SPC Dec 13, 2024 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0142 PM CST Fri Dec 13 2024

Valid 132000Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely through tonight.

...20Z Update...
The previous forecast reasoning (see below) remains the same, and
only minor changes were made with this update.

..Weinman.. 12/13/2024

.PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/

...Southern/Central Plains into the Ozarks/ArkLaTex...
A compact shortwave trough over the Great Basin this morning will
move eastward across the southern/central Plains through tonight
while gradually amplifying. Related low-level mass response will
encourage the northward advance of modified Gulf moisture across
parts of the southern/central Plains ahead of a weak surface low 
and cold front forecast to track from the central High Plains to
eastern KS/OK by early Saturday morning. Given the limited/shallow
nature of the low-level moisture return, current expectations are
for any convection that develops late tonight in the warm advection
regime to remain elevated. MUCAPE is generally forecast to remain
less than 1000 J/kg, which should tend to limit the prospect for
large hail with these elevated thunderstorms. Even so, cold
mid-level temperatures associated with the ejecting shortwave trough
and sufficient shear through the cloud-bearing layer may support
some risk for small hail with the strongest cores. This activity is
expected to spread eastward from the southern/central Plains into
the Ozarks/ArkLaTex vicinity through the end of the period.

...Northern California...
An upper trough will approach the West Coast late tonight into early
Saturday morning. Associated low-level warm/moist advection will
occur ahead of a weak surface front, with a broad area of
precipitation forecast across parts of northern CA and the Pacific
Northwest. Gradual cooling of mid-level temperatures will occur as
the upper trough approaches, which may support meager MUCAPE across
parts of northern CA for the last few hours of the period (early
Saturday morning). Isolated lightning flashes may occur with
low-topped convection along/near the front, with overall
thunderstorm probabilities around 10 percent.

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