February 5-6: Super Tuesday Outbreak... 57 dead

[icicle]

If this stays on track, I wouldnt be at all surprised to see a mod risk issued tomorrow for tuesday.
I do wonder though if they'll go a step farther than that.

[CrazyC83]

Looks like a good shot at a MDT for Day 2 tomorrow. Surprisingly conservative for tomorrow night, I figured they'd have a larger SLGT area with a 30% or hatched 30% in there (although too much uncertainty for a MDT)...

[Extremeweatherguy]

It looks like the SPC may be slowing down the timing and shifting the threat area further south than previously expected.

Their latest Day 2 outlook now moves the slight risk area for tomorrow further southwest and digs it deeper into Texas....

Previous Day 2 outlook: http://www.spc.noaa.gov/products/outloo ... _0800.html

New Day 2 outlook: http://www.spc.noaa.gov/products/outlook/day2otlk.html

What this means is that the squall line may try to set itself up and become better established sooner than previously predicted..possibly leading to a more widespread severe event, even in places further west. Late Monday through Tuesday is definitely looking interesting, that's for sure, and this could wind up being a pretty widespread event for February.

[MiamiensisWx]

Cells will likely be discrete because of 1) the low's motion and 2) the lack of linear forcing. If shear is too strong while surface winds are backed ("backed" implies westerly winds), the discrete supercells would eventually evolve into a broken or continuous squall line. Squall lines would also reduce instability ahead of the surface boundary, thus reducing the tornado threat. In this case, there is a large warm sector with decent THETA-E ahead of the boundary. The progged 500 mb ridge juxtaposition and consolidated trough also ensures adequate low-level moisture return. A large dry slot would also cap convection (in addition to less lift) over the northern Gulf, which allows an uncontaminated "return flow" and higher 12-hour maximum temps well into the Mississippi Valley. Winds will likely be veered (S or SSE) in this case, which also heightens the threat. Even closer to the low, the lack of linear forcing would likely support strong discrete cells with backed (WSW) winds.

THETA-E link:

http://www.theweatherprediction.com/habyhints/324/

Linear forcing:

http://meetings.aps.org/Meeting/DFD05/Event/36922

Umm... why did no one appreciate my response?!

I guess you are ignored if you aren't a met...

[RL3AO]

Cells will likely be discrete because of 1) the low's motion and 2) the lack of linear forcing. If shear is too strong while surface winds are backed ("backed" implies westerly winds), the discrete supercells would eventually evolve into a broken or continuous squall line. Squall lines would also reduce instability ahead of the surface boundary, thus reducing the tornado threat. In this case, there is a large warm sector with decent THETA-E ahead of the boundary. The progged 500 mb ridge juxtaposition and consolidated trough also ensures adequate low-level moisture return. A large dry slot would also cap convection (in addition to less lift) over the northern Gulf, which allows an uncontaminated "return flow" and higher 12-hour maximum temps well into the Mississippi Valley. Winds will likely be veered (S or SSE) in this case, which also heightens the threat. Even closer to the low, the lack of linear forcing would likely support strong discrete cells with backed (WSW) winds.

THETA-E link:

http://www.theweatherprediction.com/habyhints/324/

Linear forcing:

http://meetings.aps.org/Meeting/DFD05/Event/36922

Umm... why did no one appreciate my response?!

I guess you are ignored if you aren't a met...

I read it and checked out your links. I just didn't respond. Maybe it had too many big words?

[HarlequinBoy]

Cells will likely be discrete because of 1) the low's motion and 2) the lack of linear forcing. If shear is too strong while surface winds are backed ("backed" implies westerly winds), the discrete supercells would eventually evolve into a broken or continuous squall line. Squall lines would also reduce instability ahead of the surface boundary, thus reducing the tornado threat. In this case, there is a large warm sector with decent THETA-E ahead of the boundary. The progged 500 mb ridge juxtaposition and consolidated trough also ensures adequate low-level moisture return. A large dry slot would also cap convection (in addition to less lift) over the northern Gulf, which allows an uncontaminated "return flow" and higher 12-hour maximum temps well into the Mississippi Valley. Winds will likely be veered (S or SSE) in this case, which also heightens the threat. Even closer to the low, the lack of linear forcing would likely support strong discrete cells with backed (WSW) winds.

