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Severe WX Severe Threat 17-18 March 2021

Equus

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The middle part of the high in Mississippi definitely busted in regard to tornadoes, most of the tornado reports were on the south and east edges of the high. I assume the high was to emphasize that the combined number of tornadoes in the afternoon round and nighttime round would be concentrated enough to warrant the risk level, but the nighttime event never really materializing hampered verification there. High was a good call, we had numerous damaging tornadoes, but it certainly underperformed the 45% and with much of the risk area staying stable or not having warnings at all, it's not going to help future response to severe weather regardless of verification. Can't really win; verify and massive death and destruction, underperform and complacency kills more the next time.
 
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The middle part of the high in Mississippi definitely busted in regard to tornadoes, most of the tornado reports were on the south and east edges of the high. I assume the high was to emphasize that the combined number of tornadoes in the afternoon round and nighttime round would be concentrated enough to warrant the risk level, but the nighttime event never really materializing hampered verification there. High was a good call, we had numerous damaging tornadoes, but it certainly underperformed the 45% and with much of the risk area staying stable or not having warnings at all, it's not going to help future response to severe weather regardless of verification. Can't really win; verify and massive death and destruction, underperform and complacency kills more the next time.
Very true. I hope the public doesn't become complacent. Last Easter's outbreak and this one won't be perceived as living up to expectations and forecasts due to lack of dramatic, widespread effects. We should be relieved and not cynical.
 

keithGA

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Anyone care to share any insight they have as to why the models handled the wedge east of the apps so poorly? Models showed it eroding, but it never really did. Thankful for it as it saved me from any severe weather in my area.
 

warneagle

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I guess the big question is why supercells never formed in central Mississippi. The soundings from LIX and JAN certainly favored tornadic supercells, but they just never formed.
 

Equus

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Mississippi not firing definitely hurt verification. If we'd had the concentration of supercells there that we had in AL, there wouldn't be nearly as much talk about underperformance.

The QLCS wiping out the environment for the potential last round of cells also affected things, but perhaps it isn't surprising to see a QLCS wipe the environment since that's just what Dixie does...
 
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Very true. I hope the public doesn't become complacent. Last Easter's outbreak and this one won't be perceived as living up to expectations and forecasts due to lack of dramatic, widespread effects. We should be relieved and not cynical.
People seriously think the Easter Outbreak last year underperformed? It dropped the third-most tornadoes ever in a 24-hour period, only getting beaten out by the legendary 1974 and 2011 Super Outbreaks. All I've seen is people being surprised with how prolific and potent the system was, especially the overnight QLCS.
 

Equus

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The 4/27 syndrome is still alive and well honestly, anything that doesn't produce widely spaced long lived tornadic supercells dropping strong tornadoes in populated areas (extraordinarily rare in Dixie!) is seen as underperforming by a lot of the public. 3/1/07 was seen as a bust by much of northern AL as was 4/28/14 despite producing widespread strong tornadoes and deadly violents in both cases. Some people's perceptions probably won't change.
 

pohnpei

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People seriously think the Easter Outbreak last year underperformed? It dropped the third-most tornadoes ever in a 24-hour period, only getting beaten out by the legendary 1974 and 2011 Super Outbreaks. All I've seen is people being surprised with how prolific and potent the system was, especially the overnight QLCS.
I think Easter was one of the most overperformed MDT in the history. The Bassfield Supercell and overnight QLCS activity in GA/SC was historical. The only MDT case I can think of was even more overperformed was 90/3/13.
 

warneagle

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The 4/27 syndrome is still alive and well honestly, anything that doesn't produce widely spaced long lived tornadic supercells dropping strong tornadoes in populated areas (extraordinarily rare in Dixie!) is seen as underperforming by a lot of the public. 3/1/07 was seen as a bust by much of northern AL as was 4/28/14 despite producing widespread strong tornadoes and deadly violents in both cases. Some people's perceptions probably won't change.
That's true to an extent, but zero tornado reports in the Mississippi portion of the high risk is a forecast bust by any standards. Not saying the event as a whole was a bust since we'll likely have 30+ tornadoes and several significant ones, but that specific part of the forecast area objectively didn't verify.
 

Equus

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Oh yeah the Mississippi part completely objectively busted horribly, doesn't mean it was a bad forecast but there is definitely a glaring lack of red dots there.
 

WhirlingWx

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Mesoscale Discussion 0222
NWS Storm Prediction Center Norman OK
1005 AM CDT Thu Mar 18 2021

Areas affected...Central into eastern Georgia and southern South
Carolina...and far northern Florida

Concerning...Tornado Watch 39...

Valid 181505Z - 181700Z

The severe weather threat for Tornado Watch 39 continues.

SUMMARY...Severe storms remain possible within WW 39, with a tornado
or damaging wind threat shifting east into the afternoon. An
additional watch is likely downstream of WW 39.

DISCUSSION...A line of storms currently extends from central and
southern GA into the eastern FL Panhandle. This activity has been a
bit disorganized, with only brief areas of rotation or shear zones
noted on radar. One notable cluster of storms was located over
Laurens County GA as of 15Z.

While these storms currently exist near the instability axis with
MLCAPE at or above 500 J/kg, objective analysis shows only weak
instability downstream into eastern GA and SC. With time, this area
will destabilize as well as dewpoints rise and if pockets of heating
develop. An axis of 200-300 m2/s2 effective SRH is forecast to
remain ahead of the developing dryline, and will support a supercell
and tornado threat later today.

..Jewell.. 03/18/2021
 

TH2002

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Video of the HUGE tornado that hit Selma/Burnsville yesterday:



Have yet to see any damage shots from that area, though the roar of the tornado is very audible.
 

Argus

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We are about to punch through the dry line near Winder right now. Heading to Atlanta to take co-worker to doctor.
 

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catatonia

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6/17/10 in Minnesota.
Well, going way back, I don't see May 31 1985 in the SPC high-risk archive -- at least according to Wiki.


Although the article says the data might be incomplete for high-risk days that long ago. Would be interesting to know for a fact if it indeed was "just" a moderate day. If there are any answers to that question, it would be from this great forum, which I finally joined. So many educational posters here. Thanks to them all.
 

WhirlingWx

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New tornado watch out, this isn't over the moderate risk. 50/30 tornado probabilities

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 40
NWS Storm Prediction Center Norman OK
1140 AM EDT Thu Mar 18 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
North Florida
Eastern Georgia
Southern South Carolina
Coastal Waters

* Effective this Thursday morning and evening from 1140 AM until
600 PM EDT.

* Primary threats include...
A few tornadoes and a couple intense tornadoes possible
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A broken line of thunderstorms should spread
east-northeast from south-central Georgia and the eastern Florida
Panhandle. Intensification is expected with the development of a few
embedded supercells this afternoon. Tornado and damaging wind are
the primary hazards.
 
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