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SPC Day 1 Outlook

Updates are issued at 0600 UTC, 1300 UTC, 1630 UTC, 2000 UTC, 0100 UTC - Current UTC time: Feb 23 2018 12:14 pm


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Day 2


Categorical Day 1 Outlook

000
ACUS01 KWNS 230546
SWODY1
SPC AC 230545

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1145 PM CST Thu Feb 22 2018

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MAINLY LATE
TONIGHT ACROSS NORTHERN TEXAS AND ADJACENT PORTIONS OF SOUTHERN
OKLAHOMA...

...SUMMARY...
Strong thunderstorms are possible across northern Texas today
through tonight.  A couple may be accompanied by some risk for
severe hail, particularly late tonight.

...Discussion...
Although some weakening of the high center off the south Atlantic
coast may be underway, subtropical ridging appears likely to remain
prominent across much of the Southeast through this period. 
Upstream, models indicate that a vigorous short wave trough (now
digging near the southern Sierra Nevada) will remain progressive and
maintain considerable strength, pivoting across the Four Corners
region toward the central Plains, as another short wave trough digs
into the Pacific Northwest.  Forcing associated with the lead
impulse may support the initiation of cyclogenesis within a
deepening lee surface trough across the southern High Plains by 12z
Saturday.  There are discrepancies among the models concerning this
process, probably at least in part due to differences in the erosion
of lingering cold surface ridging now present across the southern
Plains.  However, the primary initial surface low probably will form
across parts of southeast Colorado/northeast New Mexico into the
Texas/Oklahoma Panhandle region, while a secondary low forms by late
tonight along a residual frontal zone across northern Texas,
probably across the Texas Big Country.  As this occurs, substantive
boundary layer modification and moistening is expected across much
of southeastern through central Texas.

...Lower Mississippi Valley...
While elevated moisture return continues on southerly return flow
above the residual shallow cold surface-based air mass across much
of the southern Plains, a warm and moist boundary layer air mass is
already present across portions of the upper Texas coast and Sabine
Valley, east northeastward through parts of central and southern
Louisiana.  Models suggest some north/northeastward advection of
this air mass is possible today, with surface heating contributing
to destabilization and potential for scattered afternoon and evening
thunderstorm development across Louisiana and southern/central
Mississippi.  While modest southwesterly mid-level flow (30-40 kt at
500 mb) could enhance convection, low-level flow and hodographs are
expected to remain rather modest in strength.  With thermodynamic
profiles only supporting weak to modest CAPE, severe storm
probabilities still seem less than 5 percent.

...Texas Big Country into the Red River Valley...
Thunderstorm activity may be ongoing or in the process of increasing
in coverage at 12Z this morning, in response to lower/mid
tropospheric warm advection above the cold surface-based air.  In
the presence of modestly steep mid-level lapse rates, some risk for
marginally severe hail may not be out of the question, and could
continue through the day, as periodic scattered thunderstorm
redevelopment remains focused across the region, on the northern
periphery of capping elevated mixed layer air.  Further steepening
of mid-level lapse rates, increasing mid/upper forcing for ascent,
and strengthening deep layer wind fields and shear with the impulse
emerging from the Southwest may contribute to  somewhat better
potential for convection capable of producing severe hail late
tonight (toward 12Z Saturday).

..Kerr/Leitman.. 02/23/2018

$$
        

Day 3

Day 4

Largly based on original scripts from Ken True: saratoga-weather.org and Rick Curly: ricksturf.com