630
ACUS01 KWNS 161232
SWODY1
SPC AC 161230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Wed Jul 16 2025

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST/GREAT LAKES AND CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered strong to severe thunderstorms are possible this afternoon
and evening from parts of the central High Plains to the Great Lakes
and Mid-Atlantic.

...Midwest/Great Lakes...
A well-defined MCV is evident on radar/satellite imagery this
morning over IA. This feature will drift east-northeastward today
across the Midwest and Great Lakes, eventually reaching southern
Ontario tonight. A related surface low will develop from IA to
southern WI and Lake Michigan this afternoon/evening, with the
primary synoptic front farther north in WI. Diurnal heating of a
rather moist low-level airmass will likely yield around 1000-2500
J/kg of MLCAPE across southern WI into northern/central IL (locally
stronger with southward extent). The modestly enhanced low/mid-level
winds associated with the MCV should support around 30-40 kt of
deep-layer shear, sufficient for organized severe thunderstorms.

Current expectations are for a band of semi-discrete thunderstorms
to develop across eastern IA into northern IL and southern/central
WI by early to mid afternoon as large-scale ascent attendant to the
MCV overspreads the destabilizing warm sector. Some of this activity
could be supercellular initially and pose a threat for isolated
severe hail along with damaging winds. With time late this afternoon
and evening, gradual upscale growth into a bowing cluster should
occur, with a greater risk for severe/damaging winds towards Lake
Michigan and parts of southern Lower MI. Although low-level flow and
related shear is not forecast to become overly strong this
afternoon, it should be sufficient for some low-level updraft
rotation and perhaps a few tornadoes, particularly across parts of
southern WI/northern IL where semi-discrete convection may occur.

...Ohio Valley/Mid-Atlantic...
A weak mid-level shortwave trough located over the OH Valley this
morning will advance northeastward today to the northern
Mid-Atlantic/NY. Recent visible satellite imagery this morning shows
considerable cloud cover present with this feature, along with some
low clouds downstream. Even so, filtered daytime heating of a
seasonably moist airmass should support the development of weak to
locally moderate instability by this afternoon. Poor lapse rates
aloft may tend to inhibit stronger updrafts to some extent, but
marginal deep-layer shear (generally around 20-30 kt) should still
support some degree of convective organization. Loosely organized
clusters and occasional cells may pose an isolated threat for
damaging winds as they spread generally east-northeastward across
parts of the OH Valley and Mid-Atlantic this afternoon/evening.
Confidence in a more concentrated corridor of damaging winds remains
too low to include greater severe probabilities at this time.

...Central Plains to Northern Missouri...
A convectively reinforced surface front should stall by this
afternoon across KS into eastern CO, with a modest low-level upslope
flow regime occurring across the Front Range/central High Plains. On
the southern periphery of an upper trough moving eastward over the
northern/central Plains, thunderstorms should develop by early
afternoon over the higher terrain of the central Rockies. This
convection is forecast to move eastward into the adjacent High
Plains through the rest of the afternoon, and continuing through the
evening. The post-frontal airmass should only modestly destabilize,
but enough instability and the presence of steepened lapse rates
aloft are forecast to support robust updrafts. Weak low-level flow
veering to westerly and gradually strengthening with height at
mid/upper levels will likely foster around 35-45 kt of deep-layer
shear. This will easily support supercells and associated large hail
threat with the initial development. Some potential for upscale
growth into a loosely organized cluster is possible across southeast
CO and vicinity this evening along/near the stalled surface front.
If this occurs, then severe winds would become the primary risk.

Farther east across KS into northern MO, isolated convection may
develop through peak afternoon heating along the front. While
deep-layer shear is forecast to remain fairly modest, strong
instability and steep mid-level lapse rates could still support
occasional severe hail/wind with the more robust cores that can be
sustained. Additional convection may develop along/north of the
front this evening in a low-level warm advection regime, while also
posing an isolated severe threat.

...Central Gulf Coast...
Convection offshore from the central Gulf Coast remains disorganized
this morning, as a weak surface low (Invest 93L) remains along/near
the coast of the FL Panhandle. Regardless of potential tropical
development (reference latest NHC forecast), modest enhancement to
the low-level wind field should occur as this feature tracks towards
coastal/southeast LA by early Thursday morning. Thunderstorms should
occasionally spread inland along/near the central Gulf Coast through
the period, but overall severe potential still appears too limited
to introduce a Marginal Risk with this update.

..Gleason/Bentley.. 07/16/2025

$$