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ACUS01 KWNS 081242
SWODY1
SPC AC 081240
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 AM CST Sun Nov 08 2026
Valid 081300Z - 091200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL
PART OF SOUTH TEXAS...
...SUMMARY...
Strong to locally severe thunderstorms may occur today across parts
of south Texas. Isolated damaging winds and perhaps a brief tornado
appear possible.
...South Texas...
Downstream of a mid/upper-level trough/low over northern Mexico,
thunderstorms are ongoing this morning across parts of south TX. A
weak surface low/inverted trough is also analyzed across this
region, with greater low-level moisture (upper 60s to low 70s
surface dewpoints) present across the lower TX Coast. Weak
surface-based instability should develop this morning as filtered
daytime heating occurs, and strong to locally severe thunderstorms
may occur near the coast in the vicinity of Corpus Christi. Modest
enhancement to the low-level winds (southeasterly around 20-25 kt;
reference 12Z CRP observed sounding) and sufficient deep-layer shear
should exist for organized updrafts, including marginal supercell
structures (with one attempt already observed southwest of KCRP).
While low/mid-level lapse rates will remain poor, any sustained
surface-based supercell could produce isolated severe/damaging winds
and perhaps a brief tornado given effective SRH around 100 m2/s2.
Otherwise, elevated thunderstorms are forecast across a broader
portion of south-central TX, as large-scale ascent preceding the
upper trough/low overlaps with a weakly unstable airmass inland.
...Pacific Northwest...
Thunderstorm potential should continue to diminish this morning as
large-scale ascent associated with a strong mid/upper-level trough
moves inland across the Pacific Northwest and western Canada. But,
occasional lightning flashes may still occur with post-frontal
low-topped convection in the short term, as cold mid-level
temperatures support weak MUCAPE.
..Gleason/Wendt.. 11/08/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261108T1242.txt
400
ACUS01 KWNS 080535
SWODY1
SPC AC 080533
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1133 PM CST Sat Nov 07 2026
Valid 081200Z - 091200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms appear unlikely across the U.S. Sunday through Sunday
night.
...South Texas...
An upper low over Sonora, Mexico, late this evening is forecast to
move/develop toward the TX Big Bend with an attending belt of
enhanced mid/upper-level flow present over central and southern TX.
The 00Z Brownsville and Corpus Christi, TX, soundings sampled a
seasonably moist air mass (e.g., PW of 1.7") advancing inland ahead
of the upper-air system with boundary-layer dewpoints expected to
rise into the low to mid 70s across Deep South TX on Sunday. That
moisture will contribute to at least marginal instability, which,
coupled with persistent low/midlevel warm advection downstream from
the upper low, will foster multiple waves of thunderstorms during
the forecast period.
A vertically veering wind profile with up to 35-40 kt of deep-layer
shear is forecast across the region on Sunday, which would
conditionally support supercell storm modes and an associated severe
weather threat. However, considerable uncertainty exists in the
extent to which the air mass can destabilize due to the deleterious
effects of convective outflow and cloud cover arising from early-day
storms. As such, no severe weather probabilities will be included in
this forecast.
...Washington...
While the strongest forcing for ascent will shift away from the
region Sunday morning, steep lapse rates in the 0-3 km layer may
support a few sufficiently deep convective updrafts for lightning
generation into afternoon.
...Lower Great Lakes and Maine...
Isolated lightning occurrences appear possible over ME Sunday
morning in association with an upper low moving through the area.
Sporadic lightning activity may also occur in the lee of the lower
Great Lakes Sunday night within a zone of strong dynamic
ascent/midlevel cooling present on the cyclonic side of
mid/upper-level wind maxima progressing into the region. In both
areas, areal lightning coverage is expected to be less than 10%.
..Mead.. 11/08/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261108T0535.txt
528
ACUS01 KWNS 080035
SWODY1
SPC AC 080033
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0633 PM CST Sat Nov 07 2026
Valid 080100Z - 081200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER NORTHWEST
WASHINGTON...
