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Severe WX March 3-4, 2020 Severe Weather (Central Tennessee)

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As discussed there looks to be potential for a severe outbreak around mid next week. SPC update:
1582794488217.gif



Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0155 AM CST Thu Feb 27 2020

Valid 011200Z - 061200Z

...DISCUSSION...
Medium-range guidance continues to come into better agreement
regarding the eastward ejection of an upper trough/low from the
Southwest and northern Mexico across the southern/central Plains
from Day 4/Sunday through Day 6/Tuesday. Low-level moisture will
continue to advect northward across the southern Plains and lower MS
Valley in this time frame. The past several runs of the
deterministic ECMWF have been relatively consistent in the timing
and amplitude of the eastward ejection of the upper trough/low.

The potential for substantial low-level moisture return across parts
of east TX into the ArkLaMiss by Day 6/Tuesday has increased. Low
and mid-level flow are also forecast to markedly strengthen across
these areas, particularly Tuesday evening into early Wednesday
morning. With strong forcing for ascent preceding the upper
trough/low, a surface low should deepen as it develops northeastward
from portions of east TX into the vicinity of the Mid-South. A
trailing cold front should also shift eastward across TX into parts
of the lower MS Valley by the end of the Day 6/Tuesday period (early
Wednesday morning).

A thermodynamic and kinematic parameter space favorable for the
formation and maintenance of organized severe thunderstorms will
probably exist over these areas from Tuesday evening though early
Wednesday morning. Storms could form both along and ahead of the
eastward-moving cold front, with all severe hazards possible.
Therefore, a 15% severe delineation has been introduced for Day
6/Tuesday. There is some uncertainty with how far east the threat
will extend into MS late Tuesday night, and adjustments to this 15%
area are likely.

Uncertainty in the placement of both the upper trough/low and
related surface low increases into Day 7/Wednesday. At least some
severe threat may continue across parts of the Southeast (mainly
AL/GA vicinity), but low-level moisture should gradually decrease
with eastward extent. 15% severe probabilities may be needed in a
later outlook issuance over parts of the Southeast on Day
7/Wednesday once the synoptic-scale evolution becomes a bit clearer.

..Gleason.. 02/27/2020”
 

Kory

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Yeah some timing differences still but this is looking more Wednesday for Alabama. A Tuesday/Tuesday night threat for ArkLaMiss. There will be robust lapse rates with this system which is always the first thing I look for...we’re taking 7.0-7.5 C/KM which will lead to strong updrafts.
 

warneagle

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If this Tuesday holds serve, 3 of our last 4 Super Tuesdays will have had severe wx. 2008, 2016 (it was a smaller event but still) and possibly 2020.
Yeah and this one covers some of the same areas as 2008 (although a bit further south for now).
 

Kory

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Yeah and this one covers some of the same areas as 2008 (although a bit further south for now).
This one is gonna be ejecting negative tilt further southeast than 2008. We're still seeing timing fluctuate and I suspect we will continue to see that through the weekend.
 
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Yeah some timing differences still but this is looking more Wednesday for Alabama. A Tuesday/Tuesday night threat for ArkLaMiss. There will be robust lapse rates with this system which is always the first thing I look for...we’re taking 7.0-7.5 C/KM which will lead to strong updrafts.

Everybody's favorite day for severe weather threats down there, right?...
 

Taylor Campbell

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Mods, can you please pin this thread to the top. It looks to be a classic bad one. Thank you.
 

Kory

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And the 12z runs so far doesn’t instill a lot of confidence into this just yet. Things just don’t phase right with the piece of energy diving into the Pacific NW and the cut off piece. Honestly doesn’t look like much of a severe wx threat on the ICON and GFS at all.
 
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And the 12z runs so far doesn’t instill a lot of confidence into this just yet. Things just don’t phase right with the piece of energy diving into the Pacific NW and the cut off piece. Honestly doesn’t look like much of a severe wx threat on the ICON and GFS at all.
Sure like to wait till euro has to say first. And also ukie. Gfs doing gfs things as well icon hasn’t been very good lately . Wait see approach. Appears spc siding with euro basically
 

Kory

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This does tend to be the Euro’s range where it outperforms other models. But the last couple systems and their downtrend are fresh in my mind. Will that be the trend this spring, bucking the winter patterns of overperformers? We shall see.
 

Equus

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Kinematics look potentially rather impressive with this, but phasing and thermos of course will tell the tale. Still, I don't want to turn my back on such a dynamic looking system this time of year. On Wednesdays, especially.
 
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And there’s the step toward the GFS with the Euro. SPC is gonna have to redo their outlook for Tuesday if this is the trend. It’s stepping away from a more robust and widespread threat.
Yeah euro is definitely less robust .. one thing hurting this setup is. Trough digging nearly down toward Mexico . This may be turning more into a heavy rain maker if trends keep this
 

Kory

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Yeah euro is definitely less robust .. one thing hurting this setup is. Trough digging nearly down toward Mexico . This may be turning more into a heavy rain maker if trends keep this
I wouldn't go as far as to say the threat is completely gone, but the latest runs have tempered it a bit. I think the 12z GFS was a bit of an overcorrection, but usually something in between the GFS and Euro is a safe bet and that would likely yield some severe weather. I think how far this initial trough dig as well as the upper level jet streak coming into the West Coast (and how the two phase or don't) will determine the threat. We actually have great thermos with these ridiculous ML lapse rates.
 
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