SPC Dec 23, 2024 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0656 PM CST Sun Dec 22 2024

Valid 230100Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.

...Synopsis...
An upper trough currently exists along the coastal Pacific Northwest
this evening, and height rises will occur tonight as the wave moves
northeastward across OR and WA. In the near term, a few
thunderstorms will remain possible over coastal northern CA, and
farther north across western WA beneath the cooler air aloft. Most
of the instability is elevated over southern areas, but weak SBCAPE
may exist near coastal WA. Here, low-level flow will veer to
westerly coincident with the stronger midlevel cooling, supporting
non-severe, low-topped convection.

..Jewell.. 12/23/2024


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SPC Dec 22, 2024 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0159 PM CST Sun Dec 22 2024

Valid 222000Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.

...20Z Update...
Lightning flashes continue to be observed just offshore of the
northern CA coastline as a mid-level trough approaches the Pacific
Northwest. As the mid-level trough continues to advance toward the
coastline later this afternoon and evening, increased mid-level
cooling aloft will encourage at least isolated onshore thunderstorm
development. As such, no changes have been made to the previous
forecast.

..Squitieri.. 12/22/2024

.PREV DISCUSSION... /ISSUED 1003 AM CST Sun Dec 22 2024/

...Northern CA/Pacific Northwest coast through tonight...
Lightning flashes have been observed this morning within a
baroclinic band roughly 150 mi off the northern CA coast, in
association with a midlevel shortwave trough that will move inland
later today into tonight. The potential for isolated lightning
flashes inland will begin this afternoon with elevated convection in
the warm conveyor belt across northwest CA/southwest OR. Other
isolated lightning flashes may also occur this evening into early
tonight along the WA coast as steeper low-midlevel lapse rates and
weak buoyancy spread inland.


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SPC Dec 22, 2024 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0700 AM CST Sun Dec 22 2024

Valid 221300Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.

...Synopsis...
Water-vapor imagery this morning shows an upper trough over the
eastern Pacific to the west of the Pacific Northwest coast. This
upper feature will move east-northeast into British Columbia and
WA/OR tonight. Cooling midlevel temperatures will result in weak
buoyancy (100-200 J/kg MUCAPE) late today into tonight from portions
of northern CA northward along the coastal ranges of OR/WA.
Elsewhere, mainly tranquil and stable conditions will prevail across
the Lower 48 states.

..Smith/Goss.. 12/22/2024


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SPC Dec 22, 2024 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1142 PM CST Sat Dec 21 2024

Valid 221200Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A low chance of general thunderstorms is forecast across parts of
the Pacific Northwest. Severe storms are unlikely.

...Synopsis...
An upper trough will lift out of the eastern states, with a surface
high from New England to the northern Gulf Coast. High pressure will
also exist over much of the Intermountain West, but lower pressure
will affect parts of the West Coast as an upper trough nears.

Cooling aloft will occur through this evening across much of WA, OR,
and northern CA. As midlevel moisture increases, weak elevated
instability may support isolated thunderstorms, primarily after 21Z.
Despite strong shear profiles, such minimal elevated instability is
unlikely to support a severe hail risk.

..Jewell/Weinman.. 12/22/2024


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