Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1258 AM CDT Thu May 28 2026

Valid 281200Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE PACIFIC NORTHWEST...

...SUMMARY...
Thunderstorms with severe wind gusts, large hail and an isolated
tornado threat are expected across parts of the Pacific Northwest
this afternoon and evening.

...Pacific Northwest...
An upper-level low will remain over central California today. On the
northern periphery of the system, bands of large-scale ascent will
move westward across the Pacific Northwest, providing support for
thunderstorm development. At the surface, a low will deepen and move
northwestward from eastern Oregon into southern Washington. A
surface trough will extend southward from the low into north-central
and west-central Oregon. Thunderstorms are forecast to first develop
across southern Oregon around midday, with convective coverage
gradually increasing over much of Oregon during the afternoon. A
larger-scale line segment is expected to organize and move
northwestward across Oregon late this afternoon and into southern
Washington early this evening.

As surface temperatures warm today, instability will increase along
the surface trough with MLCAPE expected to peak in the 1200 to 1500
J/kg range. The instability combined with 30 to 40 knots of
mid-level east-southeasterly flow, along with low to mid-level lapse
rates in the 8 to 8.5 C/km range, will support severe thunderstorm
development. This environment will be favorable for severe wind
gusts and isolated large hail within the stronger parts of an
extensive line segment. Near the surface trough, 0-3 km
storm-relative helicity is forecast to increase into the 200 to 250
m2/s2 range by late afternoon, which could also support an isolated
tornado threat. Any tornado threat would mainly be associated with
rotating elements embedded in the line. As the line moves
north-northwestward and expands, a severe threat is expected to move
into southern Washington by early evening. A marginal severe threat
could impact parts of central and northern Washington later in the
evening.

...East-central Colorado...
A mid-level trough will move northward across the central Plains
today. At the surface, upslope east-southeasterly flow will be in
place across eastern Colorado. Along the Front Range, the Denver
Cyclone is expected to develop by afternoon. Topographic lift and
increasing low-level convergence will result in scattered
thunderstorm development from the Palmer Divide northward into
north-central Colorado. Forecast soundings along this corridor by
late afternoon have 0-6 km shear in the 20 to 30 knot range with
700-500 mb lapse rates around 8 C/km. This should support a hail
threat with the stronger cells.

..Broyles/Chalmers.. 05/28/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1251 AM CDT Thu May 28 2026

Valid 291200Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER WESTERN AND
CENTRAL MONTANA...AND PARTS OF THE CENTRAL HIGH PLAINS AND SOUTHERN
PLAINS...

...SUMMARY...
A few storms may produce marginal hail or strong gusts from eastern
New Mexico and western Texas across Oklahoma and toward northern
Louisiana on Friday. A few strong to severe storms may also occur
across western Montana with gusty winds and marginal hail. Isolated
damaging wind gusts are also possible across portions of the central
High Plains.

...MT...
An upper low will weaken as it moves from the Great Basin to the
central Rockies, with cool temperatures aloft persisting over much
of the region. A surface trough will deepen over central MT with a
cold front moving across ID and into western MT. Daytime heating and
steepening lapse rates may aid wind gust potential as storms develop
late in the day from western into central MT. Relatively strong
upper-level winds will elongate hodographs, and may support cells
producing marginal hail.

...Central High Plains...
Low-level moisture will spread westward into northern CO and eastern
WY as a low pressure trough develops from MT into eastern CO during
the afternoon. Steep lapse rates and 50s F dewpoints will result in
perhaps 1000 J/kg MUCAPE supporting storms forming from southeast WY
into the Front Range. These storms may produce strong to locally
severe outflow winds.

...Southern Plains...
An upper-level jet of 50-70 kt will move into southern NM and
western TX, though midlevel winds will be at or below 30 kt. Strong
heating will occur over the region while southeast surface winds
maintain moisture influx. Storms should form during the afternoon
from eastern NM and spread across western TX and perhaps into
southwest KS. Cool midlevel temperatures may support marginal hail,
though gusty outflow winds will be the most common threat.
Additionally, a few storms may occur farther east from OK into
northeast TX, AR and LA where dewpoints and instability will be
greater. Any storms that can form within the uncapped air mass would
likely move southeastward with isolated strong gust potential.

..Jewell.. 05/28/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1247 AM CDT Thu May 28 2026

Valid 281200Z - 291200Z

...Synopsis...
A high amplitude blocking pattern will continue as an upper low
remains centered over the western CONUS with downstream ridging
across the northern High Plains/Upper Midwest. The main trough axis
will gradually lift into the central Plains while moisture advection
occurs ahead of the upper low, encouraging additional chances for
precipitation across the central CONUS. As upper troughing pushes
down the Eastern Seaboard, a cold front is expected to progress
southward through the Mid-Atlantic, bringing below-normal
temperatures and more opportunities for spotty precipitation.

...Great Basin and Southwest...
An upper-level low anchored over the Sierra Nevada and corresponding
surface low over western ID will bolster dry and breezy southerly
flow across portions of the Great Basin and Southwest this
afternoon. South winds of 15-25 mph, RH values of 15-20% (as low as
10% in valleys), and dry/cured fuels in lower elevations will
support Elevated to locally critical fire weather concerns across
portions of AZ and far western NM into the eastern Great Basin and
CO Western Slope.

...Northeastern Montana...
Surface troughing extending across the northern High Plains into the
Northern Rockies and surface high pressure over the Great Lakes
region will reinforce dry southeasterly flow atop recently receptive
fuels in northeastern MT. Elevated fire weather conditions are
expected as daytime relative humidity declines to around 20% and
southeasterly sustained winds increase to 15-25 mph.

..Elizalde-Garcia.. 05/28/2026

...Please see www.spc.noaa.gov/fire for graphic product...