Subj : DAY1SVR: Marginal Risk
To   : All
From : Mike Powell
Date : Fri Oct 13 2023 09:12:00

ACUS01 KWNS 130542
SWODY1
SPC AC 130540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Fri Oct 13 2023

Valid 131200Z - 141200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
IOWA...NORTHERN MISSOURI...AND NORTHWEST ILLINOIS...

....SUMMARY...
A few severe storms will be possible this afternoon over parts of
Iowa, northern Missouri, and northwest Illinois.

....Synopsis...
An upper low will fill as it moves from NE into IA through 00Z, and
toward southern Lake MI by 12Z Saturday. Moderate cyclonic flow
aloft will remain south of the upper low, providing shear and
cooling aloft over much of the lower MO Valley and toward the OH
Valley.

At the surface, low pressure will move east across IA during the
day, and into IL and IN overnight. Mid to upper 50s F dewpoints will
be common south of the low, and east of a cold front surging across
MO and across the Ozarks late in the day. Dewpoints may increase
further into the lower 60s F after 00Z as a warm front lifts north
across IL and IN. While moderate to strong shear will exist with
this upper trough and near the surface low, the severe threat will
be mitigated greatly by lack of appreciable instability.

Elsewhere, mid 70s F dewpoints will remain over much of the FL
Peninsula with a temporary ridge aloft, but drying will occur over
northern parts of the state in closer proximity to surface high
pressure.

....IA...MO...IL...
Elevated thunderstorms will be possible early in the day within a
warm conveyor stretching from the Ozarks into WI, with MUCAPE of a
few hundred J/kg. Behind this activity, a warm sector will develop
from MO into IA ahead of the approaching surface low. Surface
heating combined with cooling aloft will likely result in up to 500
J/kg MLCAPE, centered over IA.

The greatest severe threat appears to be from 20-02Z near the
surface low and arcing southeastward along the cold front, from IA
into northern MO, where low-level convergence will be maximized.
Cool temperatures aloft and expected cellular storm mode may favor
hail to 1.00" diameter, and low-level SRH near the low and warm
front could briefly support a supercell or two with brief tornado
threat before winds veer and the warm-sector quality diminishes.
Otherwise, additional elevated thunderstorms are forecast to spreads
east overnight as far east as OH, supported by weak destabilization.

...Jewell.. 10/13/2023

$$
--- SBBSecho 3.14-Linux
 * Origin: Ilink: CCO - capitolcityonline.net (454:1/105)

.