Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 231623
SWOMCD
SPC MCD 231622
GAZ000-FLZ000-ALZ000-231745-

Mesoscale Discussion 0815
NWS Storm Prediction Center Norman OK
1122 AM CDT Tue May 23 2017

Areas affected...Portions of northern Florida and southern Georgia

Concerning...Tornado Watch 257...

Valid 231622Z - 231745Z

The severe weather threat for Tornado Watch 257 continues.

SUMMARY...Strong to occasionally severe thunderstorms will continue
east/northeastward across Watch 257 through the early afternoon,
with an attendant threat for a couple tornadoes and damaging wind
gusts.

DISCUSSION...Along and ahead of a line of thunderstorms (near the
AL/GA border as of 16 UTC/12 EDT), pockets of heating have brought
surface temperatures into the mid/upper 70s and low 80s. In turn,
with rich boundary-layer moisture present, mixed-layer CAPE values
have risen to upwards of 1000 J/kg, based on forecast and modified
observed sounding data. Radar/lightning observations have indicated
a gradual upward trend in intensity over the last hour, and storms
should persist in this relatively favorable thermodynamic
environment for several hours.

Deep-layer shear profiles remain favorable for occasional
low/mid-level rotation, as a southwesterly low-level jet crosses the
region and winds veer with height from the surface to mid levels.
Recent KVAX and KTLH VWP data depict the presence of approximately
150-200 m2/s2 of 0-1km storm-relative helicity, suggesting
occasional low-level mesocyclogenesis potential (either
line-embedded or in semi-discrete cells). Indeed, a dual-pol
tornadic debris signature was observed in southern Randolph County,
Georgia around 1545-1555 UTC, confirming this environmental
potential. As such, a threat for damaging winds and a couple
tornadoes will persist as storms spread east across Watch 257 this
afternoon.

..Picca.. 05/23/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CHS...JAX...FFC...TAE...

LAT...LON   31868481 32368339 32638263 32518217 31918228 30918273
            30458304 30148410 30118510 30388573 31418521 31868481




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