON   43179483 43769477 44419391 44409205 44039157 43729132
            43279117 42839120 42289224 42549476 43179483