RSS Mesoscale Discussions from Storm Prediction Center
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Wed May 13 2026
Valid 132000Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
GREAT BASIN INTO THE NORTHERN ROCKIES...
...SUMMARY...
Scattered thunderstorms capable of damaging wind gusts remain
possible from the Great Basin into northern Rockies this afternoon
and evening. Other areas of isolated severe wind/hail risk may occur
over the northern Appalachians and the Texas Panhandle.
...20Z Update...
The previous forecast (see below) remains generally on track.
Thunder and severe probabilities were trimmed over the OH Valley to
account for the passage of a broken squall line. Thunder
probabilities were also trimmed over portions of eastern KS and
immediate surrounding areas, as confidence for organized elevated
convection along the easternmost edge of a low-level WAA regime
continues to decrease.
..Squitieri.. 05/13/2026
.PREV DISCUSSION... /ISSUED 1120 AM CDT Wed May 13 2026/
...WV/PA/NY...
Recent surface analysis places a low over northern Lake
Huron/central Ontario, with a cold front extending back
southwestward through western OH and western KY. Current satellite
shows the associated shortwave trough extending from central Ontario
into the Mid MS Valley. This imagery also shows two embedded
vorticity maxima, one near the surface low over central Ontario and
the other farther southwest over IL/IN. This shortwave is expected
to mature throughout the day, trending towards a more neutral tilt
by this evening, while also gradually shifting eastward. The
associated cold front is forecast to shift quickly eastward as well.
At least scattered clouds will likely persist throughout the day,
somewhat tempering the overall daytime heating. Even so, modest
low-level moisture (i.e. dewpoints in the low/mid 50s) ahead of the
cold front will support a corridor of sufficient buoyancy for
thunderstorm development ahead of the front from western PA and WV
eastward across PA and into southern/central NY. Linear forcing
along the front and relatively modest deep-layer shear will favor a
multicellular line segment mode. Potential exists for a few deeper
updrafts capable of damaging gusts, but the limited heating ahead of
the front, modest buoyancy, and displacement south and east of the
stronger low to mid-level flow should keep the overall severe
potential isolated. A few isolated instances of hail are possible
early in the convective cycle before the more linear structures
dominate.
Recently issued MCD #0710 addresses this area as well.
...Great Basin into the northern Rockies...
Current satellite imagery shows a well-defined, negatively tilted
shortwave trough progressing across the Pacific Northwest. This wave
is forecast to continue eastward through ID and MT today. Strong
heating and deep boundary-layer mixing is expected ahead of this
wave from the Great Basin into the northern Rockies. At the same
time, mid-level moisture associated with the wave will advect
eastward/northeastward, resulting in large area of deep inverted-v
thermodynamic profiles that are also buoyant enough to support
convection and isolated lightning. Strong mid-level flow will
accompany the shortwave, with moderate mid-level flow extending
southward from the primary wave through UT and far western CO.
Scattered convection is expected as lift associated with the wave
begins to interact with this destabilizing airmass, likely starting
around 20/21Z from western MT into northern UT. This convection,
which should include lightning-producing updrafts, will then spread
eastward/northeastward with time. Strong to severe gusts are
possible across this entire region, with the highest likelihood for
severe gusts from central/southern ID into central MT where the
strongest mid-level flow is expected.
...TX Panhandle...
Deep boundary-layer mixing is anticipated across the TX Panhandle
today, with temperatures climbing into the 90s. Low-level moisture
advection should result in higher dewpoints across the eastern
Panhandle, with the resultant dryline acting as a focus for
convergence and attempts at convective initiation. The overall
environment does not look conducive for initiation and majority of
the CAMs do not show storm development. However, any storm that can
persist in this environment would conditionally pose a threat of
damaging wind gusts and large hail.
Read more
