####018002974####
ACUS01 KWNS 160539

SWODY1

SPC AC 160538



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

1238 AM CDT Tue Apr 16 2024



Valid 161200Z - 171200Z



...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS

OF THE MIDWEST...



...SUMMARY...

Scattered severe thunderstorms are likely today, centered mostly

over the midwestern states of northern Missouri/Iowa/northwestern

Illinois. Hail, wind, and tornadoes are expected in this corridor.

More isolated activity could develop as far south as the Ozarks of

northern Arkansas.



...Midwest...



Upper low is currently located over southeast CO, and will soon

begin ejecting northeast in line with latest model guidance into the

central Plains. By 18z this feature should advance into eastern NE

as 90kt 500mb speed max translates through the base of the trough,

across northern OK, into northwestern MO. In response to this

dynamic system, strong LLJ will focus across the eastern Plains

early then shift into the mid/upper MS Valley by 18z.



Low-level warm advection is expected to prove instrumental in

early-day convection, in association with the LLJ. This activity

should be ongoing at the start of the period, focused over the

mid-MO Valley. Subsequent movement/development is expected

downstream across IA/southern MN as the warm conveyor shifts east.

While strong shear will support this convection, the primary concern

will be with secondary development in association with a pronounced

mid-level dry slot. Latest model guidance suggests surface-3km lapse

rates will steepen to near 9 C/km across southeast NE/northeast KS

by 18z. Leading edge of this steeper lapse-rate plume will advance

across western IA, immediately ahead of the surface low. As a

result, boundary-layer heating will contribute to substantial

buoyancy and some areas may experience MLCAPE near 2000 J/kg. 

Surface-based parcels are forecast to be uninhibited by 17-18z

across western IA. Current thinking is scattered convection should

develop within this zone of destabilization then spread northeast.

Surface warm front is expected to serve as a northern limit to

surface-based convection, along with any appreciable tornado risk.

Large hail can be expected with supercells, and favorable shear will

support the potential for tornadoes, a few potentially strong. This

activity will spread across IA/extreme northern MO into northwestern

IL during the evening.



Farther south into the Ozarks, severe threat is much more

conditional. Forecast soundings exhibit poor lapse rates and at

least weak inhibition through much of the period. It's not real

clear how robust updrafts will be, despite the strong shear, given

the marginal lapse-rate environment. Will maintain SLGT Risk into

this portion of the lower MS Valley but convection may struggle much

of the period.



..Darrow/Lyons.. 04/16/2024



$$