ACUS01 KWNS 161247
SWODY1
SPC AC 161246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Fri May 16 2025

Valid 161300Z - 171200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF EAST-CENTRAL AND SOUTHEAST MISSOURI...WESTERN AND CENTRAL
KENTUCKY...SOUTHERN ILLINOIS AND INDIANA...SOUTHWEST
OHIO...NORTHWEST TENNESSEE...AND NORTHEAST ARKANSAS...

...SUMMARY...
A regional outbreak of severe thunderstorms is likely this afternoon
into tonight across parts of the mid Mississippi, Ohio and Tennessee
Valleys. This will include intense supercells associated with
tornadoes, large hail and wind damage. Several strong tornadoes are
expected, and a long-track high-end tornado will be possible. From
the evening into the overnight, a bowing line segment is expected to
form with potential for tornadoes and damaging winds, some possibly
greater than 75 mph.

...Mid Mississippi and Ohio Valley/Tennessee Valley Region...
As an upper-level low near the MN/ND border shifts east today, a
mid-level jet streak will move from the Plains into the
mid-Mississippi Valley. A surface cold front will move east across
the Great Lakes, Midwest and OH/TN Valley region this afternoon and
tonight. An expansive warm/moist sector will destabilize during the
day, setting the stage for a regional severe weather outbreak this
afternoon and tonight.

Scattered severe thunderstorms, with a history of large hail, were
ongoing at 13z from northeast AR into eastern KY. Clusters of severe
storms, including supercells, will continue moving northeast within
this corridor through at least early afternoon. The eventual
longevity of these storms remains uncertain, however downstream
diurnal destabilization could allow storms with a severe hail/wind
threat to move into WV/western VA this afternoon.

In the wake of these morning storms, destabilization will occur as a
warm front lifts north, with strong instability (MLCAPE in excess of
2500 J/kg) developing from portions of eastern MO east into the
OH/TN Valley region, and south in advance of the front into eastern
TX. The presence of strong mid-level flow will contribute to
deep-layer shear averaging 50 kts or higher across a large area.

Vigorous redevelopment of severe storms is expected by early
afternoon across southern/eastern MO as height falls overspread the
area. More isolated development is expected southward along the cold
front towards 00Z. Initial storm development will strongly favor
supercell storm mode with all severe hazards possible, including the
potential for strong tornadoes across the Moderate/Enhanced Risk
areas where low-level shear will be strongest. Large to very large
hail will also be possible with mature supercells this afternoon
through early evening. As storms continue moving east across the
OH/TN Valley region, eventual upscale growth into multiple bowing
segments is expected. The tornado threat will continue, especially
with QLCS circulations, and significant severe gusts will also be possible.

...Ark-La-Tex/Lower Mississippi Valley...
Warm mid-level temperatures will tend to delay thunderstorm
initiation along the southward-trailing cold front into northeast TX
until later in the day, however at least isolated development is
expected towards 22z-00z. MLCAPE in excess of 3000 J/kg and 45-55
kts of deep-layer shear oriented favorably relative to the front
suggests a supercell mode with large to very large hail, along with
damaging gusts. Although weaker low-level shear will be present in
this area, some potential for a tornado will exist with any mature
supercell. With time, storms may increase in coverage and begin to
cluster in an environment favorable for a continued severe wind/hail threat.

...Portions of the Mid-Atlantic/northern DelMarVa Peninsula...
As the southern portion of the long-lived MCS over PA/NY continues
moving east/southeast today, the potential will exist for
re-development of organized storms, including supercells, over
portions of southeast PA/southern NJ and the northern DelMarVa
peninsula. With moderate west/northwest flow in place to the east of
the upper level ridge, RAP/HRRR forecast soundings depict sufficient
deep shear and moderate instability for a severe hail and wind risk.
Some consideration was given for higher severe probabilities in this
area, however uncertainty remains on the location of a corridor of
greater risk.

