MD 0791 CONCERNING TORNADO WATCH 223… FOR PARTS IOWA
Mesoscale Discussion 0791
NWS Storm Prediction Center Norman OK
0624 PM CDT Sat May 13 2023
Areas affected...Parts Iowa
Concerning...Tornado Watch 223...
Valid 132324Z - 140030Z
The severe weather threat for Tornado Watch 223 continues.
SUMMARY...The severe risk is gradually diminishing across Tornado
Watch 223, though an additional tornado or two is possible across
parts of south-central and perhaps northwest IA during the next hour
or so.
DISCUSSION...Over south-central IA, earlier diurnal heating of a
moist boundary layer (lower 70s surface dewpoints) has yielded a
small pocket of favorable surface-based instability -- where MLCAPE
is slightly higher (around 1000 J/kg). This surface-based inflow,
combined with backed surface winds beneath weakly veering flow aloft
(around 130 m2/s2 0-1km SRH per DMX VWP), could support an
additional brief supercell tornado or two during the next hour or
so. Farther north in northwest IA, enhanced background vorticity
amid ongoing shallow supercell structures could also support an
additional brief tornado or two before nocturnal static stability
increases.
..Weinman.. 05/13/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...DMX...
LAT...LON 40909293 41009333 41329350 41609344 41739327 41709292
41369247 41069229 40899241 40909293
