SPC 0700Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1100 PM CST Mon Feb 22 2021

Valid 241200Z - 251200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Aside from a small portion of the Colorado Plateau into adjacent
upper Rio Grande River vicinity, the risk for thunderstorms appears
negligible across much of the U.S., Wednesday through Wednesday
night.

...Discussion...
In the wake of a vigorous short wave impulse progressing around its
northeastern periphery, models indicate that blocking mid-level
ridging across the southern mid-latitude eastern Pacific will expand
and build further through this period.  This is forecast to occur in
phase with substantial amplification of large-scale ridging within
the westerlies across the Aleutians through much of the northeastern
Pacific by 12Z Thursday.

As the short wave trough approaches the British Columbia and Pacific
Northwest coast, it appears that a developing split in the
westerlies inland will begin to become more pronounced.  Downstream 
short wave ridging is expected to overspread the Canadian Rockies
and Prairies within the developing northern branch.  Farther east,
large-scale mid-level troughing is forecast to evolve across the
eastern Canadian Provinces and adjacent portions of the U.S., with
at least one embedded short wave trough accompanied by a modest
surface cyclone across the Great Lakes through New England.

At the same time, as a vigorous short wave trough continues to dig
within the developing southern branch, across the Great Basin into
the Southwest, downstream mid-level flow likely will become
increasingly confluent east of the Rockies into the Ohio Valley. 
Beneath this regime, expansive cold surface ridging is forecast to
build Wednesday night.  As it does, a cold front trailing the
cyclone will sharpen while advancing through much of central Texas,
the lower Mississippi and Tennessee Valleys and Mid Atlantic Coast
states by 12Z Thursday.

Meanwhile, beneath modest/flat subtropical ridging, centered over
the southern Gulf of Mexico and Caribbean, boundary-layer moistening
will continue across the western and northwestern Gulf of Mexico,
with a light southerly return flow allowing for modest moistening
inland of the northwestern Gulf coast.

...Texas...
Moistening inland of the northwestern Gulf of Mexico through this
period is expected to occur beneath a warm and dry lower/mid
tropospheric layer which will provide strong capping.  Although some
NAM forecast soundings across parts of central Texas continue to
suggest that thermodynamic profiles could come close to thunderstorm
development, with lift and destabilization above the southward
advancing cold front late Wednesday night, probabilities for
thunderstorms still appear less than 10 percent at this time.

...Colorado Plateau vicinity...
Despite generally cool/cold thermodynamic profiles, models continue
to suggest that the boundary layer may be warm enough to support
some convection capable of producing lightning Wednesday afternoon
and evening, aided considerably by strong mid-level cooling and lift
associated with the digging southern branch impulse.

..Kerr.. 02/23/2021

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