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Discussion of April 27, 2011 Outbreak (1 Viewer)


Equus

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Messages
859
Location
Saragossa, AL
I'd have to agree, I would not at all be surprised to see another event or two of that magnitude in my lifetime. I would also not be surprised if somewhere in the state there is someone alive that remembers all three of the 'once in a lifetime' events in 32, 74, and 11. Statistically speaking, we are going to have a comparable event again someday, and the chances are just as good if not better of it happening in my lifetime as not.

I wish we could study pre-European settlement tornadoes here like we can with sediment cores for hurricanes. It'd be very hard if not impossible to do, but it would be extremely fascinating. If only we had tree species in the area that as a whole tended to live as long as some of the western conifers to help us out.
 
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160
Location
Daleville, AL
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Funny thing is when they say now to have multiple ways of getting warnings like in the middle of the night. My idea is the built in EAS tone alert that comes from Verizon and then TWC and im subscribed to INWS so get text also (which TWC always beats-imagine that). There I have 3 ways! Didn't think about cell phone towers going down like in MichelleH's case but 4/27/11 is probably where this advice came from. I feel this is exceptionally rare but obviously can happen. I had a weather radio but my location didn't pick up the station in Texasville AL that actually covered my county although it picked up the station in Bethlehem FL that doesn't sound alerts for me perfectly and crystal clear. What would people in a situation such as this use? I can remember a TV station in FL years ago advising people to keep their TV on during a hurricane so if a tornado warning was issued the EAS alert would hopefully wake them up since it was louder than normal programming.
 

GTWXAlum

Member
Messages
57
Location
Atlanta, GA
One thing I thought was interesting is how well this event was anticipated, discussed, and forecasted by the various affected NWS offices days (even a week +) in advance. For example, here is the first mention of the event from NWS Birmingham in their overnight AFD from Tuesday, April 19 (8 days in advance):

"UNFORTUNATELY...THIS VERY ACTIVE WEATHER PATTERN LOOKS LIKE IT
WILL CONTINUE TO SPIN UP SURFACE LOWS LEE OF THE ROCKIES THROUGH
NEXT WEEK...AND LONG RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN
THE DEVELOPMENT OF A DEEPLY AMPLIFIED TROUGH DIGGING INTO THE
SOUTHERN PLAINS BY MONDAY...AND THOUGH THE RIDGE MAY HOLD IN PLACE
FOR THE FIRST SURFACE LOW...BOTH THE GFS AND THE EURO SHOW A SECOND
SHORTWAVE PROPAGATING AROUND THE BASE OF THE LONGWAVE TROUGH AND
WASHING RIDGE FURTHER DOWNSTREAM. THIS MAY OPEN THE DOOR FOR MORE
SEVERE WEATHER BY THE MIDDLE OF NEXT WEEK. WILL INTRODUCE THIS INTO
THE HWO IF IT PERSISTS TOMORROW."
 

WesL

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Huntsville, AL
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Fast forwarding to the future. It is my pleasure to announce that TalkWeather is taking over the online memorial for Alabama Remembers 4/27. This year we will restart the tradition of posting each name via social media and we will eventually have Alabama427.com up and running with more information including memories and photos submitted by families.

Here are a few handy links to check out on the 8th anniversary of the super outbreak.

Links to Alabama Remembers social media accounts:

Twitter –
https://twitter.com/AL_427_Memorial

Facebook-
https://www.facebook.com/Alabama427/

Announcement for Alabama Remembers and TalkWeather partnership:
https://blog.talkweather.com/special-projects/tw-alabama427-memorial/

TalkWeather Reconstructed Archive of the 4/27/2011 event (thanks to @Equus and @KoD):
 

Gail

Member
Messages
61
Location
Caledonia, MS
I wish I had saved it, but obviously, Jackson’s forecast discussion was very concerning. I know not many outside the weather world read those often (or at all) though. I do know that day changed a lot of people around here in many ways - schools and businesses too. It’s still so heartbreaking to think about.

0986BD03-FCA5-4BC2-BFA4-E1DEB13970A1.jpeg
 

WesL

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I wish I had saved it, but obviously, Jackson’s forecast discussion was very concerning. I know not many outside the weather world read those often (or at all) though. I do know that day changed a lot of people around here in many ways - schools and businesses too. It’s still so heartbreaking to think about.

