SPC Sep 30, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0756 PM CDT Tue Sep 29 2026

Valid 300100Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
SOUTHERN/EASTERN NM INTO WEST TX...

...SUMMARY...
Isolated severe thunderstorm wind gusts and possibly a tornado or
two could occur tonight from southern and eastern New Mexico into
west Texas.

...Southern/eastern NM into west TX...
A mid/upper-level cyclone is moving across the Desert Southwest this
evening. In advance of this system, the remnants of Tropical Cyclone
Polo are moving northeastward across northern Mexico. Increasing
large-scale ascent, combined with low-level moisture transport from
the southeast and midlevel moisture downstream of the Polo remnants,
is driving an increase in storm coverage from the TX Panhandle into
eastern NM this evening. While midlevel lapse rates are poor due to
the influence of the tropical system, the rich moisture is
supporting MLCAPE of 500-1500 J/kg, which will help to sustain
widespread convection through the evening.

Moderate deep-layer shear will persist downstream of the approaching
mid/upper-level low/trough, while increasing low-level mass response
will result in strengthening effective SRH with time tonight.
Occasional supercell structures have been noted from southeast NM
into the TX Panhandle, with additional rotating storms possible
through the evening as storm coverage continues to increase.

The thermodynamic environment is not favorable for an organized
severe-wind threat, while low-level shear/SRH may only be supportive
of a brief tornado threat, given the marginal buoyancy and a
tendency toward more linear structures with time. As a result, the
severe threat may tend to be limited in magnitude, though localized
strong to severe gusts and a brief tornado or two will be possible
with any persistent organized storm structures through late tonight.

See MCDs 2335 and 2336 for more information regarding the short-term
threat across this region.

..Dean.. 09/30/2026


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SPC Sep 29, 2026 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 PM CDT Tue Sep 29 2026

Valid 292000Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
ARIZONA ACROSS SOUTHERN/EASTERN NEW MEXICO INTO WEST TEXAS...

...SUMMARY...
Isolated severe thunderstorm wind gusts and possibly a tornado or
two could occur this afternoon into tonight from southeast Arizona
across southern and eastern New Mexico into west Texas.

...20z Update...
No changes were made to the existing severe probabilities with this
update as the forecast remains generally on track. An increase in
thunderstorm coverage (likely in the form of a complex/linear storm
mode) is expected this afternoon/evening as the remnant core of Polo
progresses northeastward into the southern High Plains. As this
occurs, isolated severe wind gusts and perhaps a tornado or two may
occur, with locally greater potential possible from southeastern New
Mexico into West Texas where less prevalent cloud cover has allowed
for stronger diurnal heating through mid afternoon. See the
discussion below for additional details.

..Chalmers/Thornton.. 09/29/2026

.PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Sep 29 2026/

...Synopsis...
Fairly complex synoptic evolution is anticipated today through
tonight as a remnants of what is currently Hurricane Polo become
absorbed within the circulation of the deepening mid-latitude
cyclone currently centered over the Lower CO River Valley. In
general, the Lower CO River Valley cyclone is forecast to deepen as
it gradually shifts eastward. In response, Hurricane Polo is
forecast to move quickly northeastward across Sonora and into New
Mexico. Polo is forecast to weaken over the mountainous terrain of
northern Mexico, but will likely maintain some of its warm-core
characteristics through at least tomorrow morning. Additionally,
mass response across the southern High Plains will result in
increasing low-level moisture advection across the southern Plains
while also aiding in surface cyclogenesis across central and eastern
NM late tonight/early tomorrow.

...Southern Arizona...
Recent surface analysis reveals a very moist airmass over southern
AZ, with a corridor of mid to upper 60s dewpoints extending from the
central southern border into the Phoenix vicinity. Surface analysis
also places a weak low over south-central AZ. VAD profiles from IWA
and EMX both show fairly long hodographs, supported by 30 to 40 kt
of low/mid-level southwesterly flow. Widespread showers and
thunderstorms will likely continue throughout the day, with limited
diurnal heating and weak tropical lapse rates keeping buoyancy
modest. Even so, the strong nature of the wind profiles could
support a few at least weak/transient supercells, and potentially
more organized convective bands later today, with at least some
potential for strong thunderstorm wind gusts.

...Southern High Plains...
Thunderstorm coverage is expected to increase notably this
afternoon/evening as the core of Polo progresses into the region.
Tropical character of the airmass will keep lapse rates poor while
cloud cover also limits heating, limiting the overall buoyancy.
Nonetheless, buoyant thermodynamic profiles are still expected to
result in updrafts deep enough for lightning production.
Additionally, low-level wind profiles are expected to lengthen
significantly after 00Z as the remnants of Polo interact with a
dynamically strengthening low-level jet. The widespread storm
coverage will result in a tendency toward complex or linear storm
modes with time, though a few/episodic supercells will also be
possible. A brief tornado and/or strong wind gusts could accompany
any organized, more persistent storm structures.


