LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 AM CDT Tue Jul 04 2023
Valid 041300Z - 051200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
OF NORTHERN KANSAS AND SOUTHERN NEBRASKA...
...SUMMARY...
Severe thunderstorms are most likely today from the central Great
Plains into the western Great Lakes from late afternoon into
tonight. Severe thunderstorm gusts, possibly significant, will be
the primary hazard, with instances of large to very large hail also
possible.
...Central Plains to upper Midwest...
Thunderstorms associated with a decaying MCS will continue to move
east across eastern SD/southwest MN this morning. Although cloud
cover may delay diurnal heating in some areas early, eventual
destabilization is expected by this afternoon across the upper
Midwest/western Great Lakes region.
As a positively-tilted mid-level trough moves east over the
central/northern Plains today, a cold front will move east/southeast
from the upper Midwest southwest into the central High Plains.
Strong insolation of a moist air mass south of the front and
seasonably steep mid-level lapse rates over the plains portion of
the risk area will result in moderate-strong surface-based
instability this afternoon in advance of the front.
Isolated thunderstorms are expected to develop mid/late afternoon
initially over the higher terrain of northern CO/southeast WY, with
additional development along the front from eastern SD/southwest MN
where more substantial large-scale ascent with the upper trough will
be present. With time, thunderstorm coverage should increase along
the front aided by frontal convergence and a reduction in CINH.
Initial development will consist of both supercell and multicell
storm structures as 30-40 kts of deep-layer shear will be present
over much of the risk area. A significant hail area has been
introduced over central NE where steep mid-level lapse rates and
potential for initially more isolated storm development appears
greatest. South of the front, a well-mixed boundary layer/very steep
low-level lapse rates should result in storms evolving into
clusters/line segments with damaging winds as the primary severe
hazard. Modestly increasing warm advection tonight with
strengthening low-level jets across northern WI/Lake Superior and
also across western KS should allow the severe risk to continue into
the early overnight hours.
...Mid-Atlantic and southeast...
Pockets of moderate/strong MLCAPE are expected by afternoon along a
diffuse surface boundary from the coastal mid-Atlantic region west
to northeast TX, with scattered thunderstorms developing within a
moist (PW in excess of 1.75 to 2 inches) and weakly sheared air
mass. Isolated stronger updrafts or storm clusters may have the
potential for strong/locally damaging gusts.
..Bunting/Gleason.. 07/04/2023
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