...SUMMARY...
Isolated damaging gusts may occur over portions of northwest
Washington this evening into tonight.
...Northwest Washington...
Level-1/Marginal Risk wind probabilities have been expanded inland
with this forecast update to account for a potentially wider
corridor of severe wind gust potential, mainly in the 08/02-05z
timeframe.
A strongly forced prefrontal rainband currently off the coast will
move onshore within the next hour or so before reaching the I-5
corridor by 08/05-06z. Very strong low-level flow precedes the
rainband with KLGX VWP data indicating 50-55 kt southerly winds in
the lowest km AGL. While instability remains quite weak (MUCAPE of
100-150 J/kg, per the 00Z UIL sounding), downdraft-aided turbulent
mixing in the vicinity of embedded bowing/LEWP structures may be
sufficient to support isolated severe wind gusts as the band moves
inland. A few strong to severe wind gusts and greater lightning
potential may accompany widely scattered, post-frontal convection
moving onshore in tandem with a plume of steepening 0-3 km lapse
rates.
...Central Texas into the lower Rio Grande Valley...
Downstream from an upper low over northwest Mexico, a weak
perturbation has advanced into west-central TX this evening with a
secondary, stronger impulse forecast to overspread the Edwards
Plateau overnight. Forcing for ascent associated with those features
will interact with a marginally unstable air mass (MUCAPE < 1000
J/kg) to support a gradual increase in thunderstorm coverage into
early Sunday morning, especially over the lower Rio Grande
Valley/Deep South TX. Onshore flow of an increasingly moist boundary
layer (per the 00Z BRO sounding) into those areas may allow some
storms to become surface-based amidst a modestly sheared kinematic
environment. While a strong storm or two is possible, severe weather
potential currently appears negligible.
...Maine...
Within the base of broader midlevel troughing, an intense vorticity
maximum will pivot from the Mid-Atlantic into New England overnight,
yielding strong forcing for ascent across the region. The 00Z CAR
sounding exhibited modestly steep midlevel lapse rates atop a rather
deep saturated layer, which yields MUCAPE of 200-300 J/kg -
sufficient for isolated thunderstorm development.
..Mead.. 11/08/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261108T0035.txt
328
ACUS01 KWNS 071952
SWODY1
SPC AC 071950
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0150 PM CST Sat Nov 07 2026
Valid 072000Z - 081200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ...
...SUMMARY...
Isolated damaging gusts may occur along the immediate northwest
Washington coast late this evening into tonight.
...20z Update...
No changes are needed to the current D1 Convective Outlook. See
previous discussion below for more information.
..Halbert-E.. 11/07/2026
.PREV DISCUSSION... /ISSUED 1026 AM CST Sat Nov 07 2026/
...Synopsis...
Within the primary northern stream, embedded shortwave troughs will
move from the lower Great Lakes to New England and to the Pacific
Northwest coast, respectively. Weak buoyancy rooted close to 850 mb
could support isolated lightning flashes in the zone of ascent
across southern and eastern Maine. A strong shortwave trough and
associated cold front will reach the WA coast late this
evening/early tonight, with strong winds near 100 kt in the mid
levels and 55-70 kt close to 850 mb. A forced frontal rain band is
a possibility late this evening with the potential for strong gusts
to mix down to the surface within the band. After frontal passage,
weak buoyancy will develop in the steeper lapse rate environment,
where isolated lightning flashes will be possible with low-topped
convection. There is enough convective wind potential along the
immediate northwest WA coast to justify an addition of a 5%
wind/MRGL area.
