SPC AC 151709

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1209 PM CDT Fri May 15 2020

   Valid 161200Z - 171200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE MID MISSOURI/MISSISSIPI VALLEYS...AND FROM SOUTH/EAST TEXAS TO
   THE ARKLATEX...

   ...SUMMARY...
   At least a few severe thunderstorms may impact parts of eastern and
   southern Texas early Saturday, and over parts of the lower Missouri
   and middle Mississippi Valleys Saturday afternoon and evening.

   ...Synopsis...
   A moist and unstable air mass will remain across the southern and
   central Plains toward the middle and lower MS Valley on Saturday,
   with a shortwave trough affecting the northern Plains and an upper
   low over TX. A surface low associated with the northern trough will
   develop over NE and deepen a bit as it pivots northeast into WI,
   with a diffuse boundary extending southwest into west TX.

   Scattered storms, and possible areas of widespread precipitation,
   are expected to be ongoing early Saturday ahead of the upper wave
   into the mid MO/upper MS Valleys where warm advection will exist,
   and in association with residual storms and/or outflows from TX
   toward the lower MS Valley. While the severe threat does not appear
   particularly widespread, isolated severe storms are expected
   throughout the period.

   ...Mid MO/MS Valleys...
   An unstable air mass will gradually develop in the warm advection
   zone ahead of the surface low, from KS/MO into IA and western IL.
   Models indicate 500-1000 J/kg MLCAPE is possible south of the
   developing warm front. This boundary should extend from the low
   across central IA and into northern IL by late afternoon. Veering
   winds with height will produce large SRH values near and north of
   the warm front, conditionally favoring supercells or even a brief
   tornado. Degree of destabilization is uncertain and will depend on
   antecedent rain, heating and advection. Otherwise, shear farther
   south into KS and MO appears less favorable, but still sufficient
   for isolated severe storms.

   ...South/East TX toward the Arklatex...
   Numerous storms, possibly with an MCS, are likely to be ongoing over
   much of east/southeast TX early Saturday, with at least isolated
   damaging wind potential. Given the tendency for outflows to move
   faster than forecast by the models, predictability in terms of
   location is low. If enough of an unstable air mass remains ahead of
   the early storms, a Slight Risk for wind could be needed. In
   addition to that threat, additional storms may develop where pockets
   of instability remain, perhaps over Deep South TX where stronger
   instability is possible barring early day scouring, and in
   association with the upper low as it drifts east toward the
   Arklatex. Weak shear suggests disorganized storm modes for this
   activity, with localized hail or wind threat.

   ..Jewell.. 05/15/2020

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z