SPC AC 080459

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1159 PM CDT Sun Oct 07 2018

   Valid 081200Z - 091200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
   WESTERN TEXAS AND FAR SOUTHWEST OKLAHOMA...

   ...SUMMARY...
   Multiple rounds of thunderstorms are expected to develop across the
   southern and central Plains Monday. The greatest chance for severe
   thunderstorms will exist from the Texas South Plains into the Big
   Bend region. A few strong storms are also possible from eastern
   Kansas into into Iowa and southwest Wisconsin.

   ...Synopsis...
   A large, amplified upper trough will exist along the length of the
   Rockies, with an upper ridge centered just off the Mid Atlantic
   coast. Substantial southerly winds will thus exist across the
   Plains, with increasing lift Monday night over the Southern Plains
   as a shortwave trough and midlevel speed max develop into west TX.
   To the north, a leading disturbance is expected to enhance lift from
   the central Plains into the upper Mississippi Valley during the day.


   In the low levels, a surface trough will extend from a weak low near
   the NM/TX border northeastward across IA and into WI. South of this
   front, a very moist air mass will exist, with mid to upper 60s F
   dewpoints common. Multiple bouts of thunderstorms will occur
   throughout the period across much of the Plains, with the most
   likely area of severe weather across western Texas.

   ...Southwest TX into western OK...
   Scattered thunderstorms will be ongoing across parts of the TX
   Panhandle and northwest TX into western OK Monday morning, and
   isolated severe activity cannot be ruled out as little if any
   capping inversion will be present, and shear profiles will be
   sufficient. Additional afternoon storms are likely to form along the
   wind shift near the NM/TX border, and a few supercells will be
   possible as low level winds will veer with height in addition to
   increasing speed shear aloft. Storms will become most numerous after
   00Z, coincident with the stronger lift with the shortwave trough.
   Damaging winds and hail are most likely, but a tornado could occur
   as well as storms form into a linear MCS and approach west-central
   TX by Tuesday morning. Should cellular activity develop ahead of the
   MCS toward the Edwards Plateau, a tornado or two would be possible.

   ...Eastern KS northeastward across IA and into southwest WI...
   Rain and thunderstorms should be ongoing from northeast KS across IA
   into WI, in a zone of low-level warm advection associated with a 40
   kt southwesterly low-level jet. Some northward progression of the
   warm front is expected, allowing destabilization into IA and WI.
   Although existing precipitation may play a role in the effective
   frontal position, at least isolated strong to severe storms are
   possible during the afternoon. Low-level shear will remain favorable
   for storm rotation, and a brief/weak tornado cannot be ruled out.

   ...Southern FL including the Keys...
   TC Michael is forecast to move into the Gulf of Mexico Monday night
   into Tuesday, but will remain well west of FL. Still, relatively
   strong easterlies will develop in the low-levels across the region,
   with bands of thunderstorms expected to affect southern FL. Forecast
   soundings show modest effective SRH values approaching 100 m2/s2,
   suggesting weak rotation is possible in some of the storms. However,
   the severe threat appears low, with weak winds aloft and marginal
   instability.

   ..Jewell/Leitman.. 10/08/2018

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