Otherwise, the potential for occasional elevated thunderstorms
(rooted near 700 mb) will continue across the Rio Grande Valley in
TX. Convection rooted near the surface will be possible across deep
South TX per the 12z BRO sounding. While a bit of an increase in
deep-layer vertical shear is expected later today, poor lapse rate
profiles and low-level vertical shear suggest little threat for
organized severe storms. Farther east, isolated convective showers
will be possible across southeast FL along a diffuse frontal zone,
though minimal forcing for ascent and the potential for substantial
dry entrainment in the mid levels will limit any thunderstorm
potential.
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261107T1952.txt
119
ACUS01 KWNS 071628
SWODY1
SPC AC 071626
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1026 AM CST Sat Nov 07 2026
Valid 071630Z - 081200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
EVENING INTO TONIGHT ALONG THE IMMEDIATE NORTHWEST WASHINGTON
COAST...
...SUMMARY...
Isolated damaging gusts may occur along the immediate northwest
Washington coast late this evening into tonight.
...Synopsis...
Within the primary northern stream, embedded shortwave troughs will
move from the lower Great Lakes to New England and to the Pacific
Northwest coast, respectively. Weak buoyancy rooted close to 850 mb
could support isolated lightning flashes in the zone of ascent
across southern and eastern Maine. A strong shortwave trough and
associated cold front will reach the WA coast late this
evening/early tonight, with strong winds near 100 kt in the mid
levels and 55-70 kt close to 850 mb. A forced frontal rain band is
a possibility late this evening with the potential for strong gusts
to mix down to the surface within the band. After frontal passage,
weak buoyancy will develop in the steeper lapse rate environment,
where isolated lightning flashes will be possible with low-topped
convection. There is enough convective wind potential along the
immediate northwest WA coast to justify an addition of a 5%
wind/MRGL area.
Otherwise, the potential for occasional elevated thunderstorms
(rooted near 700 mb) will continue across the Rio Grande Valley in
TX. Convection rooted near the surface will be possible across deep
South TX per the 12z BRO sounding. While a bit of an increase in
deep-layer vertical shear is expected later today, poor lapse rate
profiles and low-level vertical shear suggest little threat for
organized severe storms. Farther east, isolated convective showers
will be possible across southeast FL along a diffuse frontal zone,
though minimal forcing for ascent and the potential for substantial
dry entrainment in the mid levels will limit any thunderstorm
potential.
..Thompson/Barnes.. 11/07/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261107T1628.txt
863
ACUS01 KWNS 071248
SWODY1
SPC AC 071246
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0646 AM CST Sat Nov 07 2026
Valid 071300Z - 081200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe thunderstorms are not forecast through tonight.
...Synopsis and Discussion...
An upper trough/low over the lower Great Lakes this morning will
move eastward across the Mid-Atlantic and Northeast today. Modest
low-level warm advection and cool mid-level temperatures may support
weak but sufficient MUCAPE for occasional lightning flashes with
convection that develops across parts of New England through the
day. Instability is expected to remain too limited to support
organized severe thunderstorms.
Mainly elevated thunderstorms should occur through the period across
parts of west/central/south TX, as a separate mid-level trough/low
translates east-southeastward from the Southwest into north-central
Mexico. A surface front will generally remain offshore from the
lower TX Coast, but large-scale ascent preceding the upper trough
and a modest increase in low-level warm advection late this
afternoon into tonight will aid the development of MUCAPE up to 500
J/kg, which should support some lightning with this elevated
activity.
Across the coastal Pacific Northwest, a low-topped line of
convection is forecast to approach the WA Coast after 00Z, with
strong low and mid-level winds expected to be present ahead of an
approaching upper trough. Low 50s surface dewpoints and minimal
diurnal heating both appear marginal to support more than very weak
surface-based instability, and updrafts may not reach sufficient
height to induce charge separation and lightning flashes. Even so,
strong/gusty winds may occur with this convection as it spreads
inland across parts of coastal WA this evening/tonight. However,
given the very limited thermodynamic environment, confidence in
severe gusts remains too low to include any severe probabilities.
..Gleason.. 11/07/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20261107T1248.txt