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SPC Sep 29, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1120 AM CDT Tue Sep 29 2026

Valid 291630Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
ARIZONA ACROSS SOUTHERN/EASTERN NEW MEXICO INTO WEST TEXAS...

...SUMMARY...
Isolated severe thunderstorm wind gusts and possibly a tornado or
two could occur this afternoon into tonight from southeast Arizona
across southern and eastern New Mexico into west Texas.

...Synopsis...
Fairly complex synoptic evolution is anticipated today through
tonight as a remnants of what is currently Hurricane Polo become
absorbed within the circulation of the deepening mid-latitude
cyclone currently centered over the Lower CO River Valley. In
general, the Lower CO River Valley cyclone is forecast to deepen as
it gradually shifts eastward. In response, Hurricane Polo is
forecast to move quickly northeastward across Sonora and into New
Mexico. Polo is forecast to weaken over the mountainous terrain of
northern Mexico, but will likely maintain some of its warm-core
characteristics through at least tomorrow morning. Additionally,
mass response across the southern High Plains will result in
increasing low-level moisture advection across the southern Plains
while also aiding in surface cyclogenesis across central and eastern
NM late tonight/early tomorrow.

...Southern Arizona...
Recent surface analysis reveals a very moist airmass over southern
AZ, with a corridor of mid to upper 60s dewpoints extending from the
central southern border into the Phoenix vicinity. Surface analysis
also places a weak low over south-central AZ. VAD profiles from IWA
and EMX both show fairly long hodographs, supported by 30 to 40 kt
of low/mid-level southwesterly flow. Widespread showers and
thunderstorms will likely continue throughout the day, with limited
diurnal heating and weak tropical lapse rates keeping buoyancy
modest. Even so, the strong nature of the wind profiles could
support a few at least weak/transient supercells, and potentially
more organized convective bands later today, with at least some
potential for strong thunderstorm wind gusts.

...Southern High Plains...
Thunderstorm coverage is expected to increase notably this
afternoon/evening as the core of Polo progresses into the region.
Tropical character of the airmass will keep lapse rates poor while
cloud cover also limits heating, limiting the overall buoyancy.
Nonetheless, buoyant thermodynamic profiles are still expected to
result in updrafts deep enough for lightning production.
Additionally, low-level wind profiles are expected to lengthen
significantly after 00Z as the remnants of Polo interact with a
dynamically strengthening low-level jet. The widespread storm
coverage will result in a tendency toward complex or linear storm
modes with time, though a few/episodic supercells will also be
possible. A brief tornado and/or strong wind gusts could accompany
any organized, more persistent storm structures.

..Mosier/Chalmers.. 09/29/2026


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SPC Sep 29, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Tue Sep 29 2026

Valid 291300Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA/NEW MEXICO TO WEST TEXAS...

...SUMMARY...
Isolated severe thunderstorm wind gusts and possibly a tornado or
two could occur this afternoon into tonight from southern and
eastern New Mexico into west Texas, and across southeast Arizona.

...Synopsis...
A mid/upper-level low and attendant trough will move across the
Desert Southwest through the period. In response to the approaching
deep trough, Hurricane Polo is forecast to move from the Gulf of
California into Sonora this morning. While the tropical cyclone is
forecast to weaken over the mountainous terrain of northern Mexico
later today, a phasing of the mid-level remnants of Polo with the
approaching deep mid/upper-level trough will result in a
consolidating surface low that is forecast to deepen and move across
eastern New Mexico and west Texas tonight.

...Southern/eastern New Mexico to west Texas...
Widespread convection is ongoing and expected to generally continue
into this afternoon and tonight from southern/eastern New Mexico to
west Texas, as increasing large-scale ascent overspreads a very
moist environment. The influence of the remnant tropical system will
result in poor mid-level lapse rates, but increasing deep-layer
flow/shear and enlarging low-level hodographs will favor some storm
organization, especially later this afternoon and evening. The
widespread storm coverage will result in a tendency toward complex
or linear storm modes with time, though a few/episodic supercells
will also be possible. The weak lapse rates and modest buoyancy are
expected to limit the overall magnitude of severe potential, but a
localized tornado and severe-gust threat could accompany any
organized storm structures, particularly this afternoon and evening,
influenced by a nocturnally strengthening low-level jet.

...Southern Arizona...
A moist environment resides in close proximity to the Southwest
Deserts mid/upper-level low, with a belt of very strong deep-layer
winds sampled in available 12z upper-air data and regional WSR-88D
VWPs. Scattered thunderstorms are common this morning, and while
this convection/related cloud cover will generally hinder overall
destabilization, modest diurnal heating will probably lead to some
convective intensification during the day. The strong nature of the
wind profiles could support a few at least weak/transient
supercells, and potentially more organized convective bands later
today, with at least some potential for strong thunderstorm winds
and mostly sub-severe hail.

..Guyer/Bentley.. 09/29/2026


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