SPC 1300Z Day 1 Outlook

Day 1 Outlook Image

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

Valid 141300Z - 151200Z


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

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

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

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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