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

[Richardjacks]

I think the potential in the northern/central areas of Mississippi is very serious. As far as west Alabama, I do think there will be a clear cut in the low level instability....all for the same reason. The low level winds are going to back a bit more to the east...this will enhance low level shear but also limit as to how far east the instability will move...if the entire system moves a little slower, west, maybe central Alabama could be more in play

 

[SmokeEater]

Nadocast says Yazoo City part 4 or 5?

Sent from my SM-S901U using Tapatalk

 

[Austin Dawg]

The real question is is it gonna be just storms for Tupelo, or are we gonna see some minor damage, or are we going to be seeing a modern day version of this:
View attachment 15646

I worked in Tupelo in the 80's and early 90's. Ran up there for dinner and a show from my teenage days. They talked about that tornado like it happened last year. Grandma said Poppa went to help but never said much about what he saw, except the odd stuff. Weeds embedded in trees, stacks of concrete sidewalks... Said it looked like a war zone

After growing up in an F5 town I understand. I can't imagine that they found everyone.


1936 Tupelo Tornado


\

 

[cincywx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1109 PM CST MON NOV 28 2022

VALID 291200Z - 301200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS FAR
EAST-CENTRAL LOUISIANA INTO CENTRAL MISSISSIPPI...

..SUMMARY

SEVERE THUNDERSTORMS CAPABLE OF PRODUCING TORNADOES, VERY LARGE
HAIL, AND A FEW SEVERE WIND GUSTS ARE EXPECTED THIS AFTERNOON INTO
THE OVERNIGHT PERIOD ACROSS PARTS OF THE LOWER TO MID MISSISSIPPI
VALLEY AND PARTS OF THE SOUTHEAST. A FEW STRONG TORNADOES WILL BE
POSSIBLE.

..SYNOPSIS

A SURFACE LOW WILL DEEPEN WHILE TRACKING FROM KANSAS TO THE GREAT
LAKES TODAY, ACCOMPANIED BY AN EASTWARD ADVANCING UPPER TROUGH. A
STRONG MID-LEVEL JET STREAM WILL OVERSPREAD AN INTENSE LOW-LEVEL JET
ACROSS THE OH/TN VALLEYS INTO THE SOUTHEAST. AS SUCH, STRONG
DEEP-LAYER FLOW AND SHEAR WILL OVERLAP WITH A MOISTENING,
DESTABILIZING AIRMASS FROM LATE MORNING TO EARLY EVENING FROM THE
LOWER MS VALLEY EAST-NORTHEASTWARD. SEVERAL STRONG TO INTENSE
THUNDERSTORMS ARE EXPECTED TO ORGANIZE AND PROMOTE A RELATIVELY
ROBUST SEVERE THREAT, PARTICULARLY ACROSS THE SOUTHEAST, WHERE
REGIONALLY HIGHER INSTABILITY SHOULD RESIDE.

..PORTIONS OF THE LOWER MS VALLEY TODAY INTO EARLY TONIGHT

STRONG WARM-AIR ADVECTION SHOULD BE UNDERWAY ACROSS THE LOWER MS
VALLEY AT THE START OF THE PERIOD (12Z), WITH RICH BOUNDARY-LAYER
MOISTURE BEING TRANSPORTED NORTHWARD BY A 40-50 KT SOUTHWESTERLY
LOW-LEVEL JET. THROUGH THE DAY, AT LEAST MODEST SURFACE HEATING
SHOULD SUPPORT SURFACE TEMPERATURES RISING INTO THE LOWER 70S F AMID
UPPER 60S F DEWPOINTS WITHIN THE WARM-AIR ADVECTION REGIME, WHERE AN
INCREASE IN THUNDERSTORMS IS ALSO EXPECTED. 50-70 KTS OF
WEST-SOUTHWESTERLY 500 MB FLOW AND 6.5+ C/KM LAPSE RATES WILL
OVERSPREAD THE LOWER MS VALLEY AND THE WARM-AIR ADVECTION REGIME BY
EARLY AFTERNOON, CONTRIBUTING UP TO 1500 J/KG MLCAPE, WHICH IS
ADEQUATE IN SUPPORTING A SEVERE THREAT.

