SPC AC 141255

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0655 AM CST Sun Feb 14 2021

   Valid 141300Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
   CENTRAL AND NORTHERN FLORIDA...

   ...SUMMARY...
   Damaging to severe gusts are possible within episodes of
   thunderstorms today over central and northern Florida, along with a
   slight threat for tornadoes.

   ...Synopsis...
   In mid/upper levels, broadly cyclonic flow will continue across much
   of the central CONUS and MX, on either side of a progressive
   synoptic trough.  The trough was located at 12Z from western CO
   south-southwestward across eastern AZ and the central/northern Gulf
   of California.  By 12Z tomorrow, this trough should extend across
   central KS, southwestern OK, west-central TX, and north-central to
   west-central MX.  Downstream, a broad fetch of southwesterly flow
   will cover most of the eastern CONUS, Gulf of Mexico and FL. 
   Several minor vorticity lobes/maxima will eject northeastward within
   that belt, across the Gulf and Southeast.

   The two most prominent embedded shortwave troughs were apparent in
   moisture-channel imagery near the FL West Coast and over the west-
   central Gulf.  This feature will proceed northeastward to the
   Atlantic over the next several hours and deamplify.  Meanwhile, the
   upstream perturbation should eject northeastward across the central/
   northern Gulf as a weakening, negatively tilted perturbation,
   reaching southern portions of MS/AL and northwestern FL by 00Z, then
   accelerating northeast and essentially dissipating overnight.

   At the surface, somewhat wavy, quasistationary front extended
   east-northeast to west-southwest across north-central FL, then to a
   frontal-wave low over the north-central Gulf south of the
   Mississippi River mouth, then well offshore from BRO.  Over FL, this
   boundary may move slightly northward as a warm front today as the
   surface low approaches, then once the low is past Fl by mid/late
   afternoon, the front should move little or just slightly southward
   again.  This evening, ahead of the major trough aloft, a stronger
   frontal-wave low will form over the Gulf east of BRO, and ripple
   northeastward along the front to shelf waters south of ARA or HUM by
   12Z.

   ...FL...
   South of the front, an outflow boundary that had been drawn across
   central FL near a PIE-DAB line has been diffused by convection that
   since has crossed FL on both sides of the boundary.  Large-scale
   ascent ahead of the leading perturbation has been contributing to a
   favorable environment for showers and mostly non-severe
   thunderstorms all night into early this morning over FL, except for
   a briefly tornadic supercell near PIE around 06Z, along the southern
   boundary.

   Near-surface airmass recovery -- driven both by warm advection and
   muted diurnal surface heating under cloud cover -- is expected
   across central and parts of northern FL behind the morning
   convection.  Associated destabilization will combine with a
   moisture-rich low-level profile south of the synoptic front to
   offset modest midlevel lapse rates, enabling deep buoyancy.

   Severe potential with the next round(s) of convection, from midday
   through afternoon, will decrease with southward extent due to weaker
   deep shear and low-level shear, and with northern extent past the
   front into unsuitably stable near-surface conditions.  The corridor
   of most-favorable parameter spaces still appears to be across parts
   of central and north-central FL.  Weak MLCINH and MLCAPE around
   1000-1500 J/kg should develop.  Patches of 150-250 J/kg effective
   SRH will support a few supercells and small bows embedded in an
   otherwise rather messy convective pattern.  Activity should diminish
   this evening and overnight due to a combination of slow surface
   stabilization and lack of robust support aloft, southeast of the
   weakening mid/upper perturbation.

   ..Edwards/Smith.. 02/14/2021

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