Severe potential 2/23-2/25

[rolltide_130]

It is looking increasingly likely that areas of the Mississippi Valley will be faced with a significant severe weather threat this coming weekend..

At the surface, a shortwave trough that has increasingly become more amplified with each passing run will dig in and kick across the eastern 3rd of the country, triggering a very strong surface low somewhere in the MO/IA/IL corridor, with a VERY strong low level jet racing northward across the Mississippi Valley..

An unusually potent warm sector for this time of year (aided by the near record temperatures) will allow at least adequate instability to advect northward into the MS Valley region. I'm of the personal opinion that the instability being modeled may be on the low side as of now due to how we have been beating model projections at the surface consistently in this pattern.. However, I still do have some question marks regarding the mid and upper level lapse rates, as they are somewhat mediocre for late February..

Regardless, a substantial severe weather threat may exist this weekend, and it could potentially spread eastward as well with time..

 

[tennessee storm chaser]

i do think we can get a healty warm sector which gfs showing will help make up week lapse rates.... esspecially we can get any cloud breaks... think you meant further east correct than west you said..

 

[Kory]

Valid for Saturday at 6pm. Definitely looking like one of the more healthier threats so far this year.

 

[NWMSGuy]

Valid for Saturday at 6pm. Definitely looking like one of the more healthier threats so far this year.

So would the area highlighted in red be the area of greatest concern for Tornadoes or severe in general?
Northwest MS looks to be in the heart of this specific map.

 

[tennessee storm chaser]

seeing some comparison with the 12 23 15 event.... how the trough is beeing modeled at the mid levels.... and wind fields... associated with it....

 

[rolltide_130]

So would the area highlighted in red be the area of greatest concern for Tornadoes or severe in general?
Northwest MS looks to be in the heart of this specific map.

It highlights the greatest combination of tornado parameters. As of now, this is looking like 12/23/15 in terms of main spatial area in the highest threat (Not opening a can of worms regarding its threat levels though as it's WAY too early to be making that call.. and 12/23/15 had more things going for it than this one appears to have right now..)

 

[tennessee storm chaser]

It highlights the greatest combination of tornado parameters. As of now, this is looking like 12/23/15 in terms of main spatial area in the highest threat (Not opening a can of worms regarding its threat levels though as it's WAY too early to be making that call.. and 12/23/15 had more things going for it than this one appears to have right now..)

tell you one thing it sure does have going for it is.... plenty of low level moisture.... thats big

 

[NWMSGuy]

tell you one thing it sure does have going for it is.... plenty of low level moisture.... thats big

Talk about 12/23 and the one thing that comes to mind is Holly Springs, MS. Man that was nasty.

 

[rolltide_130]

12z models increased the potential some as well.. instability continuing to climb..

Also, the CIPS analogs for 1+ sigtor are moving a little bit further east..

 

[Kory]

One problem that manifested itself during 12/23/15 that doesn't appear to be an issue with this system is mid level height rises.

 

[NWMSGuy]

If I remember correctly I believe Dr. Forbes had issued a Torcon of 9 that day back in ‘15. That could have been an extremely dangerous day if more storms would have materialized even though the Holly Springs storm was dangerous enough.

 

[rolltide_130]

If I remember correctly I believe Dr. Forbes had issued a Torcon of 9 that day back in ‘15. That could have been an extremely dangerous day if more storms would have materialized even though the Holly Springs storm was dangerous enough.

The failure mode there was Forbes (As well as James Spann) incorrectly assumed that the rising heights over AL could be overcome. As we have learned since then, it is almost impossible to overcome rising heights during Dixie setups, regardless of the other parameter space.

 

[tennessee storm chaser]

The failure mode there was Forbes (As well as James Spann) incorrectly assumed that the rising heights over AL could be overcome. As we have learned since then, it is almost impossible to overcome rising heights during Dixie setups, regardless of the other parameter space.

12z euro. Continues to increase threat midssouth Saturday instability keeps creeping up. Interesting

 

[Taylor Campbell]

I hope this isn't a threat that trends west. I'd rather drive the distance to MS or western TN than to AR.

 

[rolltide_130]

CAPE continuing to uptick on the new Euro, and mid and upper temps are trending colder as well. Kinematics have been very strong already for several days, but the thermos are starting to fall into place.. This is starting to get serious, and it's beginning to creep into western Alabama..

 

[tennessee storm chaser]

CAPE continuing to uptick on the new Euro, and mid and upper temps are trending colder as well. Kinematics have been very strong already for several days, but the thermos are starting to fall into place.. This is starting to get serious, and it's beginning to creep into western Alabama..

0z euro was very concerning for. East ark north ms and west. Tenn instability on the rise also more

 

[Daryl]

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 AM CST Thu Feb 22 2018

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
EAST TEXAS INTO THE LOWER MISSISSIPPI...TENNESSEE AND OHIO
VALLEYS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE SOUTHERN PLAINS THROUGH THE OHIO VALLEY AND SOUTHEAST
STATES...

...SUMMARY...
Strong to severe storms will be possible Saturday from a portion of
northeast Texas through the lower Mississippi, Tennessee and Ohio
Valleys.

...Northeast TX into the lower Mississippi Tennessee and Ohio
Valleys...

A significant shortwave trough will eject northeast through the
central Plains and middle to upper MS Valley region Saturday and
Saturday night while taking on a negative tilt. In response to
forcing accompanying this feature, a surface low initially over the
southern Plains will deepen as it develops northeast through the
middle MS Valley, eventually reaching the Great Lakes toward the end
of the period. Warm front extending east from the surface low will
move northward, reaching the OH Valley Saturday night. A cold front
initially across west TX will advance through the Southern Plains
and middle to lower MS Valley during the day reaching the OH and TN
Valleys Saturday night. A strengthening low-level jet resulting from
the deepening cyclone will transport richer gulf moisture northward
with low 60s F dewpoints as far as the OH Valley and mid to upper
60s from east TX to the lower MS Valley. However, instability will
probably remain marginal due to widespread clouds and modest lapse
rates with MLCAPE likely to remain below 1000 J/kg over most of the
warm sector.

A forced line of potentially strong to severe storms should evolve
in vicinity of cold front initially over north central or northeast
TX into southeast OK during the day. Activity will subsequently move
into the lower MS, TN and OH Valley regions as the low-level jet
strengthens to 60+ kt and shifts northeast through moistening warm
sector. Vertical shear and overall character of wind profiles will
be more than adequate for organized severe storms, with potential
for LEWP, bowing segments and a few embedded supercells capable of
damaging wind and a few tornadoes. An upgrade to higher
probabilities might be needed in later outlooks once uncertainties
regarding the thermodynamic environment have been mitigated.

 

[tennessee storm chaser]

On the 0z euro. Surface winds are backed pretty good eastern ark in afternoon. Getting concerned with potential super cellular activity outhead of a potent line.... moving ne from there

 

[rolltide_130]

Saturday moderated itself a little bit on the 12z Euro.. less impressive both thermodynamically and kinematically. If the 0z doesn't pick it back up this system may start to collapse on itself.

 

[Kory]

Saturday moderated itself a little bit on the 12z Euro.. less impressive both thermodynamically and kinematically. If the 0z doesn't pick it back up this system may start to collapse on itself.

Kinematics look about the same to me.