WW 248 SEVERE TSTM ID OR 281950Z - 290300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 248
NWS Storm Prediction Center Norman OK
1250 PM PDT Thu May 28 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western Idaho
Central and Eastern Oregon
* Effective this Thursday afternoon and evening from 1250 PM
until 800 PM PDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 75
mph likely
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Thunderstorms will develop and intensify across the watch
area through the afternoon, in a moderately unstable air mass. The
strongest storms will pose a risk of damaging winds and large hail
through the early evening.
The severe thunderstorm watch area is approximately along and 110
statute miles north and south of a line from 35 miles south
southwest of Redmond OR to 80 miles southeast of Baker OR. 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
1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
13030.
...Hart
WW 0248 Status Updates
STATUS REPORT ON WW 248
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..LYONS..05/28/26
ATTN...WFO...BOI...PDT...PQR...MFR...
STATUS REPORT FOR WS 248
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
IDC001-003-027-045-073-075-087-282140-
ID
. IDAHO COUNTIES INCLUDED ARE
ADA ADAMS CANYON
GEM OWYHEE PAYETTE
WASHINGTON
ORC001-013-017-021-023-025-027-031-037-045-049-055-059-061-063-
065-069-282140-
OR
. OREGON COUNTIES INCLUDED ARE
BAKER CROOK DESCHUTES
GILLIAM GRANT HARNEY
HOOD RIVER JEFFERSON LAKE
MALHEUR MORROW SHERMAN
UMATILLA UNION WALLOWA
WASCO WHEELER
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
MD 0883 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR EASTERN WASHINGTON...THE IDAHO PANHANDLE...AND FAR NORTHWEST MONTANA
Mesoscale Discussion 0883
NWS Storm Prediction Center Norman OK
0434 PM CDT Thu May 28 2026
Areas affected...eastern Washington...the Idaho Panhandle...and far
northwest Montana
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 282134Z - 282330Z
Probability of Watch Issuance...80 percent
SUMMARY...The threat for severe thunderstorms capable of 60-75 mph
wind gusts and hail up to golf-ball size is expected to increase
from south to north across the discussion area this afternoon into
evening. A Severe Thunderstorm Watch will likely be required.
DISCUSSION...Visible satellite and mosaic radar data indicate
gradually deepening convection along the Salmon River Mountains and
adjacent high terrain of the southern ID Panhandle into the
Bitterroot Mountains in western MT. Forcing for ascent downstream
from a vigorous short-wave trough pivoting northwest through the
northern Great Basin in conjunction with heating/destabilization
along the high terrain are contributing to the convective
development, with scattered thunderstorms eventually evolving in
these areas.
Strong daytime heating across the discussion area will combine with
boundary-layer dewpoints in the 50s to support further air mass
destabilization through the peak of the diurnal heating cycle, with
the presence of steep low/mid-level lapse rates yielding MLCAPE as
high as 1500-2500 J/kg. The destabilization process will coincide
with gradually strengthening mid- to high-level winds with effective
bulk shear increasing to 30-40 kt, which will favor organized storm
modes, including supercells and bowing structures capable of wind
gusts up to 60-75 mph and hail up to golf-ball size.
..Mead/Guyer.. 05/28/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MSO...OTX...PDT...
LAT...LON 45471474 45421568 45781646 46041692 46071739 46121828
46811874 47721887 48471865 48651815 48681723 48811646
48721554 48221500 47481460 46841427 46111420 45471474
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Thu May 28 2026
Valid 282000Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ...
...SUMMARY...
Scattered severe thunderstorms remain possible this afternoon and
evening over western Idaho and east of the Cascades in Washington
and Oregon, capable of damaging gusts, large hail, and perhaps a
tornado.
...20Z Update...
The previous forecast (see below) remains on track.
..Squitieri.. 05/28/2026
.PREV DISCUSSION... /ISSUED 1108 AM CDT Thu May 28 2026/
...WA/OR/ID...
Morning water vapor imagery shows an upper low over central CA, with
a strong shortwave trough rotating around the low over central NV.
