UH OH. JAN DISCUSSION VERY SCARRY! TORANDO OUTBREAK!!!!

[Wnghs2007]

JAN Afternoon Discussion:

HEADLINE...TORNADO OUTBREAK POSSIBLE TUESDAY AND TUESDAY NIGHT.
DETAILS FOLLOW.

&&

.SYNOPSIS...STRIKINGLY GOOD AGREEMENT EXISTS BETWEEN THE MAJOR
COMPUTER MODELS IN BOTH THE TIMING...INTENSITY AND TRACK OF THE
UPCOMING SYSTEM. IN ADDITION...THE GFS HAS EXHIBITED GOOD RUN TO RUN
CONSISTENCY. THEREFORE CONFIDENCE IS FAIRLY HIGH WITH THIS
SYSTEM...DESPITE IT BEING 3 AND 1/2 DAYS AWAY.

&&
.LONG TERM...TUESDAY AND BEYOND. EVERY SINGLE SEVERE WEATHER
PARAMETER SUGGESTS THAT THERE IS GOOD POTENTIAL FOR SIGNIFICANT
ORGANIZED SEVERE CONVECTIVE ACTIVITY ON TUESDAY. DUE TO THE TIMING
OF PASSAGE OF THIS SYSTEM (WHICH IS DURING THE LATE
AFTERNOON)...APPEARS THAT IT WILL BE ABLE TO UTILIZE THE DAILY
HEATING (THOUGH THE HEATING SHOULD BE SOMEWHAT LIMITED BY CLOUD
COVER.) WARM AIR AND MOISTURE TRANSPORT INTO THE REGION FROM THE
GULF WILL BE QUITE STRONG DURING THIS PERIOD. THIS SHOULD HELP
INCREASE AND MAINTAIN THE INSTABILITY OVER THE AREA. THE SHEAR
PROFILES ARE EXPECTED TO BECOME STRONGER AS A 60 KT SOUTHERLY LOW
LEVEL JET MOVES OVER THE AREA AND AS 80 KT SOUTHWESTERLY MID LEVEL
JET POSITIONS ITSELF OVER ARKANSAS LATE TUESDAY AFTERNOON.
FURTHERMORE...THE ARK-LA-MISS WILL BE UNDERNEATH A COUPLED UPPER
LEVEL JET (IN THE RIGHT...ENTRANCE QUADRANT OF ONE AND IN THE
LEFT...EXIT QUADRANT OF ANOTHER.) THIS POSITIONING OF THE JETS OVER
THE AREA SHOULD SIGNIFICANTLY HELP THE CONVECTIVE DEVELOPMENT.
ADDITIONAL LIFT WILL COME IN THE FORM OF AN EXTREMELY WELL DEFINED
COLD FRONTAL BOUNDARY. TIME HIGHT PLOTS SHOW A RADICAL CHANGE IN
AIRMASSES. THOUGH THE POST FRONTAL AIRMASS WILL NOT BE VERY
COLD...IT WILL BE EXTREMELY DRY. THIS IS IN STARK CONTRAST TO THE
MOIST AIRMASS AHEAD OF THE FRONT. SPEAKING OF THE "WETNESS" OF THIS
SYSTEM...THERE SHOULD BE SOME FLOODING CONCERNS ARISING TUESDAY
AFTERNOON AS THE MAIN SYSTEM MOVES THROUGH. EVENT TOTAL
PRECIPITATION AMOUNTS COULD BE NEAR 10 INCHES IN A FEW LOCATIONS
WITH 4 TO 5 INCHES FALLING IN SOME AREAS DURING THE MAIN EVENT ON
TUESDAY AND TUESDAY NIGHT. (THE LARGE EVENT TOTAL IS FOR THE PERIOD
TONIGHT THROUGH TUESDAY NIGHT.)

DESPITE THE CONCERN FOR SOME FLOODING...THE SEVERE THUNDERSTORM
POTENTIAL REMAINS THE MAIN CONCERN. EARLY INDICATORS SHOW A
SIGNIFICANT CONCERN FOR TORNADIC ACTIVITY ALONG WITH STRAIGHT LINE
WINDS. GIVEN THE HIGHLY FAVORABLE DYNAMIC STATE OF THE
ATMOSPHERE...SOME OF THE TORNADOES COULD BE QUITE STRONG. IF THE
CURRENT MODEL SOLUTIONS HOLD...WHICH THEY SHOULD...WE ARE EXPECTING
THE DEVELOPMENT OF SUPERCELLS (SOME TORNADIC) OUT AHEAD OF A
LARGE...STRONG SQUALL LINE THAT SHOULD MOVE FROM WEST TO EAST ACROSS
THE AREA MONDAY AND MONDAY NIGHT. THE MAIN CONCERNS WITH THE
SUPERCELLS SHOULD BE FOR TORNADOES AND HAIL. THE MAIN CONCERNS WITH
THE SQUALL LINE SHOULD BE FOR STRAIGHT LINE WINDS AND ISOLATED
TORNADOES.

[PurdueWx80]

Excellent discussion..not too different than what myself and others have been saying in another post. The fact that the model solutions continue to paint a highly volatile situaiton that this is gonna happen. It will all be a matter of timing, if the shortwave ejects out of the SW too slowly (which I don't believe) the front will be coming through Tuesday night, which tells me there'd be somewhat of a smaller chance of tornadic storms (but still a high threat for a squall line). This is going to be a VERY interesting week weather-wise.

