LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Wed Aug 23 2023
Valid 231300Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT
LAKES...
...SUMMARY...
Thunderstorms associated with damaging wind gusts and hail are
expected tonight across parts of the lower Great Lakes and upper
Ohio Valley. Isolated large hail and/or severe wind gusts may also
occur across parts of the northern Plains late this afternoon and
evening.
...Great Lakes/Upper Ohio Valley...
Initially, isolated large hail potential exists early today with
elevated storms ongoing mostly across northern/eastern Michigan.
These storms are focused near the terminus of a moderately strong
low-level jet, to the north of the prominent anticyclone centered
over the Lower Missouri Valley/Ozarks. Any such isolated severe
potential is expected to wane into late morning/midday as the
low-level jet weakens.
A moist/very unstable air mass is otherwise expected to quickly
advect east-northeastward across the region today in tandem with a
warm front, with surface dewpoints in the low/mid 70s F becoming
more prominent into sizable portions of Lower Michigan and Ohio.
Storms are expected to develop, perhaps as early as near/just after
sunset, especially near a weak surface wave/triple point and warm
front vicinity, and become more prominent regionally into late
evening/early overnight. This corridor of convective development
includes central/southern Lower Michigan into Ohio/northwest
Pennsylvania, although there is some west/east spatial uncertainty
related to capping aloft. This activity may grow upscale and evolve
into an MCS tonight that spreads southeastward across the region,
fueled by ample source-region buoyancy. Isolated instances of large
hail are possible, but damaging winds should become the more common
hazard.
...North Dakota/Northern Plains...
In the wake of a decayed convective cluster and remnant MCV moving
into southern Manitoba this morning, height falls will continue to
occur with multiple convectively augmented mid-level disturbances
glancingly influencing the region later today. A moist boundary
layer will exist across much of North Dakota and nearby parts of
South Dakota/Minnesota, along and north-northeast of a wavy surface
front. Isolated deep convective development will be possible by late
afternoon/early evening, particularly across northern North Dakota
near this boundary, with other storms development potentially moving
into the region from southern portions of Saskatchewan/Manitoba.
Where sustained storms do occur, relatively strong wind profiles
(40-45 kt effective shear) will support some semi-organized and
sustained storms. This may include a few supercells, in the presence
of modestly steep mid-level lapse rates and moderate buoyancy, which
will be weaker and rooted above the surface with eastward extend
into eastern North Dakota/northern Minnesota. Some severe hail will
be possible regionally along with the possibility of localized
severe-caliber wind gusts.
..Guyer/Goss.. 08/23/2023
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