LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1155 PM CST Mon Jan 09 2023
Valid 101200Z - 111200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL/SOUTHERN CA...PARTS OF SOUTHEAST NV...NORTHWEST
AZ...SOUTHWEST UT...
...SUMMARY...
Isolated strong to severe thunderstorms capable of producing
damaging winds and perhaps a brief tornado may occur today across
parts of southern/central California. Thunderstorms capable of
isolated severe gusts will also be possible across parts of
southeast Nevada, northwest Arizona, and southwest Utah.
...California Coast into the Sacramento/San Joaquin Valleys...
A strongly forced convective line is expected to move onshore across
parts of the central/northern CA coast just before the start of the
forecast period (12Z this morning), in conjunction with an intense
deep-layer cyclone over the eastern Pacific. Despite meager
instability, strong low-level and deep-layer flow/shear will support
a threat of locally damaging gusts and perhaps a brief tornado as
this line moves onshore and eventually spreads into portions of the
Sacramento and San Joaquin Valleys. Some weakening of this
convective line is expected with time as the primary cyclone begins
to occlude, but cooling temperatures aloft and steepening midlevel
lapse rates may support a few stronger cells or line segments within
a post-frontal regime through the day, with enough residual
flow/shear to support a continued threat of locally strong/damaging
gusts. The stronger post-frontal convection may also produce small
hail, but buoyancy appears too limited to support a severe-hail risk
at this time.
...Parts of the Southern Great Basin...
As the occluding cyclone lifts northward near the OR/northern CA
coast, the southern portion of the primary mid/upper-level shortwave
trough will continue to progress eastward across southern CA and
eventually into the southern Great Basin by late afternoon. A weak
surface low may develop in the lee of the Sierras in association
with this shortwave trough and attendant cold front. Modest diurnal
heating will support some weak destabilization along/ahead of the
front across portions of the Great Basin, with redevelopment of a
convective frontal band possible during the afternoon. While storm
intensity will generally be limited by weak buoyancy, rather strong
low/midlevel flow and modest steepening of low-level lapse rates
will support some threat of locally severe gusts as convection
spreads from southeast NV into northwest AZ and southwest UT.
..Dean/Supinie/Squitieri.. 01/10/2023
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