MD 0457 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR NORTHEAST IOWA…FAR SOUTHEAST MINNESOTA…AND SOUTHWEST/CENTRAL WISCONSIN
Mesoscale Discussion 0457
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue Apr 04 2023
Areas affected...northeast Iowa...far southeast Minnesota...and
southwest/central Wisconsin
Concerning...Severe potential...Watch likely
Valid 041954Z - 042230Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms are expected to develop in the
22-00z/5pm-7pm CDT time frame. Large hail, damaging gusts and a
couple tornadoes appear likely through this evening. A watch will
likely be needed in the next couple of hours.
DISCUSSION...Some uncertainty remains regarding how far north the
surface warm front will advance across the region through this
evening. Most guidance suggest the boundary will lift into far
southern WI by this evening. Thunderstorms are expected to develop
in the vicinity of the surface low across western/central IA in the
next couple hours. Storms will track northeast near, or to the cool
side, of the northward-advancing warm front. This will likely result
in most convection remaining elevated, though a couple of storms
could become rooted in the frontal zone across northeast IA or far
southwest WI. The storms that can ingest better quality low-level
moisture and vorticity along the boundary will have a better
opportunity to produce a tornado. However, current thinking is that
convection will largely remain elevated. Nevertheless, strong
vertical shear will support supercells. Very steep midlevel lapse
rates will support MUCAPE around 500-1500 J/kg and large hail will
be possible. Fast moving storms, coupled with strong deep-layer flow
also will support some damaging wind potential.
A relative max in severe potential will exist across southern
portions of the MCD where at least some chance of near surface-based
convection will exist within the warm frontal zone. With northward
extent, overall potential will gradually lessen. A watch will likely
be needed in the next couple of hours.
..Leitman/Hart.. 04/04/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...LOT...MKX...DVN...ARX...MPX...DMX...
LAT...LON 42419421 42639424 42909410 43609329 44059229 44159170
44359055 44278942 44168904 43898880 43638873 43048877
42538916 42438961 42499184 42419421
