SPC 1200Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1124 PM CST Thu Feb 11 2021

Valid 121200Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few weak thunderstorms are possible across parts of the eastern
Gulf and south Atlantic coast region today through tonight, and near
northern California and southern Oregon coastal areas by late
tonight.

...Discussion...
Models indicate little movement to a deep, elongated mid-level low,
centered to the north of the North Dakota/Minnesota border area,
through this period.  And arctic surface high pressure will remain
entrenched across much of North America, to the east of the Rockies.

It does appear that the shallow leading edge of this air mass will
stall across parts of the western through north central Gulf of
Mexico, and the northern Florida/southern Georgia vicinity into the
western Atlantic, as mid-level subtropical ridging begins to build
once again across much of the Southeast.  This is forecast to occur
downstream of a short wave trough turning eastward into the western
Gulf of Mexico, after digging through Mexico.

A significant trailing impulse is forecast to dig near/southwest of
the southern Sierra Nevada, and across the lower Colorado Valley
into northwestern Mexico by 12Z Saturday, as a more vigorous
mid-level perturbation digs toward the Oregon/northern California
coast, downstream of building large-scale mid-level ridging across
the eastern mid-latitude Pacific.  Beneath their respective
mid-level cold pools, thermodynamic profiles may become weakly
unstable and conducive to convection capable of producing lightning
along their tracks, into the Pacific coast and across parts of the
Southwest.  The trailing impulse, with its colder air aloft, has
been accompanied by considerable thunderstorm activity across the
mid-latitude Pacific, and appears to provide the most certain risk
for thunderstorm activity during this period, which could impact
northern California and southern Oregon coastal areas toward 12Z
Saturday.

Meanwhile, east of the Rockies, destabilization supportive of
thunderstorm development appears in the process of becoming
increasingly focused along and south of the surface frontal zone,
and confined to offshore areas of the Gulf of Mexico and western
Atlantic.  This may generally remain the case through much of the
period.  However, a zone of strengthening low-level warm advection
developing across the central through northeastern Gulf of Mexico
may provide a focus for increasing thunderstorm development
impacting northeastern Gulf coastal areas toward 12Z Saturday.

..Kerr.. 02/12/2021

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