Chris's Corner - Here Comes June

Eastern MO/west-central and southwest IL...
A Marginal severe risk has been introduced with this outlook
issuance for part of the middle Mississippi Valley region with the
greatest threats being for isolated damaging winds and hail. The
potential for isolated strong to damaging wind gusts will progress
to the south/southeast with the ongoing long-lived MCS, with the
leading extent having recently moved into northeast MO and
west-central IL per satellite/radar imagery and lightning data. The
associated convective outflow boundary extended from the leading
band of storms in west-central IL counties westward through northern
MO, while a confluence boundary extended from the MO Bootheel into
central MO. Observational data showed storms had also formed in
south-central MO in vicinity of this latter boundary, where the
environment has become very unstable with mixed-layer CAPE around
3000 J/kg. Although effective bulk shear is quite weak near this
confluence boundary, pulse-type storms could pose an isolated severe
risk. Otherwise, isolated damaging winds and hail will be possible
with the band of storms advancing to the south/southeast along and
either side of the Mississippi river this afternoon, with this
threat perhaps continuing into the early evening.