THETA-E link:

http://www.theweatherprediction.com/habyhints/324/

Linear forcing:

http://meetings.aps.org/Meeting/DFD05/Event/36922

Umm... why did no one appreciate my response?!

I guess you are ignored if you aren't a met...

I read it and checked out your links. I just didn't respond. Maybe it had too many big words?

I too read it, I just didn't have anything to add.

[HarlequinBoy]

Jackson HWO
.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A POTENTIALLY SIGNIFICANT AND WIDESPREAD SEVERE WEATHER EVENT IS
POSSIBLE ON TUESDAY. INSTABILITY AND WIND FIELDS WILL BE SUFFICIENT
TO SUPPORT DAMAGING WINDS...LARGE HAIL AND TORNADOES. THIS ACTIVITY
IS EXPECTED AHEAD OF A COLD FRONT THAT WILL MOVE ACROSS THE AREA
TUESDAY NIGHT.

Memphis HWO
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MONDAY AFTERNOON
INTO MONDAY NIGHT...MAINLY ALONG AND WEST OF A LINE FROM UNION
CITY TENNESSEE TO HOLLY SPRINGS MISSISSIPPI TO CHARLESTON
MISSISSIPPI. UNSEASONABLY WARM...MOIST AND UNSTABLE AIR WILL PUSH
INTO THE AREA MONDAY AND MONDAY NIGHT ON INCREASING SOUTH WINDS.
SCATTERED THUNDERSTORMS ARE EXPECTED WITH A FEW POSSIBLY SEVERE.
THE MAIN THREAT WILL BE DAMAGING WINDS AND LARGE HAIL...ALTHOUGH
ISOLATED TORNADOES CAN NOT BE RULED OUT.

THERE IS THE POTENTIAL FOR A WIDESPREAD SEVERE WEATHER OUTBREAK
ACROSS THE MID-SOUTH TUESDAY. A STRONG COLD FRONT WILL MOVE INTO
THE AREA FROM THE WEST TUESDAY COLLIDING WITH THE UNSEASONABLY
WARM...MOIST AND UNSTABLE AIR IN PLACE. DAMAGING WINDS AND LARGE
HAIL ARE POSSIBLE ALONG WITH THE THREAT OF TORNADOES.
MID-SOUTHERNERS SHOULD KEEP TOUCH WITH THE LATEST FORECASTS
CONCERNING THE SEVERE WEATHER POTENTIAL TUESDAY.

A WIND ADVISORY WILL LIKELY BE NEEDED TUESDAY. SOUTH WINDS ARE
FORECAST AROUND 25 MPH WITH GUSTS UP TO AROUND 40 MPH.


On another note, I can't believe it's going to be in the 70s tomorrow and Tuesday!

[Squarethecircle]

I have a bad feeling about this. I don't know why, but when there are reports like this out and the various weather stations don't even mention severe potential, it starts to scare me. The only thing out on the maps are red areas with thunderbolts on NBC. They said there's no chance of anything like that impacting Super Tuesday. That just kinda freaks me out, you know?

[wxmann_91]

Cells will likely be discrete because of 1) the low's motion and 2) the lack of linear forcing. If shear is too strong while surface winds are backed ("backed" implies westerly winds), the discrete supercells would eventually evolve into a broken or continuous squall line. Squall lines would also reduce instability ahead of the surface boundary, thus reducing the tornado threat. In this case, there is a large warm sector with decent THETA-E ahead of the boundary. The progged 500 mb ridge juxtaposition and consolidated trough also ensures adequate low-level moisture return. A large dry slot would also cap convection (in addition to less lift) over the northern Gulf, which allows an uncontaminated "return flow" and higher 12-hour maximum temps well into the Mississippi Valley. Winds will likely be veered (S or SSE) in this case, which also heightens the threat. Even closer to the low, the lack of linear forcing would likely support strong discrete cells with backed (WSW) winds.

THETA-E link:

http://www.theweatherprediction.com/habyhints/324/

Linear forcing:

http://meetings.aps.org/Meeting/DFD05/Event/36922

No, backing of winds with time is when the wind direction trends counterclockwise with time (in this case, it would be when the wind direction is NOT from the west).

