MD 1622 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PARTS OF NORTHERN AND CENTRAL IA
Mesoscale Discussion 1622
NWS Storm Prediction Center Norman OK
0846 PM CDT Sun Jul 31 2022
Areas affected...Parts of northern and central IA
Concerning...Severe potential...Watch unlikely
Valid 010146Z - 010345Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated large hail and locally severe gusts are possible
if convection can develop/persist over parts of northern and central
IA tonight. A watch is not currently expected.
DISCUSSION...Latest IR satellite imagery shows cooling cloud tops
along a surface wind shift accompanying a southwestward-arching cold
front across northern IA, where isolated convective development is
underway. Subtle large-scale ascent along the nose of an approaching
midlevel jet streak and a plume of low-level warm advection ahead of
the surface front could support some increase in convective
development over the next couple hours -- aided by lower 70s
dewpoints beneath a plume of modest midlevel lapse rates.
If convection can develop and persist over northern into central IA
prior to a substantial increase in nocturnal boundary-layer
stability, 30-40 kt effective shear oriented perpendicular to the
surface wind shift and a low-level veering wind profile could
conditionally support a few semi-discrete, loosely organized
clusters capable of isolated large hail and locally severe gusts.
Current thinking is that any surface-based severe risk would be too
isolated/brief for a watch consideration, though convective trends
will be monitored.
..Weinman/Hart.. 08/01/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DVN...ARX...DMX...
LAT...LON 41549410 41849468 42359468 42789424 43389365 43479328
43499257 43379204 43089183 42339209 41609311 41549410
