Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Fri Mar 29 2024
Valid 291630Z - 301200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT FROM
EASTERN IA INTO NORTHERN IL...
...SUMMARY...
Marginally severe hail is possible tonight from eastern Iowa into
northern Illinois.
...Synopsis...
A deep midlevel low over the eastern Pacific will approach the
central CA coast tonight, as an associated baroclinic zone spreads
slowly eastward/inland this afternoon/evening. Weak buoyancy within
the baroclinic zone could support some embedded convection with
isolated lightning flashes. A downstream speed max over CO this
morning will move toward the mid MS Valley overnight, and will help
maintain lee cyclogenesis today across western KS and a weak/mobile
cyclone into IA/IL tonight.
...Eastern IA/northern IL tonight...
A modifying Gulf of Mexico air mass is returning northward into the
southern Plains, to the east of the lee cyclone in western KS. Some
increase in low-level moisture in a zone of low-level warm
advection, beneath midlevel lapse rates near 7.5 C/km, will support
elevated thunderstorm development early tonight over eastern IA and
storms will subsequently spread eastward over northern IL
(immediately in advance of the weak surface cyclone and ejecting
midlevel speed max). MUCAPE near 1000 J/kg, relatively cool
midlevel temperatures (near -18 C at 500 mb) and modest hodograph
length/curvature may support some low-end/elevated supercells
capable of producing isolated large hail of 1-1.5 inches in diameter
before storm coverage increases and storm intensity decreases late
tonight.
..Thompson/Wendt.. 03/29/2024
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