LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0242 PM CDT Fri Aug 28 2026
Valid 282000Z - 291200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL/NORTHERN PLAINS...GREAT BASIN AND DESERT SOUTHWEST INTO THE
NORTHERN ROCKIES...NORTH GEORGIA INTO THE CAROLINAS AND
MID-ATLANTIC...AND PARTS OF CENTRAL/EASTERN MAINE...
...SUMMARY...
Isolated strong to severe storms are possible across the central and
northern Plains, northern Georgia into the Carolinas and
Mid-Atlantic, central and eastern Maine, and from parts of the Great
Basin and Desert Southwest into the northern Rockies.
...20z Update...
The previous forecast largely remains on track with only minor edits
required - primarily to the general thunder line to reflect recent
convective trends. Weak/poorly organized convection ongoing across
the Mid-Atlantic and portions of Maine should continue to pose a
localized severe threat (mainly damaging wind) through late
afternoon. See MCDs #2162 and #2163 for additional short-term
details. Transient downbursts have been noted across the greater
Houston, TX area over the past 1-2 hours as thunderstorms develop
along the sea breeze. While small swaths of damaging wind may occur
with the more intense downbursts, this threat is expected to remain
fairly transient given poor deep-layer wind shear across the region
(wind speeds are generally 15 knots or less through the column per
regional VWPs).
Across the Great Basin, slight expansions of the 5% wind
probabilities were made to better reflect trends in recent
time-lagged CAM guidance. Some of the more aggressive solutions -
notably recent runs of the RRFS - hint at one or more corridors of
higher severe wind potential across eastern WY into SD as high-based
convection encounters richer low-level moisture/buoyancy over the
Plains. However, these solutions are exhibiting a considerable warm
bias compared to current observations and suggest that any residual
inhibition should be mixed out by this point in the day. Latest GOES
imagery and regional 18z soundings both depict lingering inhibition,
which casts considerable uncertainty onto the accuracy of the more
aggressive solutions.
..Moore.. 08/28/2026
.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 28 2026/
...Maine...
Morning surface analysis places a low over eastern Quebec, with a
cold front extending southward from this low through northern NY
before arcing more southwestward and becoming increasingly diffuse
across the Upper OH Valley. A shortwave trough is forecast to
progress through southern Quebec towards the St. Lawrence Valley
today. The surface low is forecast to eject northeastward in
response, with its attendant cold front sweeping eastward across ME.
A moist airmass precedes this front, with current observations
sampling mid to upper 60s dewpoints. This airmass should destabilize
amid filtered daytime heating ahead of the front, although poor
mid-level lapse will limit the overall buoyancy. Scattered
thunderstorm development is anticipated as the cold front interacts
with this modestly buoyant airmass. A few strong to severe storms
are possible, but deep-layer shear largely parallel to the frontal
boundary will contribute to a predominantly linear mode and a likely
trend toward undercutting of new updrafts. Even so, any updrafts
that can mature could organize, potentially becoming supercell
storms capable of locally wind gusts and hail.
...Mid-Atlantic into Georgia...
Morning surface analysis places a low off the southern New England
coast and another over southern NJ (near the ongoing thunderstorms).
A weak front extends through these two lows, continuing
southwestward across the Carolina Piedmont into northern GA. Widely
scattered thunderstorms are expected to form along
the front this afternoon, with slow-moving but strong storms
possible. The stronger (but still modest) deep-layer shear will
occur across VA and NC, with the stronger buoyancy displaced farther
south across SC and GA. Even so, the expectation is that a
combination of moderate CAPE, high PWAT values, and limited
deep-layer shear will promote isolated strong storms capable of
water-loaded downbursts.
...Great Basin through Wyoming..
A belt of stronger mid-level flow currently extends from central CA
through the northern Rockies between the upper troughing over
western Canada and the upper ridging centered over the Four Corners.
Low-amplitude shortwave troughs embedded within this enhanced flow,
and associated ascent and mid-level moisture, will contribute to
thunderstorm development this afternoon. A deeply mixed boundary
layer is anticipated throughout much of this region, suggesting any
of the stronger, more persistent storms could produce damaging
gusts. Highest storm coverage is expected from eastern NV into
central/northern UT, resulting in a relatively greater threat for
damaging gusts within this corridor.
...Dakotas into western Minnesota and northern Iowa...
There could potentially be two rounds of convection across the
northern Plains today. The first will be with any of the high-based
convection from WY as it spreads eastward into western
Dakotas, where greater low-level moisture and buoyancy will be in
place. The greater buoyancy could result in reintensification and a
few bowing structures capable of producing locally damaging wind
gusts and hail.
Additional warm-air advection associated development is then
possible later this evening as the low-level jet strengthens over
the Plains. These elevated storms should develop within an
environment characterized by moderate buoyancy and deep-layer shear,
suggesting a few supercells capable of large hail are possible
initially. Over time, some upscale growth is possible, which could
result in a low-probability risk for damaging gusts over southwest
MN and adjacent northwest IA early tomorrow morning.
Read more CHECK UPDATE ZOOM GRAPHIC
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