Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0754 PM CDT Thu May 28 2026
Valid 290100Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
OREGON INTO EASTERN WASHINGTON AND NORTHERN IDAHO...
...SUMMARY...
Scattered severe thunderstorms remain possible this evening east of
the Cascades in Washington and Oregon into western Idaho and
Montana. The primary hazards will be large hail and scattered severe
wind gusts.
...Synopsis...
As of 01 UTC, scattered to widespread thunderstorms continue to
develop ahead of an inverted trough axis from central OR (where a
more focused vorticity maximum is noted in GOES imagery) into
north-central MT. More isolated and short-lived convection continues
to develop within a weak up-slope flow regime along the CO front
range. While the potential for severe convection should quickly wane
after 03 UTC across the central High Plains, a severe hail and wind
threat will persist through late evening across the Pacific
Northwest.
...Pacific Northwest...
Regional radar depicts a myriad of convective modes ranging from
broken bands across central OR to splitting supercells across
eastern WA, ID, and northwest MT. This activity will continue to
spread northwestward as the inverted mid-level trough shifts west
towards the Pacific Northwest coast through tonight. A combination
of surface dewpoints in the 50s and cool mid-level temperatures
(associated with the mid-level trough axis) continue to support
MLCAPE values on the order of 1000-2000 J/kg. This buoyancy axis
should spread northwest in tandem with ongoing storms and help
maintain some degree of intensity over the next several hours.
Per regional VWP observations, mid-level winds across WA/ID remain
near 40-50 knots with decreasing magnitudes with northward extent
into eastern WA and northern ID. Despite the weaker deep-layer wind
shear, dewpoint depressions on the order of 25-30 F hint that a
deeply-mixed boundary layer remains in place downstream of
approaching storms. The onset of nocturnal cooling should be too
shallow/insufficient to offset downdraft accelerations through the
lowest 1-2 km as convection spreads northwest and cold pools begin
to amalgamate. Recent CAM guidance shows fairly strong agreement in
a substantial wind threat spreading north/northwestward across
eastern WA and northern ID later this evening. Consequently, 15%
wind and the intensity level 1 contour have been expanded to account
for this potential.
...Colorado...
Convection across the CO Front Range has been fairly transient and
tied to the terrain over the past couple of hours, largely due to
the weak up-slope flow regime. However, latest GOES imagery
continues to show deep cumulus development in proximity to the
Denver area, and recent RAP mesoanalysis show sufficient deep-layer
wind shear for at least transient organized convection capable of a
brief large hail threat. This environment, and the overall severe
threat, should wane through 03 UTC.
..Moore.. 05/29/2026
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