Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Mon Aug 25 2025
Valid 252000Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
ARIZONA...
...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.
...20z Update...
Scattered storms are currently developing over parts of southern AZ
and MX ahead of a weak MCV. Additional development is expected the
remainder of the afternoon into this evening. Limited buoyancy
(MLCAPE ~1000 J/kg) will support multicell updrafts atop fairly dry
low-levels. A few of the semi-organized storm clusters could support
stronger downdrafts with damaging gust potential. Minor changes were
made to the edges of MRGL risk area, see MCD #2014 for short-term
information. Elsewhere, scattered storms are expected over the
central and western CONUS today/tonight. Limited buoyancy and
vertical shear will keep the severe risk low. See the previous
discussion.
..Lyons.. 08/25/2025
.PREV DISCUSSION... /ISSUED 1131 AM CDT Mon Aug 25 2025/
...Synopsis...
A large upper trough will remain over the eastern CONUS today, as
several embedded shortwave troughs progress within its southern
periphery. Extensive upper ridging that currently extends from the
southern Plains into the northern Intermountain West is forecast to
remain largely in place. Some dampening may occur along the
northwestern periphery of this ridging as a slow-moving vorticity
maximum continues northeastward from the CO/OR/NV border vicinity
into more of eastern OR. Ample monsoonal moisture exists beneath
this ridging, contributing to scattered to numerous thunderstorms
from the southern/central Rockies westward across the Southwest and
much of the Great Basin. Limited vertical shear and weak buoyancy
will mitigate the severe potential across the majority of the
region. The only exceptions are across central Rockies and immediate
foothills, and portions of southern AZ.
...Southern AZ...
Ample monsoonal moisture is in place across the region, evidenced by
PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z
soundings, respectively. Filtered diurnal heating within this moist
airmass will support modest buoyancy and afternoon thunderstorm
development. A belt of stronger mid-level southeasterly flow (20-25
kt) is forecast to overspread the region this afternoon, providing
ample shear for some multicell storm clusters. Initial storms which
are expected to form across the higher terrain in southeast Arizona
may result in congealing outflow with a damaging wind threat as
storms move generally west-northwestward through the evening.
...Central Rockies...
Thunderstorm development is expected across the high terrain by the
early afternoon. Poor lapse rates and cooler temperatures will keep
buoyancy will be modest, likely limiting overall updraft strength
and tempering the severe potential. Even so, moderate northwesterly
flow aloft will support long hodographs and the potential for some
storm organization if updrafts can become sufficiently deep. An
instance or two of hail is possible with any stronger, more
long-lived storms.
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