Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 221625
SPC MCD 221625
Mesoscale Discussion 0112
NWS Storm Prediction Center Norman OK
1025 AM CST Sun Jan 22 2017
Areas affected...Portions of southern GA...north FL...far southeast
Concerning...Severe potential...Tornado Watch likely
Valid 221625Z - 221800Z
Probability of Watch Issuance...95 percent
SUMMARY...Particularly Dangerous Situation (PDS) Tornado Watch
issuance is forthcoming -- around 1730Z.
DISCUSSION...A dangerous outbreak of tornadoes is expected to occur
across parts of north FL, southern GA, and far southeast AL this
afternoon. Air mass destabilization continues across the eastern
Gulf Coast vicinity ahead of deepening surface low pressure near
Mobile Bay. As the surface low undergoes rapid deepening along its
east-northeastward/northeastward track, markedly strengthening
low-level southerly mass fluxes will occur -- encouraging the
development of moderate buoyancy south of a warm front branching
east of the low.
Present indications are that the ongoing warm-advection shield of
convection from southern AL to GA will continue moving
northward/northeastward, with the precipitation-flanking warm front
to the south advancing northward. As this occurs, surface-based
discrete and semi-discrete supercells will continue to spread
northeastward and east-northeastward into the warm sector --
initially developing along a surface trough/front extending south of
the developing low into the Gulf. The related supercell-tornado risk
will spread inland after 18Z. Very long, curved hodographs yielding
400-600 m2/s2 of effective SRH, combined with MLCAPE around
500-1250 J/kg, will support the potential for long-track,
fast-moving, strong tornadoes.
The issuance of a long-lead-time Particularly Dangerous Situation
Tornado Watch is planned for around 1730Z.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 29888564 31178527 32128373 31958247 31058143 29818150
28928295 29208446 29888564