LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Wed Jun 28 2023
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE UPPER MISSISSIPPI VALLEY AREA...
...SUMMARY...
A relative concentration of severe risk may evolve across portions
of central and northwestern Wisconsin, and adjacent portions of
southeastern Minnesota and northeastern Iowa. A broader area of
isolated severe storm potential is evident across much of the
central/north-central portion of the country.
...Synopsis...
Upper-level troughing is forecast across the western and eastern
U.S. today, with these features flanking a flat ridge centered over
the south-central states. At the surface, weak features are
forecast to prevail, with the most pronounced feature being a
baroclinic zone/warm front extending westward across Kansas and then
northwestward across the central High Plains region during the
afternoon.
...Portions of Wisconsin, southeastern Minnesota, and far
northeastern Iowa...
Models forecast afternoon development of thunderstorms across the
southwestern Minnesota/western Wisconsin vicinity, within a zone of
warm advection ahead of a very weak surface low progged to be
crossing southern Minnesota during the afternoon. Given the belt of
enhanced mid-level westerlies, atop low-level southerly flow, shear
favorable for organized storms is expected. As such, a few stronger
storms will likely evolve with time, along with attendant risks for
severe-caliber wind/hail locally.
...Portions of the northern and central Plains into the Midwest...
Multiple small-scale disturbances will move westward across the
northern and central U.S., with an enhanced belt of flow between the
Canadian Prairie mid-level trough, and the central and southern
Plains ridge. As daytime heating results in widespread
destabilization from the central and northern High Plains eastward
to the Upper and Middle Mississippi Valley area, isolated
thunderstorms are expected to develop across a broad area.
A weak cold front crossing the Dakotas will likely be a focus for
development of isolated storms, a few of which could produce hail
and locally strong wind gusts during the afternoon and early
evening, before diminishing.
A few storms are also expected to develop within upslope flow across
southeastern Wyoming, and over the higher terrain of southeastern
Colorado/northeastern Oklahoma. Some potential for hail/wind would
exist with storms developing in either of these areas, with some
increase in storm coverage expected overnight as a southerly
low-level jet develops across the southern High Plains/western
Kansas. Some CAM runs suggest upscale growth into one or more
clusters, some of which sustain convection through the overnight
hours, shifting the storms as far east as the Mid Mississippi Valley
by the end of the period. However, these scenarios remain quite
uncertain, hence the broad, low-probability/MRGL risk area.
..Goss.. 06/28/2023
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