136
ACUS01 KWNS 041944
SWODY1
SPC AC 041942

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0242 PM CDT Fri Jul 04 2025

Valid 042000Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN NORTH
DAKOTA INTO NORTHERN MINNESOTA...

...SUMMARY...
Scattered severe thunderstorms are possible later today into the
evening over the Upper Midwest.  Severe gusts will be the primary
hazard.  Isolated severe gusts and hail may also occur from eastern
Oregon into portions of the northern Great Basin/Rockies and the
Central High Plains.

...20z Update...
Minor adjustments were made to the Marginal Risk in Colorado to add
low end hail probabilities. Cells are expected to form and move off
the high terrain into the lower plains through the
afternoon/evening. A few cells may be capable of severe hail, given
sufficient CAPE and deep layer shear. For more information, see
MCD#1562.

The most favorable region for severe storms continues to be the
central High Plains into the upper Mississippi Valley. Storms have
started to develop across this region and coverage is expected to
increase into the evening. Storms will have the potential for
damaging wind and large hail. See MCD#1560 for more information.

..Thornton.. 07/04/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Jul 04 2025/

...Central High Plains into the Upper MS Valley...
Recent satellite imagery shows expansive upper ridging from the
Lower MS Valley into western Ontario, with several disturbances
along the periphery of this ridge. The shortwave trough currently
moving through the central Rockies/central High Plains will be the
most impactful for today`s severe potential as it continues
northeastward towards the very moist airmass in place across the
northern/central Plains and Upper Midwest. Current surface
observations reveal a large reservoir of dewpoints greater than 68
deg F across the northern/central Plains, with higher dewpoints (70+
deg F) farther northeastward across the Upper MS Valley. Strong
heating is anticipated over the region, particularly the Upper
Midwest, destabilizing the airmass by the early afternoon and
contributing to strong to very strong buoyancy.

Low-level convergence along a southeastward-progressing cold front,
as well as along expected pre-frontal troughing, will augment
large-scale ascent provided by the approaching shortwave. All of
this lift will provide the impetus for convective initiation.
Initial development appears most likely in the early afternoon (i.e.
around 18Z) over northeast/eastern CO, NE Panhandle/western NE, and
western KS. Vertical shear and buoyancy will be modest in this
region, limiting storm strength and organization. Even so, steep
low-level lapse rates and moderately high cloud bases could result
in a few strong gusts. A relatively greater severe potential exists
farther north over the eastern Dakotas into northern/central MN.
Here, strong buoyancy (i.e. 2500-3500 J/kg of MLCAPE) is expected by
the late afternoon. Vertical shear will be relatively modest, but
the strong buoyancy should support robust updrafts capable of
precipitation loading and water-loaded downbursts. Given the limited
shear and progressive cold front, a quick transition to an
outflow-dominant, linear structure is anticipated. A few stronger
gusts are possible within this line as well. Isolated large hail
could occur with the strongest, early-stage cellular storms.

...Eastern Oregon into the Northern Great Basin/Rockies...
Extensive cloud cover has begun to clear from south to north as a
lead shortwave trough progresses through the region. Secondary
shortwave trough currently moving through northern CA is expected to
progress eastward/northeastward into the region later this
afternoon, fostering additional storm development this afternoon.
Buoyancy will be modest, but moderate mid-level flow (i.e. 40-45 kt
at 500 mb) will persist, supporting the potential for a few
stronger/more organized updrafts. A locally greater severe wind risk
may materialize across southern ID and northern UT where stronger
heating and deeper mixing is anticipated.

$$