This feature is forecast to move into ID/OR later today, with an
associated 40-50 knot mid level jet affecting the area. Strong
heating, dewpoints in the upper 40s-lower 50s, and steepening
mid-level lapse rates will lead to moderate CAPE values over much of
western ID into central WA/OR, setting the stage for afternoon
thunderstorms. Activity is expected to first develop across
southwest ID/southern OR, where sufficient vertical shear would
support supercell structures capable of large hail and damaging wind
gusts. Morning CAM guidance suggests activity will organize into
multiple clusters by evening, tracking northwestward across the
Columbia Basin into western/central WA. These storms would continue
to pose a damaging wind threat.
...CO...
Strong heating and sufficient low-level moisture will likely result
in widely scattered thunderstorms in the foothills of the Front
Range this afternoon. The strongest cells could produce hail.
...KS...
A remnant weak vorticity max is tracking northward near the OK/KS
border. Southeasterly low-level winds to the north of the vort max
may result in sufficient shear for weak rotation in a few storms
later today. While a brief spin-up over north-central KS cannot be
ruled out, the overall threat appears too weak for outlook
probabilities today.
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1218 PM CDT Thu May 28 2026
Valid 291200Z - 301200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
WESTERN AND NORTHERN MONTANA...THE CENTRAL HIGH PLAINS...AND THE
SOUTHERN HIGH PLAINS INTO THE CENTRAL PLAINS...
...SUMMARY...
A few storms may produce marginal hail or strong gusts from eastern
New Mexico and western Texas across Oklahoma and toward Kansas on
Friday. A few strong to severe storms may also occur across western
Montana with gusty winds and marginal hail. Isolated severe storms
are also possible across portions of the central High Plains.
...Synopsis...
A closed low across the Great Basin will become an open wave on
Friday and start to advance northeast toward the central Rockies. As
this occurs, lee troughing will begin across the southern and
central High Plains and into eastern Montana. A strong mid-level
trough will move southward across eastern Canada into the Northeast.
...Western into north-central Montana...
Weak to moderate instability will build across western Montana on
Friday as dewpoints increase into the mid 50s and mid-level
temperatures cool. Mid-level flow is forecast to increase to 25 to
30 knots across western Montana which may provide sufficient shear
for a few more organized storms. These storms should develop by
mid-afternoon and move northward, potentially growing upscale into
one or more linear structures.
...Central High Plains...
Surface moisture is forecast to back up near the terrain across
northern Colorado and southeast Wyoming on Friday. This will lead to
weak to moderate instability across the region. In addition to
typical terrain circulations, guidance suggests a weak mid-level
shortwave trough may emerge across the region and provide additional
support for storm development. Shear is forecast to remain
relatively weak, but weak to moderate instability, and steep lapse
rates will support some threat for severe wind gusts and perhaps
isolated large hail.
...Southern High Plains into the central Plains...
A southern stream mid-level jet streak is forecast to emerge from
northern Mexico into the southern High Plains Friday
afternoon/evening. This ~40 knot jet streak will overspread portions
of the southern High Plains and the dryline. This should provide
ample shear for storm organization during the afternoon/evening.
Greater storm coverage and storm organization may exist between
Midland and Amarillo at the nose of this stronger mid-level flow.
However, it appears the greater moisture will remain farther east
and thus, storm intensity maybe somewhat mitigated. Therefore,
hail/wind probabilities remain 5% at this time.
Additional storms may develop from central Kansas to north-central
Oklahoma along a frontal boundary amid weak isentropic ascent.
Greater instability is expected within this zone, however, mid-level
flow is forecast to be weaker which may challenge storm
organization.
..Bentley.. 05/28/2026
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0138 PM CDT Thu May 28 2026
Valid 301200Z - 311200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER WESTERN
NEBRASKA AND SOUTH DAKOTA...
...SUMMARY...
Scattered storms, some possibly severe with wind and hail potential,
are expected over parts of the Plains states on Saturday. The most
concentrated area is forecast to be over western Nebraska and South
Dakota.
...Synopsis...
