ACUS02 KWNS 120601
SWODY2
SPC AC 120559

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Wed Jun 12 2024

Valid 131200Z - 141200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...LOWER MISSOURI VALLEY...MID MISSISSIPPI VALLEY
AND SOUTHERN GREAT LAKES...

...SUMMARY...
Thunderstorms associated with large hail and severe gusts will be
possible on Thursday in parts of the central Plains, lower Missouri
Valley, mid Mississippi Valley and southern Great Lakes. Marginally
severe storms will also be possible in parts of the central High
Plains.

...Central Plains/Lower Missouri and Mid Mississippi
Valleys/Southern Great Lakes...
An upper-level trough will move eastward into the western Great
Lakes region on Thursday, as an associated 70 to 90 knot mid-level
jet translates eastward across the upper Mississippi Valley. At the
surface, a cold front is forecast to move southward across Nebraska,
Iowa and northern Illinois. South of the front, surface dewpoints in
the upper 60s to the mid 70s F will likely result in moderate
instability by afternoon. Although a cap is forecast to be in place
during the day, it should weaken by early evening to allow for
convective initiation. As low-level convergence increases near the
front, thunderstorms are expected to develop and move southeastward
across the lower Missouri and mid Mississippi Valleys.

Model forecasts suggest that the strongest instability early
Thursday evening will be in northeast Kansas and northern Missouri.
In this area, NAM forecast soundings at 03Z/Friday have MLCAPE
approaching 5000 J/kg, with 0-6 km around 40 knots and 700-500 mb
lapse rates between 7 and 7.5 C/km. This would be favorable for
supercell development. Although large hail would be possible with
the strongest of storms, the warm air aloft may temper the hail
threat somewhat. Northwest mid-level flow could also favor linear
development. Short line segments that can become organized could
have a wind-damage threat. The strong instability could enable the
severe threat to continue into the late evening, or even into the
overnight period.

Further northeast into the southern Great Lakes, a narrow corridor
of moderate instability will likely be in place ahead of the front
in the afternoon. Thunderstorms are expected to form along the
front, and move southeastward across Lower Michigan and northern
Indiana. A couple persistent clusters will be possible from late
afternoon into the mid evening. NAM Forecast soundings in southern
Lower Michigan during the early evening have MLCAPE around 2000 J/kg
with 0-6 km shear near 50 knots. This will likely support supercell
development, with a potential for large hail. An isolated tornado
threat may also develop with the strongest of supercells. A
potential for severe line segments with damaging wind gusts will
also exist.

...Central High Plains...
An upper-level ridge will move through the Rockies on Thursday, as
west-northwest mid-level flow remains over the central High Plains.
An axis of moderate instability is forecast to be in place by
afternoon from far northeast Colorado into far northern Kansas.
Isolated thunderstorms are expected to form along and near the
instability axis during the late afternoon. Although lapse rates
will be very steep, warm air aloft and limited large-scale ascent
will likely keep any severe threat marginal.

..Broyles.. 06/12/2024

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