View attachment 1597
Is this the one you are looking for?

Here is April 26, 2011 -
467
FXUS64 KJAN 270130 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
830 PM CDT TUE APR 26 2011

...SIGNIFICANT SEVERE WEATHER EVENT CURRENTLY UNFOLDING...TIMEFRAME
IS FOR TONIGHT INTO WEDNESDAY...

.UPDATE...LATEST SATELLITE IMAGERY SHOWED STRONG UPPER TROUGH OVER THE
SOUTHERN PLAINS...WHICH WAS PROVIDING AN OUTBREAK OF SEVERE WEATHER FROM
THE AROUND THE ARKLATEX TO THE MIDSOUTH REGION. CURRENT FORECAST APPEARS
TO THE ON TRACK FOR SEVERE STORMS TO AFFECT THE REGION AS PREVIOUSLY
DISCUSSED. OVERNIGHT TEMPS LOOK TO BE ON TRACK. LATEST RUC AND SHORT
RANGE ENSEMBLES HAS IT AFFECTING THE REGION LATER TONIGHT./17/

./PREVIOUS DISCUSSION...355 PM CDT
.DISCUSSION...MAJOR SEVERE WEATHER OUTBREAK READY TO UNFOLD FROM THE
ARKLATEX THROUGH OUR FORECAST AREA INTO AL AND TN VALLEY TONIGHT
INTO WED. THIS EVENT WILL BE THE FOCUS OF THIS FORECAST FOR THE NEXT
24HRS THEN A SHIFT TO COOLER AND DRIER CONDITIONS INTO THE WEEKEND.

ACROSS THE AREA TODAY...THE ATMS IS QUICKLY RESPONDING AND
RECOVERING FROM THE MORNING STORM COMPLEX. BASED OFF VAPOR
IMAGERY...SEVERAL DISTURBANCES ARE NOTED IN THE MEAN UPPER TROUGH.
IT IS THESE FEATURES...ALONG WITH THE MAIN DIGGING TROUGH...THAT IS
CAUSING SFC PRESSURES TO LOWER ACROSS TX WHICH IS IN TURN ALLOWING
PRESSURES TO FALL OVER OUR REGION. FORECAST MODELS SEEM TO BEING
WELL WITH THE ABV FEATURES I MENTIONED AND SHOW THE RAPID RESPONSE
TO THE WIND FIELDS AND RECOVERY OF THE ATMS. TAKING THE VARIOUS
MODEL GUID ALONG WITH HI-RES OUTPUT...MULTIPLE ROUNDS OF STORMS
APPEAR POSSIBLE WITH THE VARIOUS EMBEDDED WAVES FROM LATE THIS
AFTERNOON...EVENING/OVERNIGHT AND THEN ON WED.

AS THE ENVIRONMENT RESPONDS TO THE INTENSE UPPER TROUGH AND EMBEDDED
WAVES...SVR WX PARAMETERS WILL INCREASE AND REACH EXTREME LEVELS.
INSTABILITY WILL NOT BE EXTREME...BUT WILL BE STRONG AND AT LEVELS
RATHER HIGH FOR THE OVERNIGHT PERIOD. AS SFC WINDS REMAIN STRONG
OVERNIGHT DUE TO LOWERING PRESSURES...THE BOUNDARY LAYER WILL REMAIN
WELL MIXED. LOOK FOR MLCAPE TO HOLD IN THE 1500-2300 J/KG RANGE WITH
7 TO 8 C/KM LAPSE RATES IN PLACE. A LOW LEVEL CAP WILL DEVELOP AS
WELL AND HELP TO LIMIT THE STORM COVERAGE...ESPECIALLY FOR THE
SOUTHERN HALF. AS FOR SHEAR PARAMETERS...EFFECTIVE SRH VALUES WILL
RAPIDLY INCREASE EARLY THIS EVENING AND INTO WED. THESE SRH VALUES
WILL APPROACH EXTREME LEVELS AND RANGE FROM 400-800 M2/S2. THIS
COMBINATION SHEAR/INSTABILITY IS VERY RARE AND CONDUCIVE FOR
SIGNIFICANT SVR STORMS. ADDITIONALLY...THE POSITION OF THE MID LEVEL
HGHTS...SFC LOW AND VALUE OF THE SFC PRESSURES HISTORICALLY SUPPORT
A SIGNIFICANT EVENT WHEN OVERLAID OVER SUFFICIENT INSTABILITY. THE
AREA WILL ALSO SEE ANOTHER DRY LINE FEATURE PUSH INTO THE REGION AND
TYPICALLY THAT LEADS TO A SUBSTANTIAL EVENT.

