SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0631 AM CST Fri Nov 06 2020

Valid 061300Z - 071200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected across the U.S. mainland.

...Synopsis/Discussion...
In mid/upper levels, a reasonably high-amplitude synoptic pattern
will prevail over the CONUS.  From west-east:  a strong trough is
initially evident in moisture-channel imagery offshore from the
Pacific Northwest and northwestern CA, with an embedded 500-mb low
west of the OR coast.  The associated cyclone is forecast to dig
south-southeastward approximately along the northern CA coast
through the period, crossing the SFO Bay Area overnight before
pivoting inland toward the Central Valley.  Strong height falls and
cooling aloft are expected over the suitably moist coastal/offshore
marine layer ahead of the low.  Associated mostly shallow convection
may deepen enough on an isolated basis to produce near-shore
lightning.

Elsewhere, synoptic ridging prevails from northern MX to the Corn
Belt.  To its south and southeast, a broad, weak, cut-off, mid/upper
cyclone is located over much of AR, east TX, LA, the Delta region,
and the northwestern Gulf, with the circulation currently centered
near Toledo Bend Reservoir.  Through 12Z tomorrow, this feature is
progged to meander erratically and slowly near its present position,
orbited by mesoscale vorticity lobes, while gradually broadening and
weakening.  Associated negatively tilted 500-mb troughing may start
to link with the height weakness accompanying what now is T.D. Eta
over the northwestern Caribbean, near the end of this period, or on
day-2.  Divergence aloft over a moist and minimally inhibited Gulf
air mass may support isolated thunderstorms from the Gulf reaching
parts of the coast near southeastern LA.  Isolated thunderstorms
over the relatively high-theta-e air of the Gulf Stream also may
reach portions of the Atlantic coast from the Carolinas southward,
and across south Florida.

..Edwards/Kerr.. 11/06/2020

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