Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 161630
SPC AC 161628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1028 AM CST Sat Dec 16 2017

Valid 161630Z - 171200Z


Thunderstorms are possible from parts of south Texas to western
Mississippi, with the possibility of a few strong storms near the
Texas coast tonight.

...Coastal Texas to far Southern Louisiana...
In response to an amplifying/kicker shortwave trough along the CA
coast, a closed upper low over northern Mexico at midday will become
more progressive and eventually take on a more negative tilt as it
accelerates northeastward over the eastern half of TX toward eastern
OK/Ark-La-Tex tonight. Weak near-coastal cyclogenesis is expected
along the middle/upper TX coast this evening with gradual air mass
modification occurring over the western Gulf of Mexico.

As this occurs, convection is likely to increase this evening with
widely scattered thunderstorms spreading northeastward through the
overnight. While deep-layer/low-level shear (accentuated by a 40-55
kt low-level jet) will steadily increase this evening, the
likelihood of a surface-based-convection-conducive air mass remains
questionable over inland areas.

Consistent with late-morning satellite imagery and inland/maritime
observations, latest short-term guidance continues to indicate that
the semi-moisture rich air mass will likely remain just offshore
through tonight. This should limit the potential for surface-based
convection over inland areas with various RAP/12Z NAM forecast
soundings depicting the persistence of a shallow near-surface stable
layer with surface dewpoints generally no higher than 63-64F inland.
While the potential for a tornado and/or damaging winds should
remain very low inland, a few supercells and/or semi-organized bows
may be noted across the offshore waters tonight off the middle/upper
TX coast toward coastal southwest LA.

..Guyer/Dial.. 12/16/2017

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