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Mesoscale Discussion 1364
NWS Storm Prediction Center Norman OK
0633 PM CDT Mon Jul 04 2022

Areas affected...Northeast IA...Southern WI...far northern IL...far
Southeast MN

Concerning...Severe potential...Watch possible 

Valid 042333Z - 050130Z

Probability of Watch Issuance...40 percent

SUMMARY...A severe risk may increase over the next hour or two
within a corridor across northeast Iowa and possibly far southeast
Minnesota into southern Wisconsin and possibly far northern
Illinois, although a more probable severe risk is expected later
this evening (after sunset) across parts of the region. The need for
a Watch is uncertain in the short term, but convective trends are
being closely monitored.

DISCUSSION...Recent visible satellite imagery reflects some
congestus/towering cumulus across northeast Iowa (near the Minnesota
border near/east of Mason City) into southwest Wisconsin. This
activity is occurring near/either side of a warm front, with
additional differential heating/outflow-related influences across
southern Wisconsin/northern Illinois per the earlier convection and
MCV. The atmosphere is very unstable particularly in vicinity of the
warm front, with upwards of 3000-4000 J/kg MLCAPE across
northeast/east-central Iowa into far southwest Wisconsin and
northwest Illinois.

Some key uncertainties remain regarding the extent/likelihood of
deeper convection in the short term across the region. This is
largely owing to post-MCV weak forcing for ascent influences along
with considerable mid-level warmth with westward-extent into and
across eastern/northern Iowa where 700 mb temperatures are 12-14C
(with eastward advection thereof). These factors cast some
uncertainty on the westward extent of the severe risk and short-term
overall likelihood of severe across the sub-regional area. Where
storms do develop, ample instability and strong deep-layer shear
(effective shear 40+ kt) could support supercells.

A somewhat higher certainty/probability severe risk is expected
after sunset especially across southern Wisconsin and potentially
far northern Illinois. Damaging winds and bouts of large hail with
any supercells would be the primary concerns, but a tornado risk may
also exist with surface-rooted storms (especially near the warm
front) given a further strengthening of low-level shear/SRH this
evening.

..Guyer.. 07/04/2022

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

ATTN...WFO...LOT...MKX...DVN...ARX...DMX...

LAT...LON   42779273 43579284 43739190 43879007 43448803 42818787
            42178813 42108953 42419164 42779273