San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
SPC AC 141730
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CST Sat Jan 14 2017
Valid 151200Z - 161200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST AND CENTRAL TEXAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...
A severe threat with large hail, isolated wind damage, and possibly
a tornado may occur Sunday across parts of the southern Plains.
A mid/upper-level low with embedded 70+ kt mid-level speed maximum
will move northeastward Sunday from southern AZ/NM and adjacent
northern Mexico to the southern High Plains. A southerly to
southeasterly low-level jet will likewise shift eastward across West
and central TX through the day, as low-level moisture returns
northward across the southern Plains. At the surface, an area of
weak low pressure associated with the mid/upper-level low over
northern Mexico should develop northeastward into eastern NM and the
TX Panhandle by Sunday evening, and eventually consolidate over OK
by the end of the period. A cold front attendant to this low will
advance eastward across West and central TX through the day. A
shallow, cold airmass over much of the central/southern Plains will
likely undergo only slow modification across the southern Plains.
The northward extent of sufficient low-level moisture return to
support surface-based convection remains unclear per 12Z NAM/GFS
guidance. Better low-level moisture characterized by mainly mid 50s
to lower 60s surface dewpoints will remain confined along/south of a
remnant front lifting slowly northward as a warm front across the
southern Plains through Sunday evening, with some disagreement
amongst model guidance on the placement of this boundary across
north TX into southern OK. Regardless, there will likely be
surface-based thunderstorm development across the warm sector in
West TX by early Sunday afternoon along and south of the warm front.
With modest daytime heating and a sufficiently moist low-level
airmass, MLCAPE of 500-1000 J/kg seems probable to develop in the
warm sector Sunday afternoon ahead of the eastward-advancing cold
front. Veering and strengthening winds with height supporting
effective bulk shear values of 40-50 kt per various forecast
soundings suggest any thunderstorms that develop along/ahead of the
front will be able to acquire organization, and pose a threat for
isolated large hail/damaging winds, and perhaps a tornado.
Thunderstorms should eventually consolidate into a line along the
cold front, with mainly a damaging wind threat continuing into
Sunday evening across central TX. This wind threat should eventually
wane across central TX by late Sunday evening as convective
inhibition increases and thunderstorms become mainly elevated. Along
and north of the warm front that should be located across north
TX/southern OK, marginal elevated instability may exist in
combination with sufficient mid-level speed shear to support an
isolated hail threat, perhaps as far north as southwestern OK.
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