THE AREAS UNDER THE GREATEST RISK HAVE NOT CHANGED. LOCATIONS NORTH
OF I-20 CONTINUE TO HAVE THE GREATEST RISK WITH AREAS ALONG AND S OF
I-20 HAVING A MORE ISOLATED RISK. THE SOUTHERN HALF WILL HAVE TO
COMPETE WITH LOW/MID LEVEL CAPPING AND ALL INDICATIONS ARE THAT IT
WILL BE TOUGH TO BREAK THE CAP EVEN IN THE FACE SUCH INTENSE
FORCING. HOWEVER...IF ANYTHING CAN DEVELOP...CONDITIONS WILL BE VERY
FAVORABLE FOR HIGH END SVR STORMS. THE NORTHERN HALF WILL LIKELY
HAVE SOME CAP...BUT IT WON'T BE AS STRONG AND THE DEPTH OF MOISTURE
AND ASCENT WILL ALLOW FOR MULTIPLE ROUNDS OF STORMS. THE REPETITIVE
EXPECTATION OF STORMS WILL LIKELY LEAD TO LOCALLY HEAVY RAINS ACROSS
THE NORTH WITH 3-6 IN TOTALS POSSIBLE. SOME HIGHER AMOUNTS COULD
ALSO OCCUR. DUE TO THIS...HAVE EXPANDED THE AREA OF THE FLASH FLOOD
WATCH.

THE SEVERITY OF THIS EVENT WILL ULTIMATELY COME DOWN TO STORM MODE
(SUPERCELL VS SQUALL LINE). AT THIS TIME...IT SEEMS AS THE CWA WILL
SEE A MIXTURE OF BOTH THROUGH THIS EVENT. WITH ANY SUPERCELL
STORM...THERE WILL EXIST THE POSSIBILITY OF LONG TRACK STRONG
TORNADOES....VERY LARGE HAIL AND DMG WINDS TO 80 MPH. AS FOR ANY
LINE SEGMENT...DMG WINDS TO 80 MPH WILL BE THE PRIMARY RISK WITH
HAIL AND TORNADOES ALSO A SUBSTANTIAL RISK. EITHER WAY AND WHICH
EVER MODE OCCURS...THE RISK FOR SIGNIFICANT SVR WX IS POSSIBLE.

AS FOR TIMING...THERE IS NO SPECIFIC TIME...JUST A LARGE WINDOW OF
FAVORABLE CONDITIONS ACROSS THE N HALF FROM NOW THROUGH WED
AFTERNOON. I WOULD SAY THAT THE SE PORTION OF THE CWA WILL WAIT
UNTIL AT LEAST MID/LATE MORNING AND DURING WED AFTERNOON. I DO FEEL
CONFIDENT THAT THINGS WILL PUSH EAST AND EXIT THE AREA BY 7 PM WED.

IN ADDITION TO ALL THE SVR WX...SFC WINDS WILL INCREASE OVERNIGHT
AND BECOME QUITE GUSTY. THE STRONGEST WINDS LOOK TO OCCUR ON WED AS
THE AREA WARMS AND MIXES DOWN THE INTENSE WINDS JUST OFF THE SFC.
ADDITIONALLY...WHEN THE DRY LINE MOVES ACROSS THE W/NW
AREAS...DEEPER MIXING WILL OCCUR AND HELP TO BRING DOWN WINDS OF
40-50 MPH. FOR NOW...HAVE ISSUED A WIND ADV FOR ALL OF THE AREA.
PORTIONS OF THE W/NW MAY NEED A HIGH WIND WARNING. THIS WILL BE
LOOKED AT CLOSER IN LATER FORECASTS AND UPDATED AS NEEDED.

