SPC AC 301937

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0137 PM CST Sat Jan 30 2021

   Valid 302000Z - 311200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   NORTHEAST OK INTO SOUTHEAST KS...SOUTHWEST MO AND NORTHWEST AR
   THROUGH EARLY EVENING...

   ...SUMMARY...
   Isolated severe thunderstorms remain possible through early evening
   from northeast Oklahoma into southwest Missouri, as well as parts of
   southeast Kansas and northwest Arkansas.

   ...20z Update - OK/KS/MO/AR...

   The Marginal risk and 10% General Thunderstorm areas have been
   trimmed on the western and southern edges. This adjustments have
   been made based on the current position of the surface low and
   associated cold front and warm front. Additionally, very dry
   midlevel air, noted in water vapor imagery, and as sample by 12z
   regional RAOBs is precluding development of deep convection
   southward along the cold front/dryline. The best chance for strong
   to isolated severe storms will remain near the triple point where
   low level convergence is maximized. Strong ascent will also remain
   focused north/northeast of the surface low, associated with the
   eastward-ejecting shortwave trough. As such, a narrow corridor will
   exist close to the track of the surface low the next few hours from
   far northeast OK/southeast KS into far southwest MO/northwest AR.
   The severe threat should quickly diminish after sunset. For more
   details, reference MCD 44.

   ..Leitman.. 01/30/2021

   .PREV DISCUSSION... /ISSUED 1022 AM CST Sat Jan 30 2021/

   ...OK/KS/MO/AR this afternoon...

   Only minor adjustments have been made to previous forecast with main
   limiting factor being expected very weak buoyancy. A well-defined
   midlevel shortwave trough moving through western OK as of late this
   morning will continue east-northeastward over OK/KS today and MO/AR
   this evening. The associated surface cyclone will likewise develop
   eastward along the KS/OK border, reaching southwest MO this evening.
   Low-level moisture return within the cyclone warm sector remains
   limited by ongoing air mass modification over the Gulf of Mexico in
   the wake of a prior frontal intrusion. However, midlevel moistening
   and lapse rates have been sufficient to support clusters of elevated
   thunderstorms (rooted near 700 mb) this morning in the zone of
   ascent preceding the midlevel trough.

   Ongoing elevated thunderstorms will likely persist from eastern OK,
   southeast KS, and western AR into early afternoon and southwest MO
   through mid afternoon. In the wake of the elevated convection, a
   zone of surface heating along a dryline will overlap a narrow
   corridor of boundary-layer dewpoints of 50-55 F from southeast KS
   across northeast OK, from midday into the afternoon. Destabilization
   in this narrow corridor might become sufficient for surface-based
   convection to develop near and immediately south of the surface
   cyclone. Steep low-midlevel lapse rates and 500 mb temperatures of
   -20 C and colder may support MLCAPE of 250-500 J/kg, with a brief
   window of opportunity for low-topped supercells within the left-exit
   region of the midlevel jet. Isolated damaging gusts and hail, as
   well as an isolated tornado, remain possible this afternoon with
   peak buoyancy, before diminishing rapidly this evening with eastward
   extent and the onset of nocturnal cooling. Given lingering concerns
   regarding destabilization potential, will maintain MRGL category for
   this outlook and continue to monitor for a possible SLGT risk in the
   upcoming 20Z update.

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