LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1246 AM CDT Sun Mar 26 2023
Valid 261200Z - 271200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF
EASTERN LOUISIANA THROUGH SOUTHERN MISSISSIPPI AND INTO SOUTHERN
ALABAMA...
...SUMMARY...
Scattered severe thunderstorms will likely occur from central
Louisiana eastward across the central Gulf Coast states and into the
Carolinas. Several tornadoes are possible, including the
possibility for a couple of strong tornadoes. A risk for large to
very large hail will probably accompany the more intense storms.
...Synopsis...
A belt of strong west-southwesterly mid-level flow will extend from
the Desert Southwest eastward across the lower MS Valley and into
the Carolinas/Mid-Atlantic states. A larger-scale trough initially
over the Interior West will deamplify as a 90-kt 500 mb speed max
moves from AZ/NM to the lower OH Valley. A lower-latitude mid-level
perturbation is forecast to move from south-central/east-central TX
to MS/AL by early evening. In the low levels, a frontal zone
initially draped from southern LA through central AL will probably
advance northward into northern LA and central MS during the day as
a weak area of low pressure develops east along the frontal zone
coincident with the mid-level speed max.
...Central Gulf Coast east to the Carolinas...
A cluster of thunderstorms may be ongoing this morning over parts of
AL/GA via low-level warm-air advection and an accompanying isolated
risk for severe thunderstorms. Model guidance seems to indicate
that this activity will persist and move east while some upscale
growth occurs during the morning. Strong effective shear (50 kt)
will support storm organization. Less certain is the evolution of
this potential storm activity as it evolves through the diurnal
heating cycle as it moves across GA into the Carolinas. Additional
storms may develop with some of these becoming supercellular while a
complex mixed convective mode (perhaps downscale growth into some
cells) may occur. Regardless, all hazards seem possible given the
ample buoyancy (500-2000 J/kg MLCAPE) forecast across parts of GA
into the Carolinas during the day.
Farther west, as the marine warm front advances slowly northward
into the lower MS Valley and south-central AL during the day, the
combination of heating and moistening of the boundary layer beneath
steep 700-500 mb lapse rates will result in a corridor of moderate
to strong buoyancy (1500-3000 J/kg MLCAPE). A gradual veering and
strengthening of flow with height will result in enlarging and long
hodographs by late afternoon/early evening. A seemingly potent
thermodynamic/kinematic setup is shown by some models from LA east
into AL. The favorable timing of the mid-level disturbance and an
intensification of the 850-mb flow will conditionally yield a
potentially very favorable corridor for intense supercells.
Isolated to scattered thunderstorms will likely develop during the
afternoon into the evening. Large to very large hail is possible
with the stronger updrafts and several tornadoes are also possible,
including a risk for a couple of strong tornadoes. A cluster of
storms will likely evolve as a LLJ intensifies by the mid-late
evening and into the overnight with a severe risk spreading east.
...IL/IN...
Low-topped thunderstorms may develop Sunday afternoon across eastern
IL as a low-amplitude shortwave trough overspreads this region.
Although low-level moisture should remain limited, enough weak
instability may still develop through the day as mid-level
temperatures cool with the shortwave trough passage. With some
enhanced low/mid-level flow forecast, and convection that can
develop and be sustained may pose an isolated damaging wind risk.
..Smith/Weinman.. 03/26/2023
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