BEYOND 8 PM TOMORROW...CONDITIONS WILL BE QUIET WITH COOLER AND MORE
SEASONAL CONDITIONS EXPECTED. NEXT REAL CHANCE AT PRECIP LOOKS TO
WAIT UNTIL SUN OR MON. /CME/

&&

.AVIATION...DANGEROUS FLYING WEATHER IS EXPECTED OVER THE NEXT 24-30
HOURS AS SEVERAL ROUNDS OF SEVERE TSRA(LARGE HAIL/SEVERE
TURBULENCE/WIND SHEAR) IMPACT THE ARKLAMISS. FIRST ROUND OF STORMS
IS EXPECTED TO BEGIN OVER THE DELTA AROUND 22-24Z THIS
EVENING...WITH CONTINUED TSRA DEVELOPMENT ACROSS THE DELTA/NORTHERN
MS LATER TONIGHT. SCATTERED TO NUMEROUS SHWRS/TSTMS WILL BEGIN
IMPACTING THE REGION TOMORROW MORNING AS A FRONTAL BOUNDARY
APPROACHES THE REGION FROM THE WEST. VFR CONDS WILL PERSIST THIS
AFTN INTO THIS EVENING WITH A TREND TOWARD MVFR/IFR CIG 07-13Z FOR
AREAS ALONG AND EAST OF I-55. MVFR/OCSNL IFR CIG XPCTD INVOF
SHWR/TSTM ACTIVITY. IN ADDITION... SOUTHERLY SFC WINDS WILL REMAIN
GUSTY THRU THE PERIOD...WITH GUSTS TO 40KTS PSBL AFTER 03Z THIS
EVENING...ESPECIALLY OVER THE DELTA. /BK/



April 27, 2011

317
FXUS64 KJAN 271551
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
1051 AM CDT WED APR 27 2011

...SIGNIFICANT SEVERE STORMS AND TORNADO OUTBREAK EXPECTED THIS
AFTERNOON...

.UPDATE...NOT MUCH HAS CHANGED WITH OUR THINKING AND THE OVERALL
EVOLUTION FOR TODAY. HOWEVER...THE DETAILS ARE BECOMING A BIT MORE
CLEAR BASED OFF LATEST HI-RES MODELS AND TRENDS WITH RADAR AND SAT
IMAGERY.

A VOLATILE SITUATION IS DEVELOPING WHICH LOOKS TO SUPPORT SEVERAL
SUPERCELL STORMS MOVING ACROSS THE CWA FROM LATE MORNING AND DURING
THE AFTERNOON. THE COMBINATION OF INSTABILITY AND LOW LEVEL SHEAR IS
OFF THE CHART AND AT LEVELS RARELY SEEN. EFFECTIVE SRH VALUES ARE
CURRENTLY 600-900 M2/S2 AND FORECAST TO REMAIN VERY HIGH AND WILL
LIKELY HOLD IN THE 300-600 M2/S2 RANGE IF NOT HIGHER. INSTABILITY
WILL BE QUITE HIGH AS WELL AND EXCEED 2500-3000 J/KG IF DEWPTS HOLD
AROUND 70. FORCING WILL BE INTENSE AND THERE WILL BE SOME CAPPING
MOVING IN FROM THE SW. THIS SHOULD KEEP CELLS DISCRETE AND
SUPERCELLULAR TODAY. DEEP LAYER SHEAR IS PUSHING 80 KTS AND COULD GET
HIGHER AS A 100KT MID LEVEL JET CORE PUNCHES INTO THE REGION IN A FEW
HRS.

