WW 538 SEVERE TSTM AZ 042130Z - 050500Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 538
NWS Storm Prediction Center Norman OK
230 PM MST Tue Aug 4 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southeast Arizona
* Effective this Tuesday afternoon and evening from 230 PM until
1000 PM MST.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Isolated large hail events to 1 inch in diameter possible
SUMMARY...Thunderstorms are developing over the higher terrain of
east-central Arizona. Somewhat similar to yesterday, these storms
will track southwestward through the evening, posing a risk of
damaging wind gusts.
The severe thunderstorm watch area is approximately along and 60
statute miles east and west of a line from 30 miles north of Safford
AZ to 40 miles west southwest of Sierra Vista AZ. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
07025.
...Hart
WW 0538 Status Updates
STATUS REPORT ON WW 538
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 N SAD TO
40 SE SAD.
..KERR..08/05/26
ATTN...WFO...TWC...
STATUS REPORT FOR WS 538
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
AZC003-009-019-023-050240-
AZ
. ARIZONA COUNTIES INCLUDED ARE
COCHISE GRAHAM PIMA
SANTA CRUZ
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
MD 1834 CONCERNING SEVERE THUNDERSTORM WATCH 538... FOR SOUTHEASTERN ARIZONA
Mesoscale Discussion 1834
NWS Storm Prediction Center Norman OK
0751 PM CDT Tue Aug 04 2026
Areas affected...southeastern Arizona
Concerning...Severe Thunderstorm Watch 538...
Valid 050051Z - 050245Z
The severe weather threat for Severe Thunderstorm Watch 538
continues.
SUMMARY...Thunderstorm activity appears likely to continue to
increase, particularly to the east and south of Tucson, through 7-9
PM MST, accompanied by occasional strong to severe outflow surface
gusts.
DISCUSSION...Deep-layer mean flow across the southern Arizona/New
Mexico state border vicinity and international border remains light
and northeasterly, but mid-level flow (around 20 kt near 500 mb)
appears a bit stronger with a more prominent easterly component than
24 hours ago.
A substantive clustering of storms, which has been propagating
slowly westward off the higher terrain to the north and northeast of
Safford, has shown notable recent weakening after becoming fairly
vigorous. It seems unlikely that it will make it to the lower
deserts, where the hot and deeply mixed boundary-layer remains
characterized by rather weak instability. However, based on latest
mesoanalysis, boundary-layer instability east and south of the the
Tucson vicinity may be sufficient to maintain continuing convective
development and a southwestward propagation of the southern flank of
the cold pool over the next few couple of hours.
Later this evening, as outflow emanating from an evolving cluster
south of the international border interacts with the outflow
approaching from the northeast, there appears potential for
increasing thunderstorm development across the international border
vicinity near/south of Tucson. If this occurs, it appears that
low-level thermodynamic profiles may still be conducive to strong to
severe outflow surface gusts.
..Kerr.. 08/05/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EPZ...TWC...
LAT...LON 31960873 31480901 30850917 30070952 30091036 31001148
31821153 32001038 32331018 32710998 32690968 32290934
31960873
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 PM CDT Tue Aug 04 2026
Valid 050100Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN ARIZONA...
...SUMMARY...
Thunderstorms with severe wind gusts and hail will be possible this
evening in parts of southern Arizona, the southern Rockies, the
southern High Plains and the Upper Midwest.
...Southern Arizona...
The latest surface analysis shows a sufficiently moist airmass over
southern Arizona, where surface dewpoints are in the upper 50s to
around 60 F. This is contributing to moderate instability over parts
of southern Arizona, with the RAP suggesting that MLCAPE is in the
1000 to 2000 J/kg range. Thunderstorms have developed in the higher
terrain of southwest New Mexico. These storms will move
west-southwestward across southern Arizona this evening. In addition
to the instability, surface temperature-dewpoint spreads across this
airmass are large which is resulting in very steep low-level lapse
rates. This will contribute to a potential for severe wind gusts
this evening.
