640
ACUS11 KWNS 211815
SWOMCD
SPC MCD 211815
WIZ000-211945-

Mesoscale Discussion 0873
NWS Storm Prediction Center Norman OK
0115 PM CDT Tue May 21 2024

Areas affected...Southern WI

Concerning...Severe potential...Watch possible

Valid 211815Z - 211945Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated hail and/or damaging gusts are possible. Limited
severe coverage will likely preclude the need for a watch in the
short term. A greater severe risk is anticipated later this evening
as the line of storms moving out of IA moves into the region.

DISCUSSION...Surface observations reveal a warm front extends
east-to-west across far southern WI, with temperatures in the upper
70s/low 80s south of the boundary and in the mid 60s to low 70s
north of it. Dewpoints south of the boundary are in the upper 60s
while remaining in the low to mid 60s north of it. Ongoing
convective cluster moving across southwest WI has recently shown a
strengthening trend, likely a result of increased warm-air advection
across the warm front. Given the persistence of the strong low-level
flow and increasing low-level moisture, this cluster is forecast to
continue quickly northeastward, with some potential for isolated
hail and/or damaging gusts as it does.

A more isolated storm has developed east of this cluster in Dane
County. This storm is very close to the warm front but still looks
to be slightly elevated, although the more recent slow, more
eastward storm motion may be indicating a trend toward more
surface-based character. Recent MKX VAD sampled enough low-level
curvature to support some tornado potential if the storm can become
surface-based. Otherwise, the primary risk with this storm is large
hail.

Limited severe coverage will likely preclude the need for a watch,
but convective trends are being monitored closely. A greater severe
risk is anticipated later this evening as the line of storms moving
out of IA moves into the region.

..Mosier/Guyer.. 05/21/2024

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

ATTN...WFO...GRB...MKX...ARX...

LAT...LON   42718888 42989012 44149022 44618904 44148788 43108817
            42718888