Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Tue Sep 16 2025
Valid 161200Z - 171200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF
NE/CO/KS...
...SUMMARY...
Scattered severe thunderstorms are possible this afternoon into
early evening across a portion of the central Great Plains. Large
hail, severe gusts, and a tornado or two may occur.
...NE/KS/CO...
An elongated, positive-tilt shortwave trough will effectively drift
eastward, pivoting across WY, as multiple embedded impulses rotate
through it during the period. A confined belt of moderate flow
should be centered from the eastern Great Basin to western SD this
afternoon. Much of this will lag to the west of the large buoyancy
plume from the NE/KS/CO border area northeast to the Upper Midwest.
Isolated elevated storms may increase/intensify towards midday
across the NE Panhandle. Scattered to eventually widespread
surface-based storms are expected through the afternoon, both along
the diurnally sharpening front and in the post-frontal environment
emanating off the CO Rockies/Front Range. Rather steep mid-level
lapse rates will be supportive of large hail. But the modest
deep-layer shear along the front and early upscale growth to linear
clusters should modulate hail magnitudes. Linear clustering appears
most probable over southwest NE, which should support a
short-duration uptick in severe wind potential. While most guidance
indicates a strengthening low-level jet into early/mid evening, the
lack of stronger mid/upper-level winds should foster a waning severe
threat after dusk.
...Eastern SD to northeast MN...
Mid-level flow will be weak across most of the Upper Midwest, except
across northeast MN. This area will remain on the peripheral
influence of multiple shortwave impulses over south-central Canada.
Low-level convergence should be weak until early evening, with
convective coverage appearing isolated northeast of eastern SD.
Still, the lobe of steep lapse rates emanating northeast from the
central High Plains will support a swath of moderate to large
MLCAPE. Any sustained storms along the weak front should pose an
isolated threat for severe hail and damaging winds.
...VA Tidewater and far northeast NC...
A weak cyclone east of the Outer Banks is progged to drift
northwestward towards the NC/VA border area by this afternoon.
Low-level flow enhancement to its northwest will promote potential
for strong to marginally severe gusts with any sustained convection
near the cyclone core. However, the airmass over land should remain
thermodynamically limited. Surface winds shifting from the north to
northeast will be necessary for the advection of near-70 F surface
dew points, supportive of meager surface-based instability. This may
only glance the coast later this morning into early afternoon before
low-level wind fields subside and the severe risk becomes
negligible.
..Grams/Squitieri.. 09/16/2025
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