Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS03 KWNS 200619
SPC AC 200618
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
1218 AM CST Fri Jan 20 2017
Valid 221200Z - 231200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN GA AND NORTHERN/CENTRAL FL...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FL
PANHANDLE TO COASTAL NC...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
GULF STATES TO EASTERN NC...
Severe thunderstorms, with damaging winds and perhaps some hail, are
expected across much of the southeastern US Sunday.
Short-range models begin to diverge a bit by Sunday afternoon as the
NAM is considerably faster and farther north with the upper low
center than the GFS/UKMET/Canadian which advance the low into
northern AL. The NAM would suggest a faster and more advanced
squall line into the southeastern states early in the period as
large-scale forcing is substantially east of the other models at
22/12z. Even so, quality boundary-layer air mass resides over the
Gulf basin and this should advance inland easily ahead of stronger
forcing and expected convection.
Severe thunderstorms, in the form of a squall line, may be ongoing
at 22/12z...a continuation of late day2 convection that will be
supported by a strong progressive mid-level speed max on the order
of 110kt. In response to this feature, LLJ will increase over the
northeastern Gulf basin into coastal Carolinas. Associated warm
advection will aid convection as it advances through a well-defined
ascent corridor. Current thinking is a squall line should migrate
across the Gulf states, eventually progressing across the FL
peninsula as flow strengthens from the west. Damaging winds and
perhaps some hail and possibly a few tornadoes can be expected with