[HarlequinBoy]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
256 PM CST SUN FEB 3 2008

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-041200-
ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER-
FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY-
ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON-
MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT-
PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY-
ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA-
UNION-WEAKLEY-YALOBUSHA-
INCLUDING THE CITIES OF...ABERDEEN...AMORY...BARTLETT...
BATESVILLE...BLYTHEVILLE...BOLIVAR...BOONEVILLE...
CARUTHERSVILLE...CLARKSDALE...COLLIERVILLE...CORINTH...
COVINGTON...DRESDEN...DYERSBURG...FORREST CITY...GERMANTOWN...
HARRISBURG...HELENA...HUMBOLDT...HUNTINGDON...IUKA...JACKSON...
JONESBORO...KENNETT...LEXINGTON...MARTIN...MEMPHIS...MILAN...
MILLINGTON...NEW ALBANY...OLIVE BRANCH...OXFORD...PARAGOULD...
PARIS...SAVANNAH...SOMERVILLE...SOUTHAVEN...TUNICA...TUPELO...
UNION CITY...WALNUT RIDGE...WEST MEMPHIS...WYNNE
256 PM CST SUN FEB 3 2008

...MAJOR SEVERE WEATHER OUTBREAK POSSIBLE ACROSS THE MIDSOUTH
TUESDAY AFTERNOON AND EVENING...

A STRONG COLD FRONT WILL MOVE INTO THE MIDSOUTH BEGINNING TUESDAY
AFTERNOON. THE FRONT WILL COLLIDE WITH A UNSEASONABLY WARM...MOIST
AIR MASS THAT WILL BE IN PLACE OVER THE REGION. THIS COMBINATION WILL
PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE AREA.
THUNDERSTORMS THAT DEVELOP WILL LIKELY BECOME SEVERE FAIRLY QUICKLY.
THE MAIN THREATS FROM THE SEVERE STORMS WILL BE DAMAGING
WINDS...LARGE HAIL...AND POSSIBLE TORNADOES. THE BEST TIMING FOR THE
SEVERE WEATHER WILL BE BETWEEN 1 PM AND 9 PM CDT. PLEASE STAY
INFORMED WITH THE LATEST FORECASTS CONCERNING THE SEVERE WEATHER
POTENTIAL TUESDAY AFTERNOON AND EVENING.


The NWS office here seems pretty concerned/confident about this outbreak, so we'll see. Local media isn't mentioning anything other than "showers and thunderstorms" yet.

[HarlequinBoy]

THE CWA WILL ALSO BE IN THE
RIGHT ENTRANCE REGION OF AN 140 KT UPPER LEVEL JET.

What exactly is that?

[icicle]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
256 PM CST SUN FEB 3 2008

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-041200-
ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER-
FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY-
ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON-
MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT-
PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY-
ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA-
UNION-WEAKLEY-YALOBUSHA-
INCLUDING THE CITIES OF...ABERDEEN...AMORY...BARTLETT...
BATESVILLE...BLYTHEVILLE...BOLIVAR...BOONEVILLE...
CARUTHERSVILLE...CLARKSDALE...COLLIERVILLE...CORINTH...
COVINGTON...DRESDEN...DYERSBURG...FORREST CITY...GERMANTOWN...
HARRISBURG...HELENA...HUMBOLDT...HUNTINGDON...IUKA...JACKSON...
JONESBORO...KENNETT...LEXINGTON...MARTIN...MEMPHIS...MILAN...
MILLINGTON...NEW ALBANY...OLIVE BRANCH...OXFORD...PARAGOULD...
PARIS...SAVANNAH...SOMERVILLE...SOUTHAVEN...TUNICA...TUPELO...
UNION CITY...WALNUT RIDGE...WEST MEMPHIS...WYNNE
256 PM CST SUN FEB 3 2008

...MAJOR SEVERE WEATHER OUTBREAK POSSIBLE ACROSS THE MIDSOUTH
TUESDAY AFTERNOON AND EVENING...