EVOLVING SUPERCELLS IS THIS EXTREME ENVIRONMENT IS BAD NEWS. THERE
WILL LIKELY BE SEVERAL STRONG TORNADOES WITH A VIOLENT TORNADO
POSSIBLE. CURRENT SIGTOR PARAMETERS (10-12) AND 0-1KM EHI VALUES (9-12)
ARE EXTREME ABOUT AS CLASSIC AND SIGNIFICANT OF A SETUP AS THEY COME.
STORMS WILL MOVE QUICKLY NE IN THE FAST DEEP LAYER FLOW AND STORMS
SHOULD AVG 50-60 MPH. THIS SETUP WILL ALSO SUPPORT LONG LIVED
SUPERCELLS AND LONG TRACKED TORNADOES. I CAN'T STRESS ENOUGH HOW
DANGEROUS A SITUATION THIS APPEARS. OUR SAVING GRACE WOULD BE IF
STORM MODE SOME HOW BECOMES MORE LINEAR...BUT ALL HI-RES GUID
SUPPORTS DISCRETE CELLS. IN ADDITION TO TORNADOES...VERY LARGE HAIL
WILL BE POSSIBLE ALONG WITH DMG WINDS OF 60-80 MPH.

TIMING WILL BE FROM NOON TO 7 PM WITH A STEADY EASTWARD PROGRESSION
TO THE ACTIVITY DURING THE AFTERNOON. BASED OFF STORM
INITIATION...MESOCYCLONE MATURITY...AND STORM PROPAGATION...THE AREA
AT GREATEST RISK FOR STRONG/VIOLENT TORNADOES LOOKS TO EXIST WITHIN A
ZONE FROM GREENWOOD TO VICKSBURG TO LAUREL AND POINTS E/N OF THAT
LINE. AREAS OUTSIDE THAT WILL HAVE THE POTENTIAL FOR HIGH END SVR
STORMS AS WELL...BUT THAT AREA HAS THE GREATEST OVERLAP OF ALL
PARAMETERS.

OUTSIDE THE SVR STORMS...FLASH FLOODING IS STILL A POSSIBILITY ACROSS
THE NORTH. RAINFALL FROM LAST NIGHTS COMPLEX HAS SET THE STAGE AND
ANY ADDITIONAL ACTIVITY TODAY COULD CAUSE FLOODING ISSUES IF TRAINING
OCCURS. AS THE AREA WARMS THIS MORNING...VERY STRONG WINDS WILL MIX
DOWN AND CAUSE WINDY CONDITIONS...GUSTS TO 30-40 MPH WILL BE
POSSIBLE. AS THE DRY LINE ENTERS THE W/NW...WINDS COULD POTENTIALLY
GET STRONGER AND GUST TO 50 MPH. /CME/

&&

.AVIATION...DANGEROUS FLYING WEATHER IS EXPECTED OVER THE NEXT 12-18
HOURS AS ANOTHER ROUND OF SEVERE TSRA(LARGE HAIL/SEVERE TURBULENCE/
WIND SHEAR)IMPACT THE ARKLAMISS. SCATTERED TO NUMEROUS TSRA WILL
BEGIN IMPACTING THE REGION 17-21Z AS A FRONTAL BOUNDARY CROSSES LA
AND MOVES INTO WRN MS BY 00Z FROM THE WEST. PREVAILING VFR
CONDITIONS WILL PERSIST OUTSIDE OF CONVECTION WITH GUSTY S WINDS OF
20-35KTS THIS AFTN INTO THIS EVENING UNTIL THE FROPA WHEN WNW FLOW
TAKES OVER AND WINDS DIMINISH TO 10-25KTS. DRYING AIR MASS LATER
TONIGHT WILL LEAD TO A COUPLE OF VFR CLEAR DAYS TO FOLLOW./40/

 

akt1985

Member
Messages
410
Location
Madison, Alabama
Something about 4/27/11 that I do not understand. Many of the news outlets reported that 4/27/11 was the deadliest day for tornadoes since 3/18/1925, the tri-state tornado. Wouldn’t 4/27/11 actually been the deadliest tornado day since 4/3/74?
 

Tennie

Member
Messages
141
Location
Tennessee
Something about 4/27/11 that I do not understand. Many of the news outlets reported that 4/27/11 was the deadliest day for tornadoes since 3/18/1925, the tri-state tornado. Wouldn’t 4/27/11 actually been the deadliest tornado day since 4/3/74?
4/27/11 killed more people than 4/3/74 (and all that despite the major advances in technology and science that had been made between the two days!).

