SPC Jan 12, 2017 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0335 AM CST Thu Jan 12 2017

Valid 151200Z - 201200Z

...DISCUSSION...
Models are in good agreement through Sunday/D4 depicting a compact
shortwave trough moving northeastward out of Mexico across West TX
during the day, and continuing in a negatively tilted fashion into
the central Plains by 12Z Monday/D5. At the surface, low pressure
will move from NM into the TX Panhandle during day, continuing into
KS by 12Z Monday. Meanwhile, a warm front will lift northward across
the body of OK, and into southeast KS and MO. While moisture will
spread northward behind the warm front, instability is forecast to
be very weak except along and mainly south of the Red River where
MUCAPE on the order of 500-1000 J/kg is forecast. Forecast soundings
show enlarged low-level hodographs, favorable for rotation with any
storms. Given the rapid advancement of the upper system, a
quasi-linear storm mode appears most likely, with damaging winds and
a few tornadoes possible. As such, an initial 15% slight risk is
warranted. Localized strong winds are also possible into OK, but to
a lesser extent as instability will be very weak, but still with
strong lift. 

For Monday/D5 and beyond, models diverge a bit but the
aforementioned shortwave trough will continue northeastward across
the mid and upper MS Valleys, with cold front trailing southwestward
across the Arklatex into much of eastern TX. Mid to upper 60s
dewpoints will exist ahead of the front, beneath southwesterly
midlevel flow on the order of 40-50 kt. This would suggest a
slow-moving line of thunderstorms, perhaps with some damaging wind
potential, with flow parallel to the boundary. However, the upper
wave will continue to depart the region, MUCAPE looks to be
generally less than 500 J/kg, and the cold front is forecast to
decelerate. Thus, will defer any upgrade to slight risk to later
outlooks when predictability increases.

By Tuesday/D6, another shortwave trough is forecast to move across
northern Mexico and the southern Plains. This feature currently
appears too unpredictable for any additional severe areas, but
whatever boundary is left behind over TX/AR/LA by the D5 system may
eventually serve as another focus for severe on D6 and D7 farther
east along the Gulf Coast.

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