LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sat Jul 01 2023
Valid 011200Z - 021200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
EASTERN MISSOURI...CENTRAL AND SOUTHERN ILLINOIS...WESTERN INDIANA
AND WESTERN KENTUCKY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF SOUTHEAST
NM INTO WEST TX...
...SUMMARY...
Severe thunderstorms are possible today from the central and
southern Appalachians region westward through the Ohio/Tennessee
Valleys into the mid-Mississippi Valley. Severe winds gusts, hail,
and a tornado or two will all be possible.
...Mid MS Valley into parts of the OH Valley and central
Appalachians...
An active severe-weather day appears possible from parts of the mid
MS Valley into the OH Valley, as a mid/upper-level trough moves
eastward and impinges upon a moist and favorably unstable
environment. However, the details remain uncertain, due to the
influence of rather extensive morning convection on the position of
an outflow-reinforced surface boundary, and northward extent of the
stronger diurnal destabilization.
In general, morning storms could pose an isolated hail and
wind-damage threat across parts of the OH Valley, and potentially
farther west into eastern portions of the central Great Plains. An
increase in storm coverage and intensity is expected during the
afternoon, including the potential for organized surface-based
development in areas where stronger diurnal heating/destabilization
can occur. Moderate southwesterly midlevel flow will generally
support 30-35 kt of effective shear (potentially higher near any
remnant surface boundaries), with organized clusters and a few
marginal supercells possible.
Instability will be sufficient to support a hail threat with any
discrete or clustered cells. A tornado or two will also be possible
if any supercells can be sustained, especially near any remnant
boundaries. A tendency toward upscale growth is expected with time,
but it remains unclear if a larger-scale MCS will develop, or if
multiple smaller-scale clusters will move across the region. In
either scenario, swaths of damaging wind will be possible this
afternoon and evening. Convection will eventually spread east of the
more favorable instability, but some threat could spread into the
upper OH Valley and central Appalachians this evening before
substantially weakening.
...TN Valley into parts of the Southeast/Carolinas/Virginia...
A somewhat separate area of storm development will be possible
across parts of the TN Valley into the southern Appalachians,
potentially near the remnant outflow from morning convection to the
north. Deep-layer shear will be increasingly marginal with southward
extent, but a few stronger outflow-driven clusters could eventually
spread into parts of the Southeast, Carolinas, and Virginia with a
threat of locally damaging gusts.
...Parts of the Northeast...
Increasing low-level moisture will support potentially moderate
buoyancy this afternoon across parts of the Northeast, and scattered
thunderstorm development will be possible along/ahead of a weak
surface trough. Weak low/midlevel flow and poor midlevel lapse rates
should generally limit the severe threat, but stronger upper-level
flow may help to support a few weakly organized cells/clusters
capable of locally damaging gusts and/or marginal hail.
...TX Trans Pecos/Permian Basin region...
Moderate to locally strong buoyancy may develop across parts of the
TX Permian Basin and Trans-Pecos regions this afternoon, and
scattered thunderstorm development will be possible near an
outflow-reinforced front, and also across the higher terrain.
Deep-layer shear will generally be rather weak, though somewhat
stronger shear will be possible near and immediately north of the
surface boundary. A few stronger cells/clusters will be possible,
with a threat of hail and localized severe gusts.
..Dean/Weinman.. 07/01/2023
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