A STRONG COLD FRONT WILL MOVE INTO THE MIDSOUTH BEGINNING TUESDAY
AFTERNOON. THE FRONT WILL COLLIDE WITH A UNSEASONABLY WARM...MOIST
AIR MASS THAT WILL BE IN PLACE OVER THE REGION. THIS COMBINATION WILL
PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE AREA.
THUNDERSTORMS THAT DEVELOP WILL LIKELY BECOME SEVERE FAIRLY QUICKLY.
THE MAIN THREATS FROM THE SEVERE STORMS WILL BE DAMAGING
WINDS...LARGE HAIL...AND POSSIBLE TORNADOES. THE BEST TIMING FOR THE
SEVERE WEATHER WILL BE BETWEEN 1 PM AND 9 PM CDT. PLEASE STAY
INFORMED WITH THE LATEST FORECASTS CONCERNING THE SEVERE WEATHER
POTENTIAL TUESDAY AFTERNOON AND EVENING.


The NWS office here seems pretty concerned/confident about this outbreak, so we'll see. Local media isn't mentioning anything other than "showers and thunderstorms" yet.

my local mets are mentioning it, big time.

[Ed Mahmoud]

IIRC, left exit, right and right entrance (nice diagram is Koscin and Ucellini book) are upward motion regions of the jet. Unless I remember it 180º backwards/

[Ed Mahmoud]

OK, the equations bear an uncomfortable resemblance to the diffusivity equation that petroleum engineers have to learn, before forgetting, but skimming past the scientific discussion

I can't copy the images here, but there are helpful pictures.

From this diagram it is seen that the ageostrophic wind is divergent in the right-entrance and left-exit regions of the jet streak, and convergent in the other regions (see diagram below). This leads to upward motion in the right-entrance and left-exit regions of the jet streak.

Link

[Ed Mahmoud]

MARDI GRAS TORNADO OUTBREAK?

FXUS64 KLIX 032133
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
333 PM CST SUN FEB 3 2008

.DISCUSSION
MAIN FORECAST CONCERN CENTERS AROUND CONVECTION EXPECTED TUESDAY
AFTERNOON AND TUESDAY NIGHT.
...snip...
MODELS HAVE REMAINED QUITE CONSISTENT WITH EACH OTHER AND WITH
THE TIMING OF THE UPPER TROUGH NOW IMPACTING THE WEST COAST AS IT
TRAVERSES THE WESTERN U.S. AND MOVES ACROSS THE MID SECTION OF THE
COUNTRY AND THE MISSISSIPPI VALLEY TUESDAY AND TUESDAY NIGHT. AT
THIS TIME IT LOOKS AS IF MOST OF THE CONVECTION WILL HOLD OFF
UNTIL LATE TUESDAY AND TUESDAY NIGHT...ALTHOUGH THE WESTERN ZONES
WILL SEE MORE IN THE WAY OF COVERAGE TUESDAY AFTERNOON. SOME OF THIS
CONVECTION COULD BE STRONG TO SEVERE FROM LATE TUESDAY AFTERNOON
THROUGH TUESDAY EVENING. THE ASSOCIATED COLD FRONT WILL MOVE
ACROSS THE ENTIRE FORECAST AREA TUESDAY NIGHT.

[RL3AO]

My predictions for 6z
Day 1: 5% T, 15% W, 30% H = slight
Day 2: 45% moderate

[HarlequinBoy]

The NWS office here seems pretty concerned/confident about this outbreak, so we'll see. Local media isn't mentioning anything other than "showers and thunderstorms" yet.

my local mets are mentioning it, big time.

What stations do you watch? But the Memphis stations were really mentioning it on the evening newscast.

[HarlequinBoy]

OK, the equations bear an uncomfortable resemblance to the diffusivity equation that petroleum engineers have to learn, before forgetting, but skimming past the scientific discussion

I can't copy the images here, but there are helpful pictures.

From this diagram it is seen that the ageostrophic wind is divergent in the right-entrance and left-exit regions of the jet streak, and convergent in the other regions (see diagram below). This leads to upward motion in the right-entrance and left-exit regions of the jet streak.

Link

Ah, thanks.. I think I got it now. A tad over my head. hehe

And I renamed the thread.

[Cyclenall]

If a tornado outbreak occurs, they should name it The Super Tuesday Super Tornado Outbreak.

[CrazyC83]

My predictions for 6z
Day 1: 5% T, 15% W, 30% H = slight
Day 2: 45% moderate

My guesses:

Day 1 - 10% tornado, 30%-H wind, 30% hail - SLGT (potential for MDT later)

Day 2 - 45%-H overall - MDT