...Southern Rockies/Southern High Plains...
Scattered thunderstorms are ongoing in the southern Rockies early
this evening. These storms will move east-southeastward across
southeastern Colorado and northeastern New Mexico this evening,
where the RAP has SBCAPE around 1000 J/kg with moderate deep-layer
shear and steep low to mid-level lapse rates. The environment will
support an isolated potential for severe wind gusts and hail over
the next few hours.
...Upper Midwest...
An upper-level trough will move through the north-central U.S. this
evening. Ahead of the trough, a moist and unstable airmass will be
in place over the mid Missouri and mid to upper Mississippi Valleys.
An axis of low-level moisture is analyzed from northeast Kansas into
southeast Iowa, where surface dewpoints are in the 70s F. This is
contributing to moderate instability with the RAP showing MLCAPE in
the 2000 to 3500 J/kg range. Short-term model forecasts suggest that
scattered thunderstorms will develop near the instability axis
during the overnight period. The instability along with about 30
knots of 0-6 km shear will support an isolated wind-damage threat.
..Broyles.. 08/05/2026
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0452 PM CDT Tue Aug 04 2026
Valid 061200Z - 121200Z
An upper-level ridge over the West is likely to flatten this weekend
as upper-level troughing pushes southeast across central Canada and
as an upper low slowly approaches the British Columbia coast. The
magnitude and timing of the upper-level ridge flattening still
remains somewhat uncertain. An upper high will likely remain over
portions of the Great Basin and just west of the Four Corners
through the outlook period. Monsoonal moisture will begin to move
into southern California and the Great Basin late this week and this
weekend, but the northward extent and timing of this moisture also
remains uncertain.
...Northern Intermountain West...
Mid-level flow is forecast to increase across the northwestern US by
Day 4/Friday and continue through the weekend. This along with a
strengthened onshore pressure gradient and eventual dry cold frontal
passage will increase surface winds amid a dry airmass across the
northern Intermountain West. These winds will follow a hot and dry
period, and ERCs will be above the 90th percentile with some areas
approaching record high ERCs along with dozens of active large
wildfires. The 40% area was expanded on Day 4/Friday with another
40% area included on Day 5/Saturday. Dry/breezy conditions are
likely to continue on Day 6/Sunday, but the magnitude and location
of these conditions remain too uncertain to include probabilities at
this time.
...Southern Intermountain West...
Monsoonal moisture will slowly move west/north into southern
California and the southern Great Basin late this week and over the
weekend. Isolated mixed wet/dry storms will be on the northern
fringes of this moisture across portions of southern/central Utah,
southern Nevada, and southern California. However, considerable
uncertainty exists regarding the timing and location of the moisture
in the coming days. While confidence is higher that portions of
northwest Arizona and southern Utah will experience a mix of wet/dry
thunderstorms on Day 3/Thursday - Day 4/Friday, forecast guidance
also indicates the best chances of storms are over areas with less
receptive fuels. Additionally, forecast guidance also indicates the
possibility of multiple consecutive days of thunderstorms with
increasing PWAT values and rainfall. These reasons currently
preclude introducing probabilities for dry thunderstorms. However,
if forecast guidance indicates better thunderstorm potential farther
west/north where fuels are more receptive and consecutive days of
mixed wet/dry thunderstorms are less likely, then probabilities will
be included.
...High Plains...
A 40% area was added for portions of eastern Montana as westerly
winds will increase ahead of a cold front on Day 3/Thursday. Dry and
breezy post-frontal conditions are also likely for portions of
southeast Montana/vicinity. Portions of the southern/central High
Plains are likely to experience dry and breezy conditions this
weekend. However, there is potential for wetting rain ahead of these
conditions on portions of the southern/central High Plains, which
lowers confidence for including probabilities of critical
conditions.
..Nauslar.. 08/04/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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