485
ACUS01 KWNS 171241
SWODY1
SPC AC 171240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 AM CDT Mon Jun 17 2024

Valid 171300Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL PLAINS TO THE UPPER MIDWEST/UPPER GREAT LAKES...

...SUMMARY...
Scattered strong to severe storms are expected today mainly across
the Upper Mississippi Valley, and across the central High Plains and
Northern Plains late this afternoon through tonight, with damaging
winds and large hail possible.

...Upper Mississippi Valley/Upper Great Lakes...
A modestly organized quasi-linear band of convection continues to
make a general east-northeastward progression across southeast
Minnesota into west/northwest Wisconsin around sunrise. While the
convection has trended less organized and generally less intense,
strong/locally severe wind gusts have continued to occur within an
environment characterized by steep lapse rates and ample elevated
instability in vicinity of the synoptic front. Evolving MCV
influences and diurnal destabilization may allow strong/severe
storms to persist east-northeastward across central/northern
Wisconsin and perhaps Upper Michigan today, with additional
redevelopment a possibility this afternoon/early evening along the
outflow-reinforced front near the Iowa/Minnesota border vicinity.
Bouts of damaging winds and severe hail are the primary hazards.

...Northern/Central Plains...
A pronounced mid/upper-level trough over the Pacific Northwest will
shift east-northeastward over the northern Intermountain region
today and reach the northern High Plains tonight. Steady surface
cyclogenesis will occur today across interior Wyoming, and
subsequently into the central High Plains in vicinity of a
southwest/northeast-oriented front.

Near/south of the front, strong boundary-layer heating is expected
across the central High Plains of eastern Colorado into northwest
Kansas and southwest Nebraska. As temperatures warm into the lower
90s F, convective temperatures will be breached and isolated
supercells should develop, most probable near/east of the northeast
Colorado surface low and triple point vicinity including the
Colorado/Nebraska/Kansas border region. Forecast soundings exhibit
ample MLCAPE (2500-4000 J/kg) with steep lapse rates, along with
favorable shear for sustained rotating updrafts. Very large hail may
accompany this activity and some tornado threat may also exist.
These storms are likely to persist east-northeastward and
potentially cluster/organize to a degree toward central Nebraska
this evening.

Farther north, strong dynamic forcing will encourage convection to
develop across the High Plains of northeast Wyoming and southeast
Montana immediately ahead of the surging cold front. This activity
will spread northeast ahead of the shortwave trough into the Dakotas
during the overnight hours, further aided by a substantial increase
of a south-southwesterly low-level jet. The severe threat will shift
into the upper Red River Valley late tonight.

...Lower Great Lakes/Upper Ohio River Valley...
A convective cluster/MCV moving eastward out of southeast Lower
Michigan early this morning should broadly influence additional
thunderstorm development into the afternoon, within a moderately to
strongly unstable environment regionally. Deep layer shear will be
weak (generally 25 kt or less), but steepening low-level lapse rates
and a moist/unstable air mass could allow for some stronger
pulse-type storms capable of localized wind damage this afternoon.

..Guyer/Leitman.. 06/17/2024

$$