SPC 0830Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0132 AM CST Sun Dec 13 2020

Valid 151200Z - 161200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for thunderstorms appears negligible across the U.S.,
Tuesday through Tuesday night.

...Discussion...
Models indicate that initially amplified mid/upper troughing digging
to the lee of the southern Rockies by 12Z Tuesday may undergo
considerable shearing during this period.  The primary embedded
short wave perturbation, perhaps including at least a transient
closed mid-level low, is generally forecast to pivot across the
central and southern Great Plains, through the middle and lower
Mississippi Valley by the end of the period.  As it does, it is
forecast to provide support for slowly deepening surface troughing
across and east of the Mississippi Valley.  Although initially
expansive cold surface ridging across and east of this region at the
outset of the period will suppress significant surface cyclogenesis,
this may include the development of a surface low over the lower
Ohio Valley by 12Z Wednesday.  Otherwise, a frontal zone, initially
extending across the central Florida Peninsula into the northern
Gulf of Mexico, probably will become the primary focus for potential
cyclogenesis.  And models indicate a couple of waves developing
along it by late Tuesday night.  

Boundary-layer moistening and destabilization within the warm sector
of one of these, across the north central into northeastern Gulf of
Mexico, could provide support for increasing thunderstorm activity
(well offshore) Tuesday night.  Another wave, developing a bit
later, may be accompanied by at least increasing boundary-layer
destabilization off the south Atlantic coast.

Otherwise, across and inland of coastal areas, through most of the
U.S., generally stable conditions are likely to prevail with
negligible risk for thunderstorms.

..Kerr.. 12/13/2020

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