On another note, I found this commemoration image of the event, originally made for the fifth anniversary:



Artist's description:
Five years ago, the biggest tornado outbreak in history struck the United States. On a four days - storm system that brought over 300 tornadoes, this one was the most extreme, with 199 tornadoes in less than 24 hours (the previous record was 148, on April 3rd, 1974) over the eastern half of the U.S., with Alabama, Mississippi, Georgia and Tennessee suffering the worst impacts (mainly Alabama, with over 250 deaths of the total 363).
 

warneagle

Member
Messages
1,174
Location
Silver Spring, MD
Special Affiliations
SKYWARN® Volunteer
Some of the major advances in technology from the 1974 Super Outbreak to the 2011 Super Outbreak were kind of rendered moot by the power and communications outages. It doesn’t matter how good your forecasts and warnings are if the people who need the information can’t get it.
 

amanda90

Member
Messages
22
Location
Memphis TN
Some of the major advances in technology from the 1974 Super Outbreak to the 2011 Super Outbreak were kind of rendered moot by the power and communications outages. It doesn’t matter how good your forecasts and warnings are if the people who need the information can’t get it.
Not to mention warning fatigue. Even though Tuscaloosa had just had a tornado the previous week, I had quite a few friends not even realize we had a severe threat that day. And despite the long lead time on the tornado, there were a ton of people in my dorms who were slow to seek cover because they just didn't believe it was real. I'll never forget one of my best friends telling me "Spann is a fearmonger" when I told her what might happen that day.

Even now, with my family knowing what I saw firsthand and better warning parameters across the board, they don't pay attention to the weather. And they were in Memphis for 4/27/11, so it's not like they got out *totally* unscathed.
 

Argus

Member
Messages
96
Location
Athens, Georgia
The MCS that came through Alabama that morning died a quick death before bothering Atlanta and us. I remember it being a nice day here. We monitored the weather coverage, mainly Spann and TWC. I watched everything live, and was very worried for everyone "back home". The next week, we headed to Birmingham for a funeral (non storm related), and couldn't find a hotel room, except in Roebuck, due to the linemen from out of state using them up.
 
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Messages
347
Location
Niagara Falls, Ontario
I remember seeing a photo somewhere of the Smithville tornado as it was moving through town, and the clay it was scouring up from the ground turned the funnel blood red. I'm not very superstitious, but that photo would have been taken right as a lot of people were losing their lives. Coincidence? Yeah, but it's chilling anyway, and reminds me of the "Dead Man Walking" photo of the Jarrell, TX tornado.

I can't seem to find the original photo anymore, but there is a low-contrast version of it here (the red tint is still very slightly visible):
1600
 
Messages
328
Location
Madison, WI
That's one of the clearest images I've ever seen of the Smithville tornado. It resembles the 1999 Bridge Creek-Moore F5 in its wedge stage with the dramatic, RFD-chisled updraft tower looming above it, only it was moving 30-40 MPH faster than that one was.
 

warneagle

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Location
Silver Spring, MD
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That's one of the clearest images I've ever seen of the Smithville tornado. It resembles the 1999 Bridge Creek-Moore F5 in its wedge stage with the dramatic, RFD-chisled updraft tower looming above it, only it was moving 30-40 MPH faster than that one was.
There’s some great footage on YouTube of the tornado moving through Smithville taken from a nearby waterway that’s pretty jaw-dropping. It illustrates both how massive the tornado was and how fast it was moving.

One thing that really interested me as I was looking back at some of the footage over the weekend was the number of tornadoes which had horizontal vortices associated with them. This seems like a pretty rare thing, but I’m admittedly not familiar with the physical properties behind them. Was it just a product of how intense the wind shear was that day?

I also noticed that in a few of the storms (e.g. Philadelphia, MS) the funnel is clearly tilted in the direction of the storm’s forward motion. Is that just a result of how fast the parent storm was moving and the lower part of the funnel being slowed down because it was experiencing more friction? This was also something I haven’t seen a whole lot in other events, but there weren’t too many other cases of tornadoes that intense moving that quickly.
 
Messages
328
Location
Madison, WI
There’s some great footage on YouTube of the tornado moving through Smithville taken from a nearby waterway that’s pretty jaw-dropping. It illustrates both how massive the tornado was and how fast it was moving.

