RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Thu May 28 17:21:03 UTC 2026.
No Mesoscale Discussions are in effect as of Thu May 28 17:21:03 UTC 2026.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Thu May 28 2026
Valid 281300Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR WESTERN IDAHO
INTO CENTRAL AND EASTERN PORTIONS OF OREGON AND WASHINGTON...
...SUMMARY...
Scattered severe thunderstorms are possible over western Idaho and
east of the Cascades in Washington and Oregon. Severe gusts (60-85
mph), large hail, and perhaps a tornado are the forecast hazards
this afternoon through the late evening.
...Columbia Basin vicinity into ID/northern NV...
A mid- to upper-level low over the Sierra Nevada will move little
during the period. Water-vapor imagery this morning indicates a
disturbance over NV will move north and northwestward through
eastern NV into eastern OR by early evening. In the low levels, an
area of low pressure is forecast to develop by late afternoon and
migrate from the ID/OR border into the Columbia Basin.
A plume of steep 700-500 mb lapse rates arc around the northern
periphery of the western U.S. low and extend from the Snake Valley
westward into OR/WA. As heating of a seasonably moist airmass
occurs, initial thunderstorm activity will gradually shift from
south to north from northern NV/southern ID and southern OR. Model
forecast soundings show steep low to mid tropospheric lapse rates
favorable for evaporative cooling and the development of strong to
severe downdrafts. Slightly greater buoyancy is shown in model
guidance farther north in northern OR into western ID (1500 J/kg
MLCAPE). As storms move into this region during the late afternoon
to evening timeframe, it is possible a more extensive threat for
severe gusts develops. Regardless, severe outflow both with the
stronger cores and linearly oriented clusters appear to be the main
hazard. Large hail may accompany the stronger cells. A continued
threat for scattered severe gusts may occur into the late evening as
this activity shifts northward into interior portions of WA.
...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.
..Smith/Weinman.. 05/28/2026
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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1108 AM CDT Thu May 28 2026
Valid 281630Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FROM WESTERN IDAHO INTO WESTERN AND CENTRAL
WASHINGTON/OREGON....
...SUMMARY...
Scattered severe thunderstorms are 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.
...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.
..Hart/Lyons.. 05/28/2026
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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
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Thu May 28 2026
Valid 281700Z - 291200Z
No changes were made to the existing Day 1 fire weather outlook. The
forecast remains on track, please see previous discussion for
additional details.
..Williams.. 05/28/2026
.PREV DISCUSSION... /ISSUED 1247 AM CDT Thu May 28 2026/
...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.
...Please see www.spc.noaa.gov/fire for graphic product...
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