183
ACUS01 KWNS 190531
SWODY1
SPC AC 190529

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 AM CDT Thu Sep 19 2024

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
MINNESOTA...IOWA AND WESTERN WISCONSIN SOUTHWARD INTO EASTERN KANSAS
AND WESTERN MISSOURI...

...SUMMARY...
Scattered severe thunderstorms are possible across central/eastern
Minnesota, Iowa, and western Wisconsin. A couple tornadoes, isolated
large hail, and damaging winds may occur. An area of locally severe
gusts and hail may also develop over parts of eastern Kansas,
southwest Missouri, and into northeast Oklahoma.

...Synopsis...
A negatively tilted shortwave trough will move across the Dakotas
and MN during the day, with veering midlevel winds into western MN
by late afternoon. Farther south, moderate west/southwest winds in
the midlevels will extend into NE and IA, with weaker west to
northwest winds around a southern Plains upper high from KS/OK into
MO and AR. In the high levels, flow will be strongest across the
central Plains, with weakening winds over the northern Plains/upper
MS Valley.

At the surface, the primary low will move into southern MB, with a
cold front moving into MN and western IA by mid afternoon. A wind
shift/surface trough will also extend southward across eastern KS
and into northern OK at that time.

Southerly surface winds will set up a plume of mid to upper 60s F
dewpoints east of the front/surface trough, and this will aid
moderate destabilization across the length of the front, with
scattered severe storms from MN to perhaps OK.

...Upper MS Valley...
Scattered early day elevated storms are likely to dissipate by
midday as they move out of MN/IA into WI, with destabilization in
their wake. Strong heating near the surface trough/front along with
cool temperatures aloft will yield MUCAPE to around 3000 J/kg,
beneath 35-40 kt 500 mb winds. A broken line of storms including
supercells are expected after 21Z over much of central and eastern
MN and into IA. A couple tornadoes are most likely from IA into
southern MN and southwest WI where effective SRH may exceed 200
m2/s2. Given the northward lifting of the shortwave trough, and
increasing inhibition east of the MS River, the primary threat are
may remain relatively narrow.

...Eastern KS into western MO and into OK...
A few thunderstorms may be ongoing early this morning from IA into
northwest MO, near the 850 mb theta-e plume and beneath subtle
height falls. A cell or two may persist into the afternoon, likely
translating southeastward across western MO. A greater risk of
locally severe wind gusts or hail will then develop near and just
west of the early day activity, as a plume of steep lapse rates
develops out of OK into KS. While midlevel subsidence may limit
instability somewhat, plenty of CAPE will be present at or above
2000 J/kg, with a lengthy mid to upper level hodograph by virtue of
northwest flow aloft. As such, hail may still occur with the
cellular storm modes, and favorable time of day and hot surface
conditions will favor locally strong to damaging gusts.

..Jewell/Weinman.. 09/19/2024

$$