And also from this morning's FFC discussion.Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Fri Jun 21 2019
Valid 211200Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN PLAINS SOUTHEASTWARD INTO THE MID
MISSISSIPPI AND TENNESSEE VALLEYS...
Severe thunderstorms are possible today across parts of the northern
and central Plains, southeastward across the Missouri Valley into
the mid Mississippi and Tennessee Valleys.
...Mid Mississippi Valley/Tennessee Valley/Southeast....
A linear MCS in the lower Missouri Valley this morning is forecast
to move east-southeastward into the mid Mississippi Valley. The line
of strong thunderstorms should turn southeastward into lower Ohio
Valley around midday and may reach the Tennessee Valley this
afternoon. The linear MCS is forecast to track southeastward along a
gradient of moderate instability. This combined with moderate
deep-layer shear and steepening low-level lapse rates may be enough
to maintain an isolated wind-damage threat along the leading edge of
the line. Additional strong to severe convection will be possible
along the outflow boundary that is laid out by the MCS across parts
of the mid Mississippi Valley this afternoon. Isolated marginally
severe thunderstorms with strong wind gusts could occur in parts of
the Southeast along low-level convergence zones that heat up
sufficiently near peak heating.
Wonder how much instability we're getting.Saturday could be interesting as well as instability is through the
roof with the cold mid levels continuing. We still need the
forcing and flow suggests more of glancing blow for the local
area. That said, we almost always see an outflow ejected southward
that would also provide the needed lift. Have gone mid range pops
for now but could be some areas to realize likely coverage should
shortwave be further SW. Strong to severe activity with any storms
that develop once again. Heat indices for Sat will approach
critical thresholds over the far SE sections and will need to
monitor closely for possible advisory.
The most the area has seen all year. Models are showing 3500-5000 joules. 3KM NAM, long range HRRR, RAP, GFS, and EURO are all in very good agreement with an MCS impacting the southern app trail region tomorrow. Point soundings across north Georgia from 15z-18z showed a significantly cold mid levels for this time of the year; minus 11 celsius at 500mb, below freezing in the 600-650mb layer, and a good bit of dry air to work with to 750mb.Wonder how much instability we're getting.