Mesoscale Discussion 1721

Issued

Jul 28, 2024, 3:49 PM CDT (20:49 UTC)

Expired

Jul 28, 2024, 5:45 PM CDT

In force

116 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Des Moines radar (KDMX), 116 km from the middle of the area, began a volume at 20:52 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

280 
ACUS11 KWNS 282050
SWOMCD
SPC MCD 282049 
IAZ000-NEZ000-SDZ000-282245-

Mesoscale Discussion 1721
NWS Storm Prediction Center Norman OK
0349 PM CDT Sun Jul 28 2024

Areas affected...Northwest to central Iowa

Concerning...Severe potential...Watch possible 

Valid 282049Z - 282245Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms associated with an MCV across the mid
Missouri River Valley have shown some signs of intensification over
the past half hour. Trends will continue to be monitored for the
need for a watch at some point this afternoon/evening.

DISCUSSION...Convection has been ongoing for much of the day across
eastern NE as a residual MCV meanders across the mid-MO River
Valley. Much of this activity has been driven by a combination of
ascent associated with the MCV as well as modest warm air advection
between 850-700 mb. Regional VWPs across eastern KS have shown some
strengthening of the low-level flow within this warm advection
regime, suggesting that lift is gradually increasing. Concurrently,
daytime heating through broken cloud cover has allowed for
temperatures to climb into the upper 80s across eastern NE into IA
with a corresponding reduction in surface-based inhibition.
Consequently, convection has shown some signs of intensification
over the past 30 minutes, including weak mid-level rotation and
periodic lightning jumps with the deeper, more intense updrafts. 

Given moderate SBCAPE and sufficient deep-layer shear, organized
convection appears possible, but storm mode remains uncertain. More
discrete cells developing on the southern periphery of the MCV
(where warm advection ascent should be strongest) may pose a large
hail threat before storm interactions promote gradual upscale growth
- possibly into an organized cluster later this evening. More recent
GOES one-minute imagery shows that the more intense updraft pulses
remain somewhat short lived, possibly indicating that stronger
forcing for ascent (in the form of an even stronger low-level jet
this evening) will be required to fully realize the convective
environment. Trends will continue to be monitored, and watch
issuance is possible at some point later this afternoon/evening.

..Moore/Gleason.. 07/28/2024

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

ATTN...WFO...DMX...FSD...OAX...

LAT...LON   41639587 42319667 42609677 42789667 42929599 42929480
            42889434 42729407 42509387 42299371 42119369 41829376
            41629392 41459429 41439491 41489531 41589575 41639587

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.