SPC AC 131736

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1136 AM CST Mon Feb 13 2017

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
   SOUTHEASTERN TX...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN TX
   INTO WESTERN LA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR SOUTHEAST
   LA ACROSS COASTAL MS/AL AND THE FL PANHANDLE...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TX
   ACROSS THE CNTRL GULF COAST...

   ...SUMMARY...
   Strong to severe thunderstorms are expected to develop from central
   into eastern Texas and perhaps western Louisiana throughout the day
   on Tuesday, with a few tornadoes and damaging winds expected. A more
   conditional threat of isolated severe storms will also exist Tuesday
   night into Wednesday morning from the mouth of the Mississippi river
   toward the coastal Florida panhandle.

   ...Synopsis...
   A shortwave trough will move eastward across TX and toward the lower
   MS valley on Tuesday, losing amplitude overnight and becoming more
   zonal. At the surface, low pressure will deepen across east TX ahead
   of a cold front, with warm front lifting northward ahead of the low
   track. Substantial moisture will be available to support severe
   storms as dewpoints rise into the mid to upper 60s beneath cooling
   temperatures aloft. Strengthening shear profiles with 60 kt
   southwesterly midlevel flow atop a 40-50 kt southerly low level jet
   will support the possibility of damaging storms mainly during the
   day, including the threat for tornadoes.

   ...Central and eastern Texas toward the Sabine river...
   Substantial low-level moisture is already in place today from the
   central TX coast into Deep South Texas, and this air mass will
   spread northward on Tuesday ahead of the developing surface low and
   cold front. Environmentally, models indicate strong low-level shear
   developing with 0-3 km SRH in the 300-400 m2/s2 range, which is very
   supportive of supercells given the moist air mass and adequate
   instability. Hodographs look most favorable over east central into
   southeast Texas between 15Z-21Z, before the low-level jet veers as
   the shortwave passes to the north.

   As for storm evolution, scattered storms are forecast to be ongoing
   along the cold front over central TX at the beginning of the period.
   Some of these storms may contain a hail or wind risk, but the threat
   should increase further by late morning mainly east of the I-35
   corridor. By 15Z-18Z, a marked uptick in storm strength is expected,
   with storms both just ahead of and along the cold front. In both
   cases, supercells are expected initially, with a threat of
   tornadoes. The threat might transition to damaging winds during the
   late afternoon and with northward extent, as the cold front and
   outflows result in merged storms and instability wanes.

   Any discrete supercells will have a threat of tornadoes in this
   environment. Mitigating factors to tornado longevity may be some
   weakness in wind fields around 700 mb especially in southern areas,
   and potential for numerous storm interactions. However, a strong
   tornado or two cannot be ruled out.

   ...Southeast Louisiana, coastal MS and AL and the far western FL
   Panhandle...
   Flow aloft will become quite strong Tuesday night into Wednesday
   morning as the shortwave trough deamplifies. However, gradual height
   falls/cooling aloft will persist, and a warm front will be located
   from southeast LA eastward along or just off the coast. Lift via
   warm advection is likely to result in a few storms over the northern
   Gulf, perhaps affecting the coast. Models insist on far southeastern
   LA as the main threat area, but a few also show storms as far east
   as the western FL panhandle by 12Z Wednesday. Thus, will maintain a
   conditional Slight risk, for these areas for tornado/wind potential.

   ..Jewell.. 02/13/2017

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