Well damn!!!
000
FXUS62 KFFC 180835
AFDFFC Area Forecast Discussion
National Weather Service Peachtree City GA
435 AM EDT Sun Mar 18 2018
As vigorous shortwave moves east over TN valley, broad and
unusually strong westerly flow to the south remains in place. In
my experience with severe weather forecasts both here and in the
southern plains, this pattern has a great deal of potential to
produce atypically high instability and very strong deep vertical
wind shear with supercells the dominant mode. It has been over a
year since this area has seen supercell storms of this magnitude
(Jan 22 2017). Large hail and a few tornadoes will be likely.
Given MLCAPE values 2000-2500 J/kg and 0-6km bulk shear of
60-70kts, hail will likely be much larger than the Jan 2017 event
with sizes of 2 to 3 inches likely. If there is a bright side to
this story, it could be the low level shear, 0-1km bulk shear is
only progged of 30-35kts. This is still quite strong and should be
sufficient for a few tornadoes, but unlikely to see the larger
/long-tracked tornadoes that we saw with the Jan 2017 event or
other notable supercell-based tornado events and outbreaks.
Interestingly, CIPS top 15 analogs based on 00Z NAM valid 00Z Tue
do not contain any events in the last 10 years, so could be some
analogs with lower storm report density and thus lower analog
probabilities. Top analogs is Apr 3 1998 which produced widespread hail over north GA but other dates have hit or miss coverage of
reports and not too many tornado events though there area some.
Other bright side of supercell events is that coverage/probability
of any point seeing severe storms will be lower than with linear
events. Not something you want to take a chance on however, plan
accordingly. Have kept PoPs closer to guidance and perhaps lower
with mainly 40-60pct Monday afternoon and evening.
Will certainly keep a close watch on this and will continue with
steady pace of impact briefings.