- Day Three
acus02 kwns 180601
Storm Prediction Center ac 180600
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
0100 am CDT sun Mar 18 2018
Valid 191200z - 201200z
..there is an enhanced risk of severe thunderstorms across middle
Tennessee...northern Alabama...and far northwest Georgia...
..there is a slight risk of severe thunderstorms from Tennessee
southeastward into Georgia and northern Florida...
..there is a marginal risk of severe thunderstorms across much of
Tornadoes, damaging wind and hail are expected across parts of
middle Tennessee, much of northern Alabama, and northwest Georgia. A
strong tornado or two is possible during the late afternoon. Severe
wind is also possible into northern Florida.
A compact shortwave trough will move quickly from Arkansas Monday morning
to the Tennessee Valley by 00z Tuesday, with a slight deamplification. Wind
profiles will increase throughout the day, with cooling aloft
overspreading KY, TN, and northern al/GA. At the surface, low
pressure will move from OK across TN, with a cold front extending
from middle Tennessee across central MS by 00z Tuesday. Ahead of the front,
dewpoints into the lower 60s f will reach as far north as TN, with
mid 60s f over Alabama and Georgia. To the east, a warm front will lift across
northern Alabama and Georgia during the day, allowing for destabilization.
Severe thunderstorms are likely near the surface low and along the
cold front, with the primary threat area from middle Tennessee into
northern Alabama and northwest Georgia during the afternoon.
..middle Tennessee into northern Alabama and northwest Georgia...
Scattered showers and a few thunderstorms may be ongoing Monday
morning from Tennessee into northern Georgia associated with warm advection near
the warm front. This activity should lift north, allowing for
heating farther upstream across western Tennessee and MS. If early day
storms are more widespread than expected, this could have an impact
on the position of the main threat area later in the day.
A minor capping inversion will be present around 850 mb according to
forecast soundings. This will keep the warm sector free of
additional precipitation contamination. Lapse rates aloft will
steepen as the shortwave trough approaches, and wind profiles will
strengthen creating a favorable setup for tornadic supercells. The
area of strongest lift, shear and instability will exist over a
relatively limited in area, but supercells that do occur will have
significant tornado potential, along with large hail. The eastern
extent will be limited by a wedge of cooler air from eastern Tennessee
across northern Georgia. Storm density will likely decrease across north
central al, farther away from the main area of lift, but a
conditional threat of supercells capable of a tornado or two and
large hail will exist. This threat may spread across eastern Alabama into
western Georgia during the evening, as warmer air spreads east resulting
in surface based instability.
..FL Panhandle into southern Georgia...
Although well removed from the shortwave trough to the north, a
broad belt of strong flow aloft will encompass the southeast, with
deep-layer shear profiles favorable for severe storms. Mid to upper
60s f dewpoints will result in favorable thermodynamics to support
strong to severe storms. Storms are expected to form over the Florida
Panhandle into northern Florida by early to mid afternoon, spreading into
southern Georgia. Although low-level shear is not particularly strong, it
may be sufficient to support a tornado or two, with the primary risk
being damaging winds.