020
ACUS11 KWNS 161733
SWOMCD
SPC MCD 161733
ILZ000-IAZ000-161930-

Mesoscale Discussion 1289
NWS Storm Prediction Center Norman OK
1233 PM CDT Sun Jun 16 2024

Areas affected...parts of southeastern Iowa and northwestern
Illinois

Concerning...Severe potential...Watch possible

Valid 161733Z - 161930Z

Probability of Watch Issuance...60 percent

SUMMARY...A cluster of intensifying thunderstorms may pose a risk
for small to marginally severe hail, before gradually organizing and
posing increasing potential to produce strong to severe wind gusts
through 2-4 PM CDT.  A severe weather watch will probably be needed
at some point this afternoon, though it remains a bit uncertain how
soon.

DISCUSSION...Renewed thunderstorm development is underway near the
center of a convectively generated or enhanced mid-level cyclonic
vorticity center now approaching the Mississippi River vicinity
between Burlington and Moline.  This perturbation is embedded within
the southern portion of weak mid-level troughing which has emerged
from the Great Plains and is forecast to continue shifting
into/across the upper Great Lakes through late afternoon, while
mid-level heights otherwise tend to rise.

While deeper-layer shear is weak, an enhanced belt of
lower/mid-troposperic flow (40+ kt centered around 700 mb) may
contribute to shear profiles conducive to an upscale growing and
organizing cluster of storms.  This will include a configuration
allowing for easterly high-level system relative flow advecting
anvil cloud cover and precipitation upstream (to the west), and not
impeding destabilization within modest easterly near-surface updraft
inflow.

Mid-level inhibition for parcels within a gradually moistening
boundary layer (including surface dew points now around or above
70F) across northwestern Illinois is becoming increasingly
negligible with continuing insolation, and CAPE is increasing in
excess of 2000 J/kg.  As the updraft inflow of ongoing convection
continues to become increasingly unstable, substantive further
intensification and upscale growth seems probable during the next
few hours.  It is possible that this could be accompanied a risk for
marginally severe hail, before latent cooling in downdrafts
gradually contributes to a strengthening northeastward and eastward
propagating cold pool with increasing potential to produce strong to
severe surface gusts.

..Kerr/Gleason.. 06/16/2024

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

ATTN...WFO...LOT...ILX...DVN...

LAT...LON   40429054 40489126 40849117 41029117 41349134 41689065
            42068990 42078913 41598873 41128889 40678959 40429054