SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Aug 01 2024
Valid 011200Z - 021200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
MIDWEST AND OHIO VALLEY...
...SUMMARY...
Severe thunderstorms will be possible today across parts of the
Midwest and Ohio Valley, with a threat of damaging winds, isolated
hail, and a tornado or two.
...Synopsis...
A seasonably deep trough and embedded midlevel cyclone are forecast
to move east-southeastward across parts of the upper MS Valley/Great
Lakes today. One or more MCVs may move along the southern/eastern
periphery of this trough from the mid MS Valley into the OH Valley.
Farther east, a weak mid/upper-level trough is forecast to move
eastward through parts of the Mid Atlantic/Northeast early in the
day. At the surface, an outflow-reinforced cold front will move
southward and may become nearly stationary somewhere over the
south-central Great Plains by this afternoon. Other outflow
boundaries will likely reside somewhere across the mid/upper MS and
OH Valleys.
...Parts of the Midwest/Ohio Valley...
Uncertainty remains regarding the influence of early morning
convection and related outflow on the severe potential across parts
of the Midwest and Ohio Valley. However, potential for organized
severe storms remains evident, with a threat of damaging wind,
isolated hail, and possibly a tornado or two. The Slight Risk has
been expanded across parts of the Midwest/Ohio Valley, and a
corridor of greater severe probabilities may eventually be needed,
depending on the evolution of morning convection and subsequent
destabilization.
An MCS or its remnant will likely be ongoing at the start of the
period somewhere from far eastern MO into IL. Uncertainty remains
regarding the evolution and intensity of this potential MCS through
the morning, but at least isolated damaging wind will be possible as
it moves eastward. Depending on the timing of this system, there
will be some potential for diurnal intensification as the downstream
environment destabilizes, though deep-layer flow/shear will tend to
weaken with eastward extent.
In the wake of the morning convection, diurnal heating of a very
moist airmass will support strong destabilization along/south of the
remnant outflow boundary, with some potential for recovery and
destabilization to the cool side of the boundary through the day.
The approaching shortwave trough will support scattered afternoon
storm development across parts of the mid MS Valley into the OH
Valley.
Deep-layer shear will be sufficient for storm organization, given
the favorable instability. Some supercell potential will be possible
with initial development, with an attendant threat of damaging wind,
hail, and possibly a tornado or two, especially in closer proximity
to any remnant outflow boundary. Storm clustering and some upscale
growth will be possible with time, which could result in a
forward-propagating MCS with increasing damaging-wind potential.
Farther northwest, additional strong to locally severe storm
development will be possible closer to the midlevel cyclone across
parts of WI into eastern IA and northern IL. Deep-layer shear will
likely remain rather modest, but moderate instability could support
at least isolated hail and damaging wind with the strongest storms.
...Mid Atlantic/Carolinas/Georgia...
Strong heating of a moist environment will result in the development
of moderate to locally strong buoyancy from GA and the Carolinas
into parts of the Mid Atlantic. With generally weak large-scale
ascent across the region, storm coverage remains uncertain and could
be relatively limited. However, isolated storm development will be
possible by late afternoon into early evening, as MLCINH erodes.
Modest midlevel northwesterly flow in the wake of the departing
upper-level trough could provide sufficient effective shear for some
storm organization, with a threat of isolated damaging wind and
perhaps some hail.
...Northeast NM into parts of the southern Plains...
As the outflow-reinforced front becomes nearly stationary somewhere
over the south-central High Plains into northeast NM, scattered
thunderstorms will become possible this afternoon. Initial
development may occur near the Raton Mesa vicinity, with more
isolated development possible farther east along the front into the
TX/OK Panhandles, and potentially farther east along the boundary
into northern OK/AR. Low/midlevel flow will be rather weak, but with
sufficient veering of winds with height to support effective shear
of 20-30 kt, sufficient for some storm organization in the presence
of moderate to strong buoyancy. Initial discrete storms could
produce some hail, but outflow production and consolidation within
the well-mixed environment will lead to an increasing threat for at
least isolated severe gusts later in the storm evolution.
...Arizona...
00Z guidance has trended somewhat stronger with destabilization and
potential storm coverage across parts of southeast into northern AZ.
Modest southeasterly midlevel flow could support a few briefly
organized storms, and isolated strong wind gusts and small to
marginally severe hail cannot be ruled out. Severe probabilities may
eventually be needed if confidence increases in the development of
robust storms.
..Dean/Weinman.. 08/01/2024
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