Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0748 AM CDT Fri May 15 2026

Valid 151300Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
IOWA...

...SUMMARY...
Severe thunderstorms capable of producing severe/damaging winds and
large to very large hail are likely late this afternoon and evening
across much of Iowa and vicinity. Isolated to scattered severe hail
and damaging winds are possible over a broader area from parts of
the southern High Plains to the Upper Midwest.

...Central Plains into the Upper Midwest...
Generally zonal/westerly mid-level flow will persist over the
northern tier of the U.S. today, with an upper trough/low moving
slowly eastward over central Canada. At the surface, the primary low
will remain in northern Ontario, with a trailing cold front
extending southward into the Upper Midwest and northern/central
Plains. A secondary surface low will likely exist over southwest
KS/northwest OK by peak afternoon heating. A dryline will extend
southward from this low across much of the southern High Plains.

Current expectations are for robust thunderstorm development along
the cold front/surface trough from eastern NE into IA to be delayed
until late afternoon or early evening (around 22-00Z), as
large-scale ascent will remain weak until a low-amplitude shortwave
trough embedded within the westerly mid-level flow eventually
overspreads the surface warm sector. Continued low-level warm/moist
advection through the day and diurnal heating will contribute to the
development of moderate to locally strong instability across this
region by early evening. While low-level winds are forecast to
remain fairly modest, enhanced mid/upper-level flow will support
sufficient deep-layer shear for updraft organization.

Initial supercells should pose a threat for large to isolated very
large hail (2+ inches in diameter), before likely quick upscale
growth this evening across IA supports a risk for mainly scattered
severe/damaging winds. Some of these gusts could exceed 75 mph on a
localized basis given the expectation for an organized cluster and
ample instability. A tornado or two could also occur this evening as
low-level shear gradually increases with a strengthening low-level
jet. Some adjustments have been made to the Slight and Enhanced Risk
areas based on latest observational trends and short-term guidance.
Namely, the Slight Risk has been extended northward into parts of
southeast MN/southwest WI, where some risk for hail-producing
supercells should exist along/ahead of the front. The Enhanced Risk
has also been expanded to include more of western IA, as multiple
supercells may form and eventually congeal into one or more bowing
clusters through the evening.

...Southern High Plains...
Robust daytime heating will yield a very well-mixed/deep boundary
layer near/south of the secondary surface low over southwest KS and
vicinity. Mid-level temperatures will remain cool enough to support
at least weak instability, even with modest low-level
moisture/surface dewpoints. A weak mid-level shortwave trough moving
from the southern Rockies into the southern High Plains will enhance
large-scale ascent late in the day. This should support the
development of high-based thunderstorms, with occasional strong to
severe wind gusts expected. Isolated gusts of 75+ mph may occur
given the very deeply mixed boundary layer extending up to around
500 mb. Cells that develop in west/southwest TX may contain marginal
hail, with elongated hodographs in mid/upper levels.

..Gleason/Bentley.. 05/15/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1129 AM CDT Fri May 15 2026

Valid 151630Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS IOWA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MIDWEST AND CENTRAL/SOUTHERN PLAINS...

...SUMMARY...
Severe thunderstorms capable of producing severe/damaging winds and
large to very large hail are likely late this afternoon and evening
centered across much of Iowa. Isolated to scattered severe hail and
damaging winds are possible over a broader area from parts of the
southern High Plains to the Upper Midwest.

...Central Plains into the Upper Midwest including Iowa...
A cyclonically influenced moderately strong belt of westerlies will
exist over the northern Plains to Upper Midwest and upper Great
Lakes. The primary surface low will remain in northern Ontario, with
a trailing cold front extending southward into the Upper Midwest and
northern/central Plains. A secondary surface low will exist across
southwest Kansas and northwest Oklahoma around peak afternoon
heating, with a dryline extending south-southwestward from this low
across much of the southern High Plains.

Continued expectations are for robust thunderstorm development along
the cold front/surface trough from eastern Nebraska into Iowa to be
delayed until late afternoon or early evening (around 22-00Z), as
large-scale ascent will remain weak until a low-amplitude shortwave
trough embedded within the westerly mid-level flow eventually
overspreads the surface warm sector. Continued low-level warm/moist
advection through the day and diurnal heating will contribute to the
development of moderate to locally strong instability (2500+ J/kg
MLCAPE) across this region by early evening. While low-level winds
are forecast to remain fairly modest, enhanced mid/upper-level flow
will support sufficient (35-50 kt) deep-layer shear for updraft
organization.

Initial supercells should pose a threat for large to isolated very
large hail (2+ inches in diameter), before likely quick upscale
growth this evening across Iowa with an increasing potential for
scattered severe/damaging winds. Some of these gusts could exceed 75
mph on a localized basis given the expectation for an organized
cluster and ample instability. A tornado or two could also occur
this evening as low-level shear gradually increases with a
strengthening low-level jet.

...Southern High Plains...
While clouds linger at midday, particularly with southward extent
across west/southwest Texas, robust daytime heating will yield a
very well-mixed/deep boundary layer near/south of the secondary
surface low over southwest Kansas/northwest Oklahoma. Mid-level
temperatures will remain cool enough to support at least weak
instability, even with modest low-level moisture/surface dewpoints.
A weak mid-level shortwave trough moving from the southern Rockies
into the southern High Plains will enhance large-scale ascent late
in the day. This should support the development of high-based
thunderstorms, with occasional strong to severe wind gusts expected.
Latest short-term guidance suggests a more probable zone of
thunderstorm-related gust potential may focus across the Texas South
Plains and Low Rolling Plains. Isolated gusts of 70+ mph may occur
given the very deeply mixed boundary layer extending up to around
500 mb. Cells that develop in west/southwest Texas may also contain
some hail, with elongated hodographs in mid/upper levels.

