LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1242 AM CDT Wed Aug 02 2023
Valid 021200Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MO
INTO SOUTHERN IL...
...SUMMARY...
Thunderstorms capable of producing damaging gusts, isolated hail,
and possibly a tornado are possible from central Missouri into
southern Illinois, mainly this afternoon and evening. Isolated
strong to severe thunderstorms are also possible across the Upper
Great Lakes region and central High Plains.
...Missouri into southern IL and vicinity...
Another round of widespread elevated convection will likely be
ongoing at the start of the period from MO into southern IL and
vicinity, as a southwesterly low-level jet impinges upon a
persistent baroclinic zone. This convection may tend to diminish
somewhat by late morning/early afternoon, potentially allowing for
several hours of diurnal heating and outflow modification, and
development of moderate to locally strong buoyancy by late
afternoon.
Meanwhile, an MCV originating from the central High Plains is
forecast to approach the lower MO River Valley during the afternoon
and evening, resulting in renewed thunderstorm development near and
to the cool side of an outflow-reinforced surface boundary. Modestly
enhanced low/midlevel flow will support sufficient effective shear
for organized convection, and supercells may evolve out of initial
redevelopment within a moist and moderately unstable environment.
The extent of enhancement to low-level shear/SRH remains uncertain,
but may be sufficient to support a tornado or two, depending in part
on the extent of outflow modification to the cool side of the
boundary. A threat for isolated damaging wind and hail would also
accompany any sustained supercells.
With rather weak upper-level flow across the region and potential
for storm interactions/mergers, a rather quick transition to
outflow-driven clusters may occur by early evening, potentially
spreading a damaging-wind threat southeastward toward the lower OH
Valley before convection weakens late tonight.
...Upper Great Lakes vicinity...
Diurnal heating of a relatively moist environment is expected to
result in moderate destabilization this afternoon from MN into parts
of the upper Great Lakes. Meanwhile, modest northwesterly midlevel
flow will support effective shear of 30-40 kt, conditionally
favorable for organized convection. However, large-scale ascent may
be relatively limited, with a shortwave mid/upper-level trough
forecast to pass well to the north across Ontario, and the trailing
cold front not expected to approach the area until tonight. As a
result, storm coverage may remain limited, but development of
isolated cells/clusters will be possible during the
afternoon/evening as MLCINH weakens. Hail and locally damaging gusts
will be the primary threats with any sustained stronger storms.
...Central High Plains...
Relatively rich low-level moisture will again support moderate
destabilization across parts of the central High Plains this
afternoon, and scattered thunderstorm development is expected from
eastern CO into adjacent portions of southwest NE and western KS.
Deep-layer shear is expected to remain rather weak, but isolated
severe outflow gusts will be possible, especially in areas where
stronger pre-convective heating occurs.
..Dean/Bentley.. 08/02/2023
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