Aug 29, 2026 0600 UTC Day 1 Convective Outlook
Updated: Sat Aug 29 05:54:55 UTC 2026 ( | | )
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
Probabilistic Tornado Graphic
Day 1 Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
CIG1
233,807
4,481,216
Salt Lake City, UT...Fort Collins, CO...West Valley City, UT...Provo, UT...West Jordan, UT...
15 %
50,823
2,508,886
Salt Lake City, UT...West Valley City, UT...Provo, UT...West Jordan, UT...Orem, UT...
5 %
553,489
10,608,700
Denver, CO...Aurora, CO...Des Moines, IA...Lakewood, CO...Sioux Falls, SD...
Probabilistic Large Hail Graphic
Day 1 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
253,796
5,544,252
Des Moines, IA...Salt Lake City, UT...West Valley City, UT...Provo, UT...West Jordan, UT...
SPC AC 290554
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Sat Aug 29 2026
Valid 291200Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
EASTERN NEVADA...NORTHERN UTAH...AND SOUTHWEST WYOMING...
...SUMMARY...
Widely scattered strong to severe storms are expected across parts
of the northern Great Basin and northern/central Rockies. Severe
wind gusts are the main threat. Isolated severe storms are also
possible across portions of the northern Plains, with potential for
large hail and damaging wind.
...Great Basin/Rockies...
An upper low over the Pacific Northwest is forecast to merge with a
broad southern steam upper trough over the Great Basin. A belt of
enhanced mid-level flow and tropical moisture will overspread the
Great Basin and central Rockies. Clouds, showers and some
thunderstorms are likely to be ongoing early in the period
complicating expectations for diurnal heating and subsequent
destabilization. Still, filtered heating should allow for additional
storms to develop through the day along a weak front and across the
higher terrain from eastern NV into northern UT and the central
Rockies. Sufficiently strong unidirectional effective shear profiles
and a well-mixed boundary layer will promote a few organized
clusters and potentially transient supercell structures capable of
severe wind gusts and marginally severe hail.
...Four Corners...
On the southern fringes of upper trough moving through the Great
Basin, strong heating of a monsoon air mass should allow for the
development of scattered to numerous thunderstorms across northern
AZ and southern UT. Deep-layer flow here will be considerably weaker
compared to points farther north, but sight enhancement could still
support some clustering of thunderstorms. Steep low/mid-level lapse
rates, PWATs over 1 inch and numerous storms may bolster downdrafts.
Isolated severe gusts are possible as storms spread eastward into
southwestern CO and NM through the afternoon/evening.
...Northern Plains..
Several embedded disturbances within the enhanced southwesterly flow
aloft will help deepen a lee trough/low across eastern WY and
western SD this afternoon. Strengthening southerly upslope flow will
advect upper 60s F dewpoints into the region aiding in moderate
destabilization. However, widespread mid/upper-level cloud cover and
weak overall forcing for ascent cast some uncertainty on storm
development through the afternoon. If storms do develop, moderate
buoyancy and elongated mid/upper-level hodographs would support
supercells with the potential for damaging winds and hail.
The more likely scenario is that high-based convection emanating
from central WY will spread eastward late in the afternoon/early
evening with the potential for isolated damaging gusts. Some
intensification of this convection may occur as it encounters the
more unstable air mass into the overnight hours, though CAM
solutions are varied.
...IA/MN...
A remnant cluster of storms or a weakly organized MCS is likely to
be ongoing at the start of the period along the front from
southwestern MN into northern IA. Driven by strong overnight warm
advection at the terminus of the low-level jet, weak buoyancy, but
relatively strong deep-layer shear could support an isolated risk
for hail or damaging gusts for a couple of hours during the morning.
Weakening ascent and increasing mid-level heights should limit the
severe risk through the remainder of the day.
...Atlantic Coast...
Scattered thunderstorms are likely along typical sea breeze
boundaries and a weakening front from the Carolinas to FL this
afternoon. An unstable, high PWAT, but very weakly sheared air mass
will support multicell storms with sporadic wet microburst
potential. However, confidence in a more widespread or organized
severe risk remains below 5%.
..Lyons/Wendt.. 08/29/2026
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