..Guyer/Moore.. 05/15/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1102 AM CDT Fri May 15 2026

Valid 151700Z - 161200Z

...CRITICAL FIRE WEATHER AREA FOR SCATTERED DRY THUNDERSTORMS OVER
PORTIONS OF THE SOUTHERN HIGH PLAINS...
...CRITICAL FIRE WEATHER AREA FOR DRY AND WINDY CONDITIONS OVER
PORTIONS OF THE SOUTHERN HIGH PLAINS...
...CRITICAL FIRE WEATHER AREA FOR DRY AND WINDY CONDITIONS OVER
PORTIONS OF THE NORTHERN PLAINS...

The forecast remains on track across much of the CONUS with a
widespread and multi-faceted threat in place across portions of the
plains. The latest forecast guidance this morning shows that
development of convection will expand slightly farther north. As
such, the Isolated Dry Thunder area was extended north across much
of southeast CO. Additionally, the Scattered Dry Thunder area was
also extended to the slightly northward in agreement with the latest
model consensus. While storm motions are slightly slower across this
area (being closer to the center of the mid-level low), precipitable
water values will still struggle to exceed 3/4 of an inch amid
high-based convection.

Morning satellite imagery and surface observations show dry (RHs in
the single digits to teens) and windy (southwest near 10-20 mph)
conditions are already underway over the TX Panhandle and
surrounding areas. As was previously mentioned, convection could
promote localized areas of very strong winds associated with
convection, particularly over portions of the TX Panhandle after
6pm. Similarly, strong westerly surface winds continue to impact
much of the central High and northern Plains this morning before RHs
drop below 20 percent this afternoon in the drawn area.

..Stearns.. 05/15/2026

.PREV DISCUSSION... /ISSUED 0144 AM CDT Fri May 15 2026/

...Synopsis...
Mainly zonal mid-level flow, with multiple embedded impulses, will
prevail over the western and northern CONUS as a low-amplitude
mid-level trough progresses over the southern Plains today. A
surface low will develop over the central Plains and encourage
low-level moisture return east of the I-35 corridor. Meanwhile, dry
downslope flow will usher in behind the surface low and overspread
the southern High Plains. Cold temperatures aloft will overspread
this dry airmass, encouraging high-based dry thunderstorm
development atop receptive fuels, supporting lightning-induced
ignitions over the southern High Plains. Lastly, dry westerly
gradient-induced surface winds are expected across the northern
Plains, driven by a deepening surface low over western Manitoba.
Overall, an active day with relatively widespread wildfire spread
conditions are expected over portions of the Plains states today.  

...Southern High Plains...
To the west of a diffuse dryline, a deep and dry boundary layer will
manifest by afternoon peak heating as downslope flow also
intensifies through the day. Widespread 15+ mph sustained westerly
surface winds are expected during the afternoon, overlapping 10-15
percent RH from southern New Mexico to the Texas Panhandle/Oklahoma
border, warranting Elevated highlights given receptive fuels.
Critical highlights are also in place from southeast New Mexico into
the Texas Rolling Plains, where guidance consensus shows 25+ mph
sustained southwesterly surface winds overlapping RH below 15
percent on a widespread basis for several hours during the
afternoon.

Across the southern High Plains, the approach of a low-amplitude
mid-level impulse will result in seasonably cold mid-level
temperatures overspreading a boundary layer extending up to 500 mb,
yielding classic inverted-v soundings beneath thin CAPE (up to 500
J/kg in some forecast soundings). At least isolated thunderstorm
development is expected along the New Mexico/Texas Panhandle border
initially by mid afternoon. Strong flow aloft will encourage rapid
eastward advancement of these storms, accompanied by erratic wind
gusts. Isolated lightning-induced ignitions are possible with the
onset of storm development. 

However, a greater concern exists for lightning-induced ignitions as
storms progress farther to the east into the Oklahoma Panhandle
toward the Texas Rolling Plains. Here, low-level moisture (while
overall scant for typical deep-moist convection) will gradually
deepen, supporting increased thunderstorm coverage and
intensification. As these storms intensify and produce erratic to
perhaps severe (58+ mph) wind gusts, they will also overspread drier
fuels that have experienced greater than average fuel loading. This
volatile scenario may support several lightning induced ignitions,
followed by potential rapid spread from both the larger scale
gradient winds/gusts, as well as from erratic gusts by strong to
severe thunderstorms, perhaps accompanied by scant precipitation,
warranting the introduction of Scattered dry thunderstorm
highlights. 

...Portions of the Northern Plains...
By afternoon peak heating, the combination of boundary layer mixing
and gradient flow will promote widespread sustained westerly winds
in the 15-25 mph range across portions of the northern Plains. RH
will drop below 20 percent in some spots, warranting broad Elevated
highlights. Critical highlights are in place where guidance
consensus shows the best overlap of 15-20 percent RH and 20-25 mph
sustained westerly surface winds during the afternoon, as well as
where fuels are most receptive to wildfire spread.

...Wyoming and immediate surrounding areas...
Dry downslope flow across portions of the northern Rockies will
support surface winds reaching the 15-20 mph range during the
afternoon, where RH should dip to 15 percent over most locales.
Elevated highlights have been introduced given the presence of dry
fuels. At least some wildfire spread potential exists wherever the
aforementioned meteorological surface conditions can overlap
receptive fuel beds.

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