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Severe Weather Threat - November 29th-30th, 2022

CheeselandSkies

CheeselandSkies

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Some pretty ominous wording again from Memphis:

Area Forecast Discussion
National Weather Service Memphis TN
553 PM CST Mon Nov 28 2022

...New AVIATION...

.DISCUSSION...
(This evening through next Sunday)
Issued at 336 PM CST Mon Nov 28 2022

A potential high-end severe weather event remains on track to
impact the Midsouth on Tuesday and Tuesday night. Tornadoes, a
few strong and long-lived, will be possible.

Low level moisture and instability will surge north through the
lower MS River valley Tuesday morning, in advance of a deepening
upper level longwave trof over the Great Plains. Initial round of
late morning/early afternoon storms will likely root in an elevated
layer, associated with a 925mb warm front surging north from the
Arklamiss. These storms will likely present a marginal severe
threat in the early afternoon, with midlevel lapse rates of 6.5
C/km accompanying MUCAPE below 300 J/KG.

The potential for storms to become rooted in a near-surface layer
will increase mid to late afternoon, aided by modest surface
heating and dewpoints rapidly warming into the mid/upper 60s.
During this period, convection-allowing model (CAM) consensus
depicts 850mb wind increasing from 40 to 60 KTs, elongating
hodographs and increasing 0-3km helicity to values in excess of
500 m2/s2.

Uncertainty remains regarding the extent and timing of low level
inversion erosion in the absence of strong surface heating. This
will largely determine the northward extent of the tornado threat
in the late afternoon, prior to steep midlevel height falls.

While some uncertainty remains regarding the onset timing of
surface-based convection and associated tornado threat, the
parameter space will become quite concerning by early Tuesday
evening, aided by CAPE in excess of 1000 J/kg and steep height
falls and strongly bowed hodographs. Low LCLs (cloud bases) and
storm movement in excess of 60 mph will make for particularly
dangerous convective environment, where tornadic storms appear to
arrive suddenly, preceded by little if any visual or audible
notice. Definitely a time to keep a weather radio with battery
backup and a fully-charged cell phone nearby.

Beyond Tuesday`s severe event, generally quiet weather is
forecast from through the upcoming weekend, under fast zonal flow
aloft. A northern branch upper low will pass through the Great
Lakes on on Saturday, modestly depressing midlevel heights over
the Midsouth and aiding the passage of a Pacific cold front. A few
showers will accompany the frontal passage, with only limited
chances for thunder.

PWB

&&
Click to expand...
 
Justin Hindman

Justin Hindman

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My idea of the risk. Yes it’s different from the spc some, but I the moderate risk I have highlight is where the most tornado reports will come out of. Memphis is under the gun but I think the best risk is south of Memphis. I have more of southern Mississippi under the moderate as well due to non impediment in storm weakening as we learned on Easter Sunday. Only question for southern Mississippi is will the dynamics be a little further north but the dewpoints and cape are highest here. I extended the enhanced well into Alabama for the wind threat. Posting it now to see how everything lines up afterward. Stay safe everyone.
 

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JPWX

JPWX

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Justin Hindman said:
My idea of the risk. Yes it’s different from the spc some, but I the moderate risk I have highlight is where the most tornado reports will come out of. Memphis is under the gun but I think the best risk is south of Memphis. I have more of southern Mississippi under the moderate as well due to non impediment in storm weakening as we learned on Easter Sunday. Only question for southern Mississippi is will the dynamics be a little further north but the dewpoints and cape are highest here. I extended the enhanced well into Alabama for the wind threat. Posting it now to see how everything lines up afterward. Stay safe everyone.
Click to expand...
That's honestly a good outline. Another concern I have outside of the tornado threat is the flash flooding risk. I know that's not been talked about much but the past runs of the HRRR have shown pretty good rainfall amounts (as well as training potential) from Tupelo down to Columbus.
 
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