STORMS SHOULD EVENTUALLY ROOT INTO A GRADUALLY DEEPENING BOUNDARY
LAYER DURING THE AFTERNOON, TAKING ADVANTAGE OF THE STRONG
DEEP-LAYER AND LOW-LEVEL SPEED/DIRECTIONAL SHEAR PROVIDED BY THE
OVERLAPPING SOUTHWESTERLY LOW-LEVEL AND WESTERLY MID-LEVEL JETS.
LARGE, CURVED LOW-LEVEL HODOGRAPHS WITH MID/UPPER-LEVEL ELONGATION
WILL SUPPORT WELL OVER 50 KTS OF EFFECTIVE BULK SHEAR, AND 300-400
M2/S2 EFFECTIVE SRH. SUPERCELL STRUCTURES ARE EXPECTED INITIALLY,
WITH LARGE HAIL, TORNADOES, AND A FEW SEVERE GUSTS ALL LIKELY. A FEW
INSTANCES OF 2+ INCH DIAMETER HAIL AND/OR STRONG TORNADOES ARE
POSSIBLE WITH THE MORE ROBUST SUPERCELLS. SHOULD A MORE DOMINANT
SUPERCELL DEVELOP, REMAIN DISCRETE, AND TRAVERSE AN AXIS OF LOCALLY
STRONGER SURFACE HEATING/BUOYANCY, A LONG-TRACKED AND INTENSE
TORNADO MAY OCCUR. THE LATEST HIGH-RESOLUTION GUIDANCE CONSENSUS
SUGGESTS THIS SCENARIO WOULD BE MOST LIKELY ACROSS CENTRAL MS, WHERE
A CATEGORY 4/MODERATE RISK IS IN PLACE. LATER AT NIGHT, STORMS
SHOULD GROW UPSCALE INTO MORE LINEAR SEGMENTS AS THE SURFACE COLD
FRONT AND GREATER LOW-LEVEL CONVERGENCE APPROACHES. DAMAGING GUSTS
SHOULD THEN BECOME THE MAIN THREAT, THOUGH A FEW TORNADOES REMAIN
POSSIBLE.

..PARTS OF THE OH/TN VALLEY INTO EARLY EVENING

A STRONG SURFACE COLD FRONT SHOULD SWEEP ACROSS THE OH/TN VALLEYS
THROUGH THE LATE AFTERNOON AND EVENING HOURS AS THE DEEPENING
SURFACE LOW TRACKS ACROSS THE GREAT LAKES. STRONG CONVERGENCE ALONG
THE COLD FRONT SHOULD FORCE A LOW-TOPPED BAND OF CONVECTION. AMBIENT
TROPOSPHERIC WIND FIELDS WILL BE STRONG, WITH 55+ KTS OF FLOW LIKELY
JUST 1 KM AGL. DOWNWARD MOMENTUM TRANSPORT WITHIN THIS LINE MAY
FOSTER STRONG, OCCASIONALLY DAMAGING GUSTS, WITH A COUPLE OF SEVERE
GUSTS ALSO POSSIBLE, WARRANTING THE INTRODUCTION OF CATEGORY
1/MARGINAL PROBABILITIES THIS OUTLOOK.

..SQUITIERI/DARROW.. 11/29/2022

well-worded disco

 

[Clancy]

well-worded disco

View attachment 15649

Southeastern shift in the MDT.

 

[JBishopwx]

Updated Nadocast

 

[Austin Dawg]

Updated NadocastView attachment 15650

That is really south and east of the SPC warned area.

 

[Equus]

In many of these events (certainly not all though) we get caught off guard by how far east into AL that the threat continues even with marginal instability to work with when wind profiles are this impressive; if storms remain surface based with backed winds, I wouldn't let down guard into central AL for nasty leftovers spinning up a few surprises. For the warm sector, storm mode and junk convection is always a question so we'll see if we get the balance necessary for well spaced supercells, which would lead to a pretty unpleasant day in south-central Mississippi... then again, sometimes it only takes one

 

[KevinH]

00Z HRRR has UH streaks trailing from NE LA all the way into W GA, though I'm not seeing much in the way of instability on the maps once storms reach the area (granted, it doesn't take much this time of year).
View attachment 15645

Uh oh

 

[CheeselandSkies]

09Z HRRR is another nasty run. Has two dominant supercells going this afternoon across northeast LA into western MS.

