638
ACUS01 KWNS 100555
SWODY1
SPC AC 100553

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1253 AM CDT Thu Jul 10 2025

Valid 101200Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO TONIGHT ACROSS PARTS OF WESTERN AND CENTRAL
KANSAS...CENTRAL AND EASTERN NEBRASKA...WESTERN IOWA AND PARTS OF
SOUTHEASTERN SOUTH DAKOTA...

...SUMMARY...
Strong thunderstorms posing a risk for severe hail, damaging wind
gusts and perhaps a couple of tornadoes are possible late this
afternoon into tonight across parts of the central Great Plains into
mid Missouri Valley.

...Discussion...
Stronger westerlies will remain confined to the higher latitudes
through this period, with one significant short wave perturbation
forecast to accelerate from eastern portions of the Canadian
Northwest Territories through areas northeast of Hudson Bay,
accompanied by a deepening surface cyclone.  It appears that the
leading edge of cooler, drier air in the wake of this cyclone will
advance south of the international border into the northern Rockies
and through adjacent portions of the northern U.S. Great Plains,
trailed  by another notable mid-level short wave impulse, which
models indicate will dig near/east of the Canadian through northern
U.S. Rockies.  As this occurs, mid-level troughing within weaker
flow in lower latitudes is forecast to slowly dig from the northern
Great Basin toward the central Great Plains, suppressing stronger
ridging in the subtropical to southern mid-latitudes, initially
centered over the Southwest.

This will be preceded by a couple of convectively generated or
augmented perturbations migrating across the mid Missouri Valley and
Upper Midwest, a modest mid-level trough slowly turning
east-northeast of the lower Great Lakes vicinity, and several weak
perturbations progressing through broad, weak cyclonic flow across
the Southeast through southern Atlantic Seaboard.

...Great Plains into Midwest...
Uncertainties remain concerning potential convective evolution
through this period.  Models suggest that surface boundaries may
remain relatively diffuse, but residual seasonably moist
boundary-layer air may become characterized by sizable CAPE with
daytime heating, beneath steep lower/mid-tropospheric lapse rates,
including warm elevated mixed layer air.

There does appear at least a somewhat consistent signal within
various convection allowing guidance that an MCV associated with
ongoing convection across parts of the middle Missouri Valley could
provide a focus for strong thunderstorm development later today
across parts of the Upper Midwest.  Otherwise, in advance of the
digging upstream troughing, models indicate that a modest belt of
southwesterly low-level flow (including 20-30+ kt in the 850-700 mb
layer) will generally persist through the day east of the lee
surface trough, from the Texas Panhandle/South Plains into the
middle Missouri Valley.  It appears that this will coincide with a
corridor of stronger heating/deeper boundary-layer mixing across the
higher plains, where thunderstorm activity initiating during the
late afternoon may pose a risk for damaging wind gusts.

Within the more moist low-level environment across eastern Nebraska
into western Iowa, the wind fields, aided by veering with height,
might become at least marginally conducive to a couple of
supercells, in the presence of sizable CAPE, before forcing for
ascent associated with the approaching mid-level trough tends to
support upscale growing clusters this evening.

...Upper Ohio Valley into portions of New England...
Near the southern periphery of the mid-level troughing shifting east
or east-northeast of the lower Great Lakes region, models indicate
that scattered thunderstorm development is probable during peak
afternoon heating, in the presence of moderate CAPE (1000-2000+
J/kg) and shear enhanced at least somewhat by a belt of 20-30 kt
westerly mid-level flow.  This environment may become conducive to
small hail and potentially damaging wind gusts, before activity
weakens this evening.

...Southeast/Southern Atlantic Seaboard...
Aided by forcing for ascent associated with the mid-level
perturbations, in the presence of weak mid-level inhibition, one or
two upscale growing clusters of storms may overspread the southern
Atlantic Piedmont and coastal plain late this afternoon and evening.
 Forecast soundings indicate that a seasonably moist environment may
become characterized by moderate CAPE, with perhaps a sufficient
degree of sub-saturation to allow for evaporative cooling in
downdrafts to contribute to modest surface cold pool development.
In the presence of weak deep-layer southwesterly mean flow on the
order of 10-15 kt, the potential for development of sufficiently
strong rear inflow to support surface gusts in excess of 50 kt
appears low, but even with peak gusts generally on the order of
35-50 kt, sporadic damage will still be possible.

..Kerr/Weinman.. 07/10/2025

$$