LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Wed May 10 2023
Valid 101200Z - 111200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE HIGH PLAINS...
...SUMMARY...
Scattered severe thunderstorms capable of producing large to very
large hail, severe/damaging winds, and potentially a few tornadoes
should occur this afternoon and evening, centered over parts of the
central High Plains.
...High Plains...
An upper trough over the western states will progress eastward
today, with meridional/southerly flow at mid/upper levels becoming
established over much of the High Plains by late this afternoon and
evening. At the surface, low-level moisture will continue to stream
northward over much of the Great Plains, and to the east of a
dryline forecast to mix eastward over the High Plains through the
day. A zone of low-level easterly/upslope flow is expected to
persist, centered on northeastern CO into eastern WY and the NE
Panhandle vicinity.
As large-scale ascent preceding the upper trough overspreads the
Rockies and adjacent High Plains, initially high-based convection
should develop over the higher terrain and spread
north-northeastward this afternoon and evening. Isolated strong to
severe winds may occur with the initial activity, but large hail
should be an increasing concern once thunderstorms intercept greater
low-level moisture across the High Plains. A corridor of very large
hail potential is evident across parts of northeastern CO into
northwestern KS and parts of southwestern NE. Across this area,
favorable deep-layer shear should support supercells. Ample
low-level shear should also support a threat for a few tornadoes
over this same region if convection can remain at least
semi-discrete through the early evening. There is still some
uncertainty with how many supercells will develop, and how quickly
the mode may transition to more linear clusters, with primarily a
damaging wind threat. Overall convective coverage should be more
limited/isolated with southward extent along the dryline into the
southern High Plains.
...Coastal/East Texas into Louisiana...
Beneath upper ridging, a weak mid-level cyclone augmented by a
convectively generated MCV will move slowly north-northeastward
across the ArkLaTex region today. Modestly enhanced low/mid-level
flow associated with these features should encourage some updraft
organization across parts of coastal/southeast TX into LA.
Thunderstorms that develop across this region could become locally
strong to severe, with a threat for isolated damaging winds. A
tornado or two also appears possible, given a favorable/veering
low-level wind profile and some hodograph curvature. However,
widespread cloudiness should tend to mute daytime heating and the
degree of destabilization that can occur. Have therefore maintained
a Marginal Risk, with some northward expansion.
...North Dakota into Northern Minnesota...
A weak shortwave trough will move eastward atop the northern extent
of the upper ridge near the international border through the
afternoon/evening. Latest NAM/RAP forecast soundings indicate steep
midlevel lapse rates will be present, aiding in the development of
weak to moderate instability. Thunderstorms are expected to develop
along a southeastward-advancing front initially over Manitoba and
spread southeast into ND and northern MN. Modestly veering wind
profiles will result in marginal effective shear magnitudes around
20-30 kt, allowing for occasionally organized cells, despite rather
modest low/mid-level flow. Isolated large hail and damaging winds
appear possible with the strongest cores.
..Gleason/Lyons.. 05/10/2023
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