SPC May 29, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Fri May 29 2026

Valid 291300Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR WEST TEXAS
INTO FAR SOUTHWESTERN OKLAHOMA...

...SUMMARY...
Scattered strong to severe storms capable of sporadic large hail and
scattered severe winds are expected this afternoon and evening
across portions of western Texas. More isolated severe thunderstorms
are likely across parts of the central High Plains, southern Utah,
and the northern Rockies.

...Southern Plains and central High Plains...
Water-vapor imagery shows a mid-level low migrating eastward across
the Mojave Desert towards the southern Great Basin. A 90-kt 250-mb
sub-tropical jet over Baja and Sonora Mexico will progress eastward
into the southern High Plains by this afternoon. The nose of this
speed max will overspread a moist sector east of a dryline where
severe thunderstorm development is forecast later this
afternoon/evening. Farther north, a modestly deepening lee trough
will focus storm initiation over the central High Plains.

Despite some mid and high-level clouds, model guidance shows strong
heating this afternoon and erosion of appreciable convective
inhibition by mid afternoon. A mid-level disturbance implied in
satellite imagery this morning over central NM will move northeast
into western KS and the TX Panhandle by early evening. Scattered
thunderstorms are forecast to develop near the dryline/lee trough.
Forecast hodographs show some elongation across west TX due to the
nose the upper speed max. Have included 15-percent hail
probabilities where supercell development appears greatest [due in
part to more favorable hodographs and within the northern rim of
richer moisture sampled by the 12 UTC Del Rio, TX raob (17.3 g/kg
mean mixing ratio)]. Large hail (1.5 to 2.5 inches in diameter)
will be possible with the supercells. Severe gusts are forecast to
become more prevalent during the evening as mergers and outflow
consolidate into a few linear clusters. Severe gusts of 60-80 mph
are possible as this activity shifts eastward into the Low Rolling
Plains and southwest OK during the evening.

Through the late evening, isentropic ascent near the terminus of the
nocturnal jet may support elevated, loosely organized convection
across portions of northwest OK and western KS. Isolated hail/wind
may accompany the stronger storms over the central High Plains into
central OK where storm coverage will probably remain isolated.

...Northern Rockies/Montana...
Diurnally-driven orographic ascent within the terrain of northern ID
and southwest MT will likely support isolated thunderstorm
development by late afternoon given weak capping and northward
advection of steep mid-level lapse rates. Residual low-level
moisture across north-central MT (dewpoints in the upper 40s to low
50s) coupled with 30-35 knot southerly mid-level flow will likely
promote intensification and some degree of organization (possibly
into transient supercells and/or organized bands) through the early
evening hours. Sporadic large hail and severe gusts appear possible
with the most intense convection as it spreads north towards the
Canadian border.

...Southern Utah...
A few high-based storms developing within a deeply mixed boundary
layer (inverted-V profile) may yield an isolated risk for severe
gusts (60-70 mph).

..Smith/Kerr.. 05/29/2026


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SPC May 29, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1253 AM CDT Fri May 29 2026

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
WESTERN TEXAS...

...SUMMARY...
Scattered strong to severe storms capable of sporadic large hail and
scattered severe winds are expected this afternoon and evening
across portions of western Texas. More isolated severe thunderstorms
are likely across parts of the central High Plains, southern Utah,
and the northern Rockies.

...Synopsis...
Late-evening water-vapor imagery reveals an upper low over central
CA with a subtropic jet emanating out of Baja CA into the southern
Rockies. Over the next 24 hours both of these features will migrate
east/northeast into the central and southern High Plains. Despite
some weakening of the upper wave, 25-35 knot mid-level flow will
overspread the central and southern High Plains where low-level
moisture is gradually increasing within a weak east/southeasterly
flow regime. The combination of modest broad-scale ascent and
strengthening deep-layer shear atop a moistening low-level air mass
should support the potential for a few strong to severe
thunderstorms during and after peak heating from southern TX
northward across the southern Plains and into parts of the central
High Plains.

Elsewhere, orographic ascent within the northern Rockies will
support another day of isolated to widely scattered thunderstorms,
including a few severe storms. A migratory upper trough over the
central CONUS will continue to support scattered, but weak,
thunderstorms across the OH Valley and Southeast states this
afternoon.

...Southern Plains and central High Plains...
Thunderstorm development is expected by mid-afternoon across western
TX into eastern CO along a modestly deepening lee surface trough
where ascent should be focused and mixed-layer inhibition minimized.
Slightly stronger synoptic ascent across the southern High Plains
should promote higher thunderstorm coverage across western TX/TX
Panhandle region with more isolated coverage with northward extent.
15% wind probabilities were introduced across portions of western TX
to reflect the potential for higher storm coverage.

Across both the southern and central High Plains warm low-level
conditions/deep boundary-layer mixing combined with weak flow within
the lowest 1-3 km will likely promote outflow dominant storms with
an attendant threat for severe gusts. Stronger mid-level flow across
western TX may support a more prolonged severe threat, and possibly
a few transient supercells capable of large hail and/or organized
bands capable of gusts upwards of 75 mph. Through the late evening,
isentropic ascent near the terminus of the nocturnal jet may support
elevated, loosely organized convection across portions of northwest
OK and western KS.

...Northern Rockies/Montana...
Diurnally-driven orographic ascent within the terrain of northern ID
and southwest MT will likely support isolated thunderstorm
development by late afternoon given weak capping and northward
advection of steep mid-level lapse rates. Residual low-level
moisture across north-central MT (dewpoints in the upper 40s to low
50s) coupled with 30-35 knot southerly mid-level flow will likely
promote intensification and some degree of organization (possibly
into transient supercells and/or organized bands) through the early
evening hours. Sporadic large hail and severe gusts appear possible
with the most intense convection as it spreads north towards the
Canadian border.

...Southern Utah...
5% wind probabilities were introduced across southern to southeast
UT where weak, high-based convection may support a few strong to
severe dry downbursts. Although latest CAM ensemble guidance depicts
scant buoyancy (MUCAPE between 100-250 J/kg) and very transient
convection, a very deep boundary layer (LCL values upwards of 3 km)
featuring 25-35 knot flow will likely promote sporadic strong to
severe wind gusts.

..Moore/Marsh.. 05/29/2026


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SPC May 29, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


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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SPC May 28, 2026 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... 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.


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