385
ACUS01 KWNS 172001
SWODY1
SPC AC 172000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Tue Jun 17 2025

Valid 172000Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS...

...SUMMARY...
Severe thunderstorms producing numerous to widespread damaging
winds, scattered large hail (isolated 2+ inches), and a few
tornadoes are expected this afternoon and evening across parts of
the central/southern Plains. The greatest threat for destructive
gusts up to 70-100 mph is forecast across portions of southern
Kansas and northern Oklahoma.

...20z Update Southern Plains...
A convective reinforced outflow boundary across west-central KS
continues to slowly push southward across southwest portions of the
state to near the OK border. This boundary will likely serve as the
focus for robust convective development this afternoon and evening,
as indicated by elevated development farther east. To the north of
the primary surface heating, this initial activity may quickly grow
upscale into one or more clusters before spreading southeast and
becoming more surface-based with time. Large to very large hail,
damaging gusts and some tornado risk are likely with these storms.

Across northwest OK, and the northeastern TX Panhandle, additional,
more isolated storms are likely this afternoon along the southern
most modified outflow and pseudo-triple point area. Surface obs and
18z AMA/LMN RAOBs show substantial low-level shear, large buoyancy
and favorable deep-layer shear for supercells capable of very large
hail and a few tornadoes across northern OK and far southern KS.
Current expectations are still that initially cellular convection
will rapidly develop and pose a severe risk through the afternoon,
before growing upscale as it interacts with additional storms over
KS this evening. One or more organized bows/clusters, capable of
very strong damaging gusts, hail and a couple of tornadoes are
likely this evening. Will maintain the MDT risk with minimal
trimming on the northwest side near the advancing outflow.

...Southeast to the Mid Atlantic...
Several clusters of strong to occasional severe storms are ongoing
and expected to continue this afternoon/evening. Moderate buoyancy
within a very moist air mass could support occasional damaging gusts
from heavily water-loaded downdrafts. Some degree of organization
into loose clusters could continue, especially across AL where
storms have shown slightly stronger cold pools. However, the overall
potential for storm organization is low with vertical shear
remaining quite weak. The severe risk should begin to weaken through
the early evening. Some minor trimming was made to the severe
probabilities along the western edge of the MRGL.

...Rockies...
Scattered severe storms, including a few supercells, will continue
this afternoon. Confidence is highest in the severe threat remaining
near the I-25 corridor where more substantial heating has taken
place. Hail remains the primary risk, though a few damaging gusts
and a brief tornado remain possible.

..Lyons.. 06/17/2025

.PREV DISCUSSION... /ISSUED 1118 AM CDT Tue Jun 17 2025/

...KS/OK...
Overnight and morning thunderstorm activity has significantly
changed the overall forecast for severe storms across the central
Plains for today.  A severe MCS overspread parts of southeast KS and
northeast OK a few hours ago, pushing an outflow boundary southward
into central OK.  Strong heating is occurring to the north of this
boundary, where rapid destabilization is expected this afternoon
across northern OK/southern KS.  A consensus of 12z model guidance
shows this to be the corridor of rapid and intense thunderstorm
development.  Forecast soundings show substantial low-level shear,
steep lapse rates, and sufficient winds aloft for supercells capable
of very large hail and a few tornadoes.  Relatively warm
temperatures in the 850-700mb layer are a negative factor for a
greater tornado concern.  Through the evening, congealing outflows
will likely result in a larger MCS posing a risk of widespread
damaging wind gusts into northeast OK and perhaps parts of northwest
AR/southwest MO.

...Eastern CO/Southeast WY...
Overnight storms also impacted the forecast for this region today.
Easterly low-level winds (enhanced by outflow) have transported
moisture westward into the foothills, where rapid thunderstorm
development is expected by early afternoon.  Steep mid-level lapse
rates and seasonably cool mid-level temperatures, coupled with
sufficiently strong westerly flow aloft, will promote a risk of very
large hail in the strongest storms.  A tornado or two is also
possible.  It is unclear how far east this activity can make it into
the adjacent Plains, where persistent low-clouds and more stable
conditions will likely prevail.  Refer to MCD #1330 for further
details.

$$