 

[Smokedevil]

I worked in Tupelo in the 80's and early 90's. Ran up there for dinner and a show from my teenage days. They talked about that tornado like it happened last year. Grandma said Poppa went to help but never said much about what he saw, except the odd stuff. Weeds embedded in trees, stacks of concrete sidewalks... Said it looked like a war zone

After growing up in an F5 town I understand. I can't imagine that they found everyone.


1936 Tupelo Tornado


\View attachment 15648

My grandfather went to help once they got the word hours later ( he only lived about 18 miles away ) but they had no TV or radio back then.

He said Hundreds and hundreds of injured people were loaded up on train cars and sent to surrounding towns hospitals.

He said there was a lake on front street, and you could have walked across it on the bodies of the deceased and not got your feet wet. The lyric theater was turned into a hospital and makeshift morgue.

Fast forward to 2011.
I helped at Smithville ( I'm in the fd and work EMS ) and I'm sure I felt the same as he did at what I saw.

I'm working today in ems, not very far from Smithville. I hope it busts.

 

[Richardjacks]

One trend I am noticing this morning on the hrr is that the initial area of storms in Mississippi is a bit further north. This is allowing the higher Td air from the south to work its way further east...before the arrival of the cold front. If this trend continues, we will see threats ramp up further east as the intials storms around the warm front remain back to the north and west,

 

[JPWX]

12z HRRR max updraft helicity swath.

 

[xJownage]

One thing that has made me more concerned for N MS is that the southern convection doesn't appear nearly as widespread/robust early in the time period. this will mean that we WON'T see blocking of warm air advection in the northern portion of the target. may allow the WF to get further north as well. This will also result in our thermals overperforming slightly in all likelihood, especially further east.

 

[CheeselandSkies]

HRRR just continues to be nasty run after run with multiple intense, long-tracked supercells across MS.

Some analogs for possible impact levels in that state that come to mind are:

4/24/10 (monster long tracked Yahoo City EF4)
4/28/14 (Louisville EF4, Tupelo EF3)
12/23/15 (Clarksdale EF3-Holly Springs EF4 family)
Easter 2020 (Bassfield EF4 family)

 

[Taylor Campbell]

Today’s moderate for this area has me more concerned than other moderate risk we’ve seen in the last several years for this area. Looks less messy and more likely to verify on the upper end.

 

[CheeselandSkies]

Today’s moderate for this area has me more concerned than other moderate risk we’ve seen in the last several years for this area. Looks less messy and more likely to verify on the upper end.

Yep. Not all 15% hatched MDTs are created equal.

 

[Gail]

Meanwhile in the the moderate area, the skies are blue and it’s in the upper 40s this morning. It doesn’t have that usual severe weather feel in the air and is deceptively gorgeous out this morning. I hope this evening doesn’t catch a lot of people off guard. I’ve noticed the schools have cancelled games so that’s great! Night time events always worry me.

 

[CheeselandSkies]

SPC hitting it hard on the 13Z (and it's not even a Broyles outlook!):

..Lower Mississippi Valley to Lower Ohio Valley and central Gulf
Coast...

Multiple rounds of severe thunderstorms -- some capable of long-
tracked tornadoes with EF3+ damage potential -- will be possible
this afternoon into tonight over parts of the lower Mississippi
Valley region and Mid-South. Large, locally damaging hail and
strong-severe thunderstorm gusts also are expected over the region.

Usually they just stick to "strong tornado" wording, technically meaning anything EF2+. Pretty rare the times they explicitly go above that.

 

[xJownage]

Being that our dynamics are at least partially driven by a subtropical jet, this setup is a lot different than normal dixie setups. The extremely subtle forcing well ahead of the influencing front almost guarantees a discrete mode that can be maintained for hours with multiple rounds possible given enough warm air advection. The lack of convection in the southern half of the target area early on will also make warm air advection easier, making multiple rounds more likely.

Look for SFC backing. Also, keep an eye on these elevated cells in AR right now. Should they intensify, they could leave some weak outflow boundaries, which could serve as spots for both initiation and enhanced SRH to assist in tornadogenesis with ongoing cells.