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ACUS01 KWNS 291233

SWODY1

SPC AC 291232



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0732 AM CDT Fri Mar 29 2024



Valid 291300Z - 301200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF

THE MIDWEST TONIGHT...



...SUMMARY...

Marginally severe hail is possible over portions of the Midwest

tonight.



...Synopsis...

The mid/upper-level pattern will feature strong, progressive troughs

-- each with an accompanying synoptic-scale cyclone -- near the East

and West Coasts, and low-amplitude, large-scale ridging in between. 

The western low -- quite prominent in moisture-channel imagery now

west of Cape Mendocino -- should move southeastward and stay

offshore from CA through the period.  However, downstream  southwest

flow and several embedded vorticity lobes/shortwaves will move over

the Intermountain West.  Portions of the central and northern

Rockies, as well as the Pacific Coast, should reside beneath enough

midlevel cooling/instability and low/middle-level moisture to

support isolated thunderstorms.  Downstream, a leading shortwave

trough is evident from southern SK across eastern MT to central WY. 

This feature should move eastward across the northern Plains today,

reaching the eastern Dakotas by 00Z, and crossing the upper

Mississippi Valley around 12Z tomorrow.



At the surface, 11Z analysis showed a frontal-wave low near HLC,

with short cold front southwestward over western KS, and warm front

across northern MO, south-central IL, to near CVG, and northern WV. 

Another low was apparent over southeastern SK, with a trough

connecting these lows across the western Dakotas and central NE. 

By 00Z, the southern low should reach southwestern/central IA, with

cold front southwestward over southwestern KS, and warm front across

central IL to southern IN.  A trough -- with some reinforcement

related to the mid/upper perturbation -- still should extend from

that low to the northern one, by then near the southern SK/MB line. 

By 12Z, the southern low should approach the southwestern shore of

Lake Michigan (near the IL/WI line), with cold front to northern MO,

northern OK and the TX Panhandle.  The warm front should extend from

the low across southwestern Lower MI to western/southern OH.



...Midwest...

During the day, the central Plains to Midwest should remain capped

for substantial, surface-based convection, the result of a

combination of advection of EML air aloft from higher terrain in the

West, with insufficient moisture and lift.  However, with continued

moist/warm advection in the increasing LLJ, and the approach of

large-scale DCVA/lift aloft related to the mid/upper trough,

convective potential will increase this evening north of the warm

front over parts of IA/IL.  Isentropic lift to LFC will occur as

parcels saturate in the 700-850-mb layer and MUCINH erodes rather

quickly.  Resulting elevated thunderstorms should shift eastward

into southern WI and central/northern IL, then late overnight, the

Michiana/northwest OH area.  



Greatest inflow-layer buoyancy and hail potential should be with

relatively discrete cells in the early stage of the convective

process across IA/IL, then mainly the southern part of the

thunderstorm area as it crosses IL.  Expect MUCAPE of around 500-700

J/kg developing from southern IA to central IL, decreasing to under

300 J/kg over much of southern WI.  In forecast soundings,

effective-shear magnitudes vary a lot with CAPE depth, but generally

should be in a 30-40 kt range to support some thunderstorm

organization.  Locally strong gusts cannot be ruled out either,

given a relatively dry subcloud layer present in forecast soundings,

and potential for downdraft winds to penetrate a relatively shallow,

near-surface stable layer.  However, severe-gust potential still

appears too uncertain and unfocused for a wind area to be added at

this time.



..Edwards/Leitman.. 03/29/2024



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