208
ACUS01 KWNS 252009
SWODY1
SPC AC 252007

Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0307 PM CDT Sat Jul 25 2026

Valid 252000Z - 261200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
AND EASTERN SOUTH DAKOTA...INTO SOUTHWESTER MINNESOTA AND NORTHWEST
IOWA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
CENTRAL MONTANA...

CORRECTED FOR MISSPELLING

...SUMMARY...
Widespread severe gusts are possible across South Dakota late this
afternoon and into portions of southwestern Minnesota and northwest
Iowa through the evening.

...20 Update Northern Plains/Midwest...
Confidence continues to increase in widespread severe gusts
developing across parts of central and eastern SD late this
afternoon and into the evening. Very hot surface temperatures
(100-110F) are supporting very steep-low and mid-level lapse rates
of 8-9 C/km over western SD. Initial storms developing now with
temperature-dew point spreads of 40-50 F will favor efficient
outflow generation and an increasing potential for severe gusts as
convection develops and intensifies this afternoon.

The primary severe concern across the northern Plains and Midwest
remains the potential for widespread severe wind gusts with one or
more organized convective clusters. A CIG-2 wind area was added for
the potential for some peak gusts in the 80-100 mph range. Some
recent CAM guidance has trended toward more clustering and a compact
bowing cluster across central and eastern SD late this afternoon and
evening. A brief mesovortex tornado or two may also occur if a
bowing cluster can develop. However, weaker overall synoptic forcing
suggests lower confidence in how widespread the most intense storms
will be. See MCD#1729 for short-term information.

Downstream, wind probabilities and CIG-1 have been expanded along a
surface wind shift/buoyancy gradient into parts of northeast NE, IA
and southern MN. Recent HRRR/RRFS time-lagged runs continue to show
a strong cluster moving east and then southeastward this evening and
into the overnight hours. Strong to severe gusts will remain
possible with these storms given the large buoyancy.

Farther north across MN, isolated storms, including supercell
structures could support isolated hail or damaging gusts this
evening.

...MT...
Scattered to widespread high-based storms remain likely this
afternoon and evening over central and southern MT. Steep-lapse
rates in the lowest 3-5 km will support a risk for severe gusts.
Some clustering may occur as storms spread eastward into this
evening. No changes were made to the outlook, see the prior
discussion.

..Lyons.. 07/25/2026

.PREV DISCUSSION... /ISSUED 1137 AM CDT Sat Jul 25 2026/

...SD into adjacent parts of IA/MN...
A prominent upper ridge centered over the central/southern Rockies
will feature the southern periphery of appreciably strong mid to
high-level flow extending from the Pacific Northwest across the
northern High Plains and into the north-central states.  Late
morning surface analysis shows very hot temperatures ensuing across
western NE into the western half of SD with richer moisture (surface
dewpoints in the lower to mid 70s F) located over the eastern half
of NE/SD.  Visible-satellite imagery shows some mid to high clouds
across northern WY moving towards the Black Hills.  This patch of
clouds appears associated with a weak disturbance forecast to move
into western SD later this afternoon.

Downstream across SD, forecast soundings show very steep surface to
500-mb lapse rates developing as temperatures rise into the 100s F.
Expecting initially isolated to widely scattered storms to develop
near the Black Hills, as convective temperatures are breached.
Models show the gradual development of a cluster moving east across
SD early this evening.  Have increased severe-wind probabilities to
account for observational and model-based trends towards an MCS
capable of peak gusts in the 75-90 mph range.  This activity will
probably slowly weaken towards the MN/IA/SD border but perhaps
continue into early overnight with a wind threat.

...MT...
Isolated to scattered storms will likely form near the higher
terrain of southern MT later this afternoon with a gradual increase
in storm coverage as this moves east during the early evening.  A
hot and well-mixed boundary layer will support severe gusts with the
stronger cores and associated outflow.  There is some indication
this activity will cluster and potentially reach parts of
eastern/southeast MT by the late evening.

...Upper Midwest/Upper Great Lakes...
Conditional severe potential exists across parts of the Upper
Midwest spanning Minnesota to Upper Michigan into Wisconsin.  Models
continue to show low storm chances as mid-level heights rise through
the late evening.  Nonetheless, appreciable heating of a seasonably
moist boundary layer will result in strong potential buoyancy later
today into tonight.  Elongated hodographs will support organized
storms capable of a wind/hail threat.  Given a muted diurnal storm
signal in models, the greater chance for isolated storms appears to
be associated with warm advection activity late tonight.

...Northeast NV/northern UT/eastern ID...
Storm development is expected during the afternoon across parts of
northeast Nevada, along the western periphery of the upper ridge.
These storms will spread into adjacent parts of southeast Idaho and
northwest Utah with time.  Isolated severe gusts may accompany the
stronger downdrafts.

...South-central/southeast AZ...
High-based convection is again expected across southeast Arizona
during the afternoon, with initial downburst potential.  A modest
enhancement to easterly flow along the southern periphery of the
upper ridge may allow for localized strong to severe wind gusts to
spread westward into parts of south-central Arizona, before
convection weakens tonight.

$$