..Bunting/Marsh.. 05/16/2025

$$
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ACUS01 KWNS 171259
SWODY1
SPC AC 171258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 AM CDT Tue Jun 17 2025

Valid 171300Z - 181200Z

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

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

...Central/Southern Plains into the Lower/Mid Missouri Valley...
A small but intense bow echo that moved south-southeastward across
parts of KS overnight should continue to weaken this morning across
northeast OK. But in the short term, an isolated threat for severe
winds may continue until the cluster fully dissipates. Across
eastern CO, occasional severe hail may occur with marginal
supercells for another hour or two before additional weakening
occurs. The net effect of this overnight/early morning convection on
the severe potential across the southern/central Plains remains
uncertain. But, a trailing outflow boundary from the decaying MCS
now in northeast OK may prove instrumental in focusing significant
severe potential this afternoon/evening.

A subtle mid-level shortwave trough over the eastern Great Basin and
central Rockies will continue to move eastward over the adjacent central/southern High Plains by this evening. At the surface,
further deepening of a low over southeast CO is anticipated through
the day, with this low forecast to develop into the TX Panhandle by
early evening. A lee trough/dryline will extend southward from this
low, while a convectively reinforced boundary should extend
somewhere along/near the KS/OK border by mid to late afternoon, and
potentially northeastward into eastern KS as well. The airmass
across east-central CO into western KS was generally not
convectively overturned yesterday into early this morning, with the
12Z sounding from DDC still showing around 2800 J/kg of MUCAPE available.

Convective development and evolution remain uncertain later today.
Still, it appears likely that initially high-based thunderstorms
will develop over the higher terrain of central CO this afternoon,
and then spread east-southeastward over the adjacent High Plains
through the evening. Much of eastern CO and vicinity will be in a
post-frontal regime. But steep mid-level lapse rates and sufficient
low-level moisture should support the development of moderate
instability. Strong deep-layer shear should foster supercells
initially, with associated threat for mainly large to isolated very
large hail. Some upscale growth may eventually occur with this
activity as it spreads into western KS this evening, along with an
increased threat for severe/damaging winds.

Farther east into central/eastern KS and MO, severe potential
remains highly uncertain, with a myriad of possible solutions
offered by various high-resolution guidance. In general, current
expectations are for an increasing threat for numerous to
potentially widespread severe/damaging winds across parts of KS into
northern OK, with one or more intense clusters potentially
developing in tandem with a strengthening low-level jet this evening
across the southern/central Plains. Significant severe gusts of 75+
mph remain possible, along with a few tornadoes with any sustained
supercells along/near the boundary this evening as low-level shear
strengthens. Overall, severe probabilities have been expanded
southward some across the OK/TX Panhandles and northern/central OK,
in an attempt to account for where the outflow boundary/front may be
present this afternoon/evening. Additional adjustments to risk areas
are likely with later outlook updates pending additional
observational and model data.

...Mid-Atlantic into the Tennessee Valley/Southeast...
Diurnal heating of a seasonally moist low-level airmass will occur
today across the central Appalachians/southern Mid-Atlantic within a
modestly sheared environment. Thunderstorms are expected to develop
over higher terrain by early afternoon, and subsequently spread
eastward through the evening. Some of this activity may form into
loosely organized clusters. Occasional strong/damaging winds should
be the main severe threat with this activity, particularly across
parts of VA/MD where stronger instability is forecast.

Farther south into the TN Valley/Southeast, a weak mid/upper-level
trough with multiple embedded perturbations should advance slowly
eastward through the day. Similar to yesterday, daytime heating of a
moist airmass should foster moderate to locally strong instability
this afternoon. Around 25-30 kt of mid-level southwesterly flow and
similar values of deep-layer shear should support some loose
convective organization with multiple thunderstorm clusters that can
develop. Have expanded the Marginal Risk for isolated damaging winds southwestward to account for this potential.

..Gleason/Kerr.. 06/17/2025

$$
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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.

$$
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