318
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

$$