As a mid-level shortwave trough rotates from the Rockies into the
central Plains a lee surface cylcone will develop across western
Kansas. A dryline will mix eastward across southwest Kansas into the
Texas Panhandle.
...Northern High Plains...
Moderate to strong instability is forecast to develop from northern
Oklahoma and central Kansas back into western Nebraska and southwest
North Dakota where low to potentially mid 70s dewpoints are expected
to develop northeast of a surface dryline. While most of this
dryline should remain capped due to minimal forcing, storm
development is expected across northeast Colorado and northwest
Kansas into western Nebraska during the afternoon as the mid-level
trough advects across the region and mid-level temperatures cool.
Mid-level flow is initially forecast to remain relatively weak, but
strengthen to ~40 knots by late afternoon to early evening when
storm organization may improve. Steep lapse rates will support large
hail and severe wind gusts with these storms which may eventually
grow upscale into a cluster during the evening.
...Kansas into northwest Texas...
Farther south along the dryline, forcing will remain somewhat
nebulous amid rising heights aloft and weak convergence. However,
forecast soundings show an uncapped airmass with strong heating (mid
to upper 90s). This may support a few severe storms and if they
develop, some storm organization is possible given 50 to 70 knots of
flow forecast around 300mb. Damaging winds and perhaps some large
hail would be the primary threats with this activity.
..Bentley.. 05/28/2026
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0236 PM CDT Thu May 28 2026
Valid 291200Z - 301200Z
...Colorado Plateau and Southwest...
Dry and breezy conditions are expected across portions of the CO
Plateau and Southwest as an upper-level trough across the Great
Basin accelerates northeastward through the day. Limited cloud cover
will reinforce efficient mixing of a dry boundary layer with minimum
RH falling to between 15 and 20% (locally 10%) by mid afternoon.
Southwest winds of 15-25 mph, low RH and receptive fuels will
support several hours of elevated fire weather conditions Friday,
with a slight eastward expansion of Elevated highlights warranted
based on latest forecast guidance and expected drier fine fuels.
..Williams.. 05/28/2026
.PREV DISCUSSION... /ISSUED 1248 AM CDT Thu May 28 2026/
...Synopsis...
An upper-level low over the Great Basin will translate into an open
wave as persistent ridging continues across the central CONUS. A
compact upper low will move out of southern Quebec into New England
on Friday night, transporting ample moisture and a southward
progressing cold front. Fire weather concerns are expected to remain
limited to the eastern Great Basin and Southwest as the upper-level
trough advances northward.
...Great Basin and Southwest...
Dry, southerly flow is expected to continue into Day 2/Friday as
upper level troughing lifts over the region. At peak heating, RH
reductions to 15-20% and south-southwesterly winds of 15-25 mph are
expected to promote Elevated fire weather conditions across the
eastern Great Basin, Colorado Plateau, and portions of the
Southwest. A 50-60 kt mid-level jet will emerge at the base of the
lifting trough, supporting a narrow region of locally critical fire
weather conditions in terrain-favored areas of the Four Corners
where wind gusts of up to 35 mph and less than 15% RH may coalesce.
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0412 PM CDT Thu May 28 2026
Valid 301200Z - 051200Z
...Synopsis...
An upper trough pushes northeastward into the Northern Rockies by
early next week as blocking ridge remains over the central U.S.
Surface high pressure and associated dry conditions amid light winds
will dominate over the Great Lakes and Midwest while troughing
across the Northeast. Much of the Plains and Southeast will continue
to see good opportunities for showers and thunderstorms with deeper
boundary layer moisture in place, keeping fire weather concerns low.
The exiting upper-level trough into the Northern Rockies will
promote a gradual warming and drying trend across much of the
Intermountain West and Southwest through the middle of next week.
Diffuse surface pressure gradients will keep winds on the light side
with above normal temperatures and dry conditions supporting drying
and curing of fuels. Longer term model guidance suggests intrusion
of deeper atmospheric moisture into southern AZ and NM, west of the
Divide, as early as Tuesday as weak troughing sets up over Baja
California. However predictability remains low which precludes
introduction of dry thunderstorm probabilities at this time.
..Williams.. 05/28/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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