One thing that really interested me as I was looking back at some of the footage over the weekend was the number of tornadoes which had horizontal vortices associated with them. This seems like a pretty rare thing, but I’m admittedly not familiar with the physical properties behind them. Was it just a product of how intense the wind shear was that day?

I also noticed that in a few of the storms (e.g. Philadelphia, MS) the funnel is clearly tilted in the direction of the storm’s forward motion. Is that just a result of how fast the parent storm was moving and the lower part of the funnel being slowed down because it was experiencing more friction? This was also something I haven’t seen a whole lot in other events, but there weren’t too many other cases of tornadoes that intense moving that quickly.
Yes, I have seen the video you're talking about although IIRC it's not from as close as the above photo and there are a lot of trees in the way.

You are correct; horizontal vortex tubes and top part of funnel tilt in the direction of motion are two things frequently observed on days with strong upper-level winds (fast storm motion) and very strong low-level shear, both of which favor violent tornado outbreaks. Those features were common in all of the Super Outbreaks and near-Super Outbreaks to occur since tornado imagery became commonplace (1974, 2011 and Palm Sunday 1965).

Tornadoes that occur on high-end outbreak days seem to be a different animal than other tornadoes, aside from the horizontal vortex tubes they also often exhibit very rapid changes in appearance/size. Chaotic/amorphous multivortex phases (often described by lay observers as "tentacles" or some such) quickly followed by violently rotating stovepipe/barrel occasionally with satellite tornado(es) followed by enormous mile-wide wedge (and sometimes then back to multivortex) seems to be a common sequence.
 
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warneagle

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Yeah, I’ve always been fascinated by how tornadoes in major outbreaks demonstrate the extreme atmospheric conditions—and not always in the same way (like the horizontal vortices on April 27th or the multiple double tornadoes in the Palm Sunday 1965 outbreak).

Another thing I’ve thought about from April 27th that might make a good research topic was some of the extreme ground scouring (especially the Philadelphia tornado). Like, whether that area was particularly predisposed to being scoured because of the soil conditions or whether there was a unique feature in that tornado (and some of the others) that produced that kind of effect independently of soil composition, etc. I think studying that has some useful practical applications. Even though ground scouring is a less “traditional” damage indicator than buildings or vegetation, it’s certainly a feature that’s unique to the most violent tornadoes and might tell us something about the relative intensity of those events.

There are probably dozens of physics and atmospheric science dissertations that could be written about this outbreak. It’s hard to get your head around such an extreme event.
 
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Weatherphreak

Member
Messages
84
Location
Huntsville
Hard to believe it’s been 8 years. I still watch the YouTube coverage from that day with Spann from time to time. I was working in Arab and living in Huntsville at that time and had no clue what had happened in others parts of the state after the Cullman EF4 went through Arab just north of me. I went to work the next morning and turned on our battery operated radio and started to hear the reports of Birmingham and Tuscaloosa. I had no clue the gravity of the situation. I feel like the NE Alabama tornadoes get forgotten. That Rainsville tornado was just as strong as the other EF5s but gets very few mentions. The scars they gave the landscape are slowly disappearing. Driving to talladega this weekend the Ohatachee and Arab paths were barely detectable anymore.
 
Messages
347
Location
Niagara Falls, Ontario
Another thing I’ve thought about from April 27th that might make a good research topic was some of the extreme ground scouring (especially the Philadelphia tornado). Like, whether that area was particularly predisposed to being scoured because of the soil conditions or whether there was a unique feature in that tornado (and some of the others) that produced that kind of effect independently of soil composition, etc. I think studying that has some useful practical applications. Even though ground scouring is a less “traditional” damage indicator than buildings or vegetation, it’s certainly a feature that’s unique to the most violent tornadoes and might tell us something about the relative intensity of those events.
I've wondered about this myself. Some folks have pointed out that Neshoba and Kemper Counties got a lot of rain in the days leading up to the outbreak which might have compromised the soil a bit, but Monroe County had even heavier rainfall in the same time, and the ground scouring from the Smithville tornado was quite a bit less intense than the Philadelphia tornado.

I'm not sure what caused the deep trenches in Neshoba County. Maybe the dense row of trees the tornado's core passed between had a wind tunnel effect and accelerated the ground-level winds? Hard to say.
 

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