MD 0786 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR IOWA INTO FAR NORTHEAST MISSOURI
Mesoscale Discussion 0786
NWS Storm Prediction Center Norman OK
1201 PM CDT Sat May 13 2023
Areas affected...Iowa into far northeast Missouri
Concerning...Severe potential...Watch likely
Valid 131701Z - 131900Z
Probability of Watch Issuance...80 percent
SUMMARY...T-storm coverage and intensity is expected during the
18-20 UTC period across Iowa into far northeast Missouri. These
storms will likely pose a risk for large hail, severe winds, and a
few tornadoes. A watch will likely be needed to address this
concern.
DISCUSSION...Latest surface observations depict a warm front draped
from northeast IA southeastward into far northeast MO. On the cool
side of this boundary, eroding cloud cover has allowed for
temperatures to begin warming into the low to mid 70s with further
heating/destabilization expected through mid afternoon as clouds
continue to slowly clear amid weak subsidence noted in low-level
water-vapor imagery. Modified observed and forecast soundings across
central to eastern IA suggest that while buoyancy profiles remain
somewhat modest, the low-level warming is eroding mixed-layer
inhibition. Initial convective initiation along the warm front,
where mesoscale lift and diurnal warming is greatest, has been noted
south of Des Moines over the past 20 minutes, lending credence to
recent CAM solutions that hint at more widespread convective
initiation within the next 2-3 hours.
As thunderstorms develop, storm motions and deep-layer shear vectors
orthogonal to the warm front should support initially discrete storm
modes. VWP observations from KDMX (to the north of the front where
low-level flow is backed to the southeast) show sufficient low-level
curvature for around 100-150 m2/s2 0-1 km SRH. Forecast soundings
hint that strong shear in the 1-6 km layer will favor elongated
hodographs favorable for splitting supercells. Consequently,
organized convection appears likely with an attendant large hail,
severe wind, and tornado threat. The quality of destabilization (and
subsequently the severe threat) becomes less certain with
east/northeast extent; however, a watch will likely be needed to
address the developing severe threat.
..Moore/Mosier.. 05/13/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LSX...DVN...ARX...MPX...DMX...EAX...FSD...OAX...
LAT...LON 41009087 40519106 40079137 39849204 39819267 40009300
40419344 40909397 41439457 41969533 42359590 42589642
42809651 43239639 43549609 43729567 43789530 43669446
42449215 41519101 41009087
