Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Sep 05 2026
Valid 052000Z - 061200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS INTO SOUTHEASTERN VIRGINIA...
...SUMMARY...
The threat of strong to severe thunderstorms capable of producing
scattered damaging winds will continue this afternoon/evening across
parts of the Carolinas and southern Virginia. Isolated large hail
and severe winds may also occur over parts of the northern/central
Plains through tonight.
...20Z Update...
Only minor changes were made with this update. The SLGT Risk was
trimmed behind an east-southeastward moving band of convection
moving across the Carolinas. While isolated redevelopment cannot be
entirely ruled out in the wake of this activity, the primary severe
risk will continue spreading eastward to the coast into this
evening.
Farther west, 5-percent hail probabilities were added in parts of
the lower OH Valley. Here, relatively steep deep-layer lapse rates,
around 30 kt of effective shear, and a cellular mode may support
isolated instances of marginally severe hail.
Elsewhere, the previous forecast remains on track.
..Weinman.. 09/05/2026
.PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Sep 05 2026/
...Ohio Valley/Central Appalachians into the Mid-Atlantic and
Carolinas...
An earlier MCS across the OH Valley has weakened as it crossed/moved
eastward over the central Appalachians. The strongest remaining
convective segment is ongoing late this morning across parts of
southwest VA/northeast TN. Robust destabilization is expected to
continue this afternoon downstream of this activity across southern
VA into the Carolinas, with MLCAPE peaking around 2500-3500 J/kg
over central/eastern NC. This region will be on the southern
periphery of modestly enhanced mid-level west-northwesterly flow,
and sufficient deep-layer shear will be present to maintain some
convective organization.
Current expectations are for one or more thunderstorm clusters to
gradually increase in intensity this afternoon as they spread
eastward across southern VA and central/eastern NC, with some
uncertainty whether the ongoing convection will restrengthen, or if
new development will occur along its outflow. Regardless, latest
guidance and observational trends still suggest that a relatively
greater threat for damaging winds should exist this afternoon across
central/eastern NC and vicinity, where the greatest thunderstorm
coverage, maxima in MLCAPE/DCAPE, and steepened low-level lapse
rates are forecast. Have therefore introduced higher severe wind
probabilities (30% area) across this region. Isolated hail may also
occur with the strongest cores that can develop, although mid-level
lapse rates are expected to remain rather poor. Severe potential
should gradually wane this evening with the loss of daytime heating,
and as convection moves offshore.
Farther west, outflow from the morning thunderstorms may serve as a
focus for renewed thunderstorm development this afternoon from parts
of the OH Valley southeastward into the TN Valley. This region will
be displaced from the stronger flow aloft present over the
Mid-Atlantic/Northeast, with weak deep-layer shear expected. Still,
some risk for isolated damaging winds may exist with any loosely
organized cells/clusters that can develop given the presence of
moderate to locally strong instability.
...Northern/Central Plains...
A highly amplified mid/upper-level ridge will remain anchored over
the central CONUS into south-central Canada through the period, with
generally neutral to weakly rising mid-level heights expected over
the northern/central Plains. Ongoing elevated cells across northern
ND may continue to pose an isolated severe hail threat in the short
term, but weakening low-level warm advection should tend to result
in a further decrease in intensity with this activity. Otherwise,
additional isolated to perhaps widely scattered high-based
thunderstorms may develop this afternoon along/east of a surface lee
trough over the northern/central Plains. While mid-level flow and
related effective bulk shear should remain weak, occasional severe
gusts may still occur with convective downdrafts given a well-mixed
boundary layer. Some risk for hail and gusty winds may also exist
with elevated convection that should eventually develop tonight into
early Sunday morning in a renewed/modest low-level warm advection
regime.
...Western Montana...
To the east of a closed mid-level low over WA/OR, a belt of enhanced
southwesterly mid/upper-level winds will extend across the northern
Rockies. Gradually increasing moisture and large-scale ascent aloft
associated with a weak/embedded shortwave trough are expected to
support an increase in isolated thunderstorms this
afternoon/evening. Lapse rates through low/mid levels will be steep
with strong deep-layer shear present, but modest low-level moisture
should limit MLCAPE to generally less than 500 J/kg. The potential
for severe wind gusts still appears too low to justify including 5%
wind probabilities at this time.
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