[Guest]

It will all be a matter of timing, if the shortwave ejects out of the SW too slowly (which I don't believe) the front will be coming through Tuesday night, which tells me there'd be somewhat of a smaller chance of tornadic storms (but still a high threat for a squall line).

A smaller chance of tornadic storms, but not by much. I heard somewhere that nighttime tornado outbreaks are more common in that part of the country, which doubles their deadly potential.

Folks in the SE: Make sure you have a good-working NOAA Weather radio for the middle of the night; come next week, it will be a God-send.

[MGC]

Yep, conditions appear right for a southern outbreak. November is tornado season for the gulf states......MGC

[SouthernWx]

Intense nighttime tornadoes are not uncommon in the southeastern states during November...

Just think back to November 23-24, 2001....when several large F3 and F4 tornadoes tore across Mississippi between midnight and 5 a.m....one near Madison, MS killed two and injured 150....leveled a subdivision of nearly new, large, well built brick homes (my former EDS supervisor's home was one that was badly damaged).

On November 21, 1992...two large and extremely powerful tornadoes ripped across Mississippi after midnight; the first killed 12 in Brandon...it was on the ground for 130 miles and 1/2-3/4 mile wide. A second farther south was on the ground for 40 miles and at times over a mile wide...fortunately this 250 mph monster mostly struck rural areas...no one was killed.

This storm has the potential to be just as intense and destructive...or even worse; as the Jackson forecaster stated....all parameters for a tornado outbreak are forecast to occur...and the models are in very good agreement (ETA slightly faster than the GFS).

The November 21-23, 1992 tornadic swarm is the largest of record for this month...92 tornadoes (26 dead, six F4's...over a dozen F3's), all the way from Houston, TX to central Indiana to Elizabeth City, NC. This could be as bad or even worse....the upper air and surface progs remind me of both the November 1992 outbreak...and the April 3, 1974 superoutbreak (same type of extreme diffluent upper jet pattern....if we get enough surface instability over a large area ahead of the bombing surface low/ strong cold front, there may be some records set

[MGC]

I pray that this event don't come close to the Nov 92 outbreak. The F-4 that went through Brandon was horrible. The tornado occured before the doppler radar was installed at Jackson. The tornado was completely masked by precipitation and went undetected by radar. No warning were issued untill the storm was a killer. The damage along its path was total. The damage was almost as bad as the May 99 tornado in Oklahoma City. I was in OKC a month after the twister and comparing the two I'm surprised the Brandon twister was not an F-5. Houses were scraped clean to the slab just like in OKC......MGC

[WXBUFFJIM]

Just checked the latest models and they're all in agreement that this could be a big one, especially for southern Arkansas, Mississippi, and parts of Tennessee Tuesday evening. Conditions dymanicly appear very favorable for tornadoes, some strong. My concern is possibly this event occurring late into the night Tuesday into early Wednesday morning. Some of the worse tornadoes in the southeast states as seen in recent history have occurred at night. Take Camilla, Georgia as a classic example.

Hopefully this won't come true, but we need to keep a close eye on it as the southeastern states are no strangers to tornadoes in November.

[Anonymous]

I hope not. They don't need anymore tornadoes in the South, or anywhere else for that matter.


-Jeb

[SouthernWx]

MGC, both the Brandon and Sylvania tornadoes in 1992 were close to F5 intensity (IMO 250 mph at their peak). I have relatives in the Jackson area (and lived in southern Madison county myself during 1995-96), and saw the damage up close...it was horrendous.

[yoda]

Morning AFD's from areas in possible SVR WX OTBRK areas seem to be more focused on a squall line and DMG WND threat than tornadoes.

[Wnghs2007]

Morning AFD's from areas in possible SVR WX OTBRK areas seem to be more focused on a squall line and DMG WND threat than tornadoes.

Yep. Still to early to tell, they dont want to go all out on possible TOR Outbreak yet, but they will soon enough. These solutions coming from the models are very concerning. Especially over Mississpi/Alabama areas. Dryslot on models. Which would allow for breaks in the clouds and any bit of sun will make the instability higher. And looks like Dwpts in the 70's and Temps into the 80's pssbl. Very active time coming. And they better be prepared to seek shelter. Should this event continue to look like it could potentail be a Tornado Outbreak.

[yoda]

Limited instability appears to be the problem, and may help out in the long run here...

[yoda]

New morning AFD from JAN looks...

FOR THIS MAIN SYSTEM...NOTHING MUCH HAS CHANGED. IF ANYTHING THE
NEWER MODEL RUNS ARE TRENDING STRONGER AND A BIT FURTHER SOUTH!!
WHAT I AM EXPECTING IS A SQUALL LINE TO DEVELOP ALONG THE PREFRONTAL
TROUGH AND RAPIDLY SHIFT EAST AS THE MID-LEVEL JET (60-75KTS) AND
UPPER JET (110-120KTS) OVERSPREAD THE WARM SECTOR. THIS LINE WILL
LIKELY CONTAIN BOWING SEGMENTS AND HIGH POTENTIAL OF DAMAGING WINDS
AS WELL AS SOME POTENTIAL FOR SIG WIND (>65KTS)! OF GREATER CONCERN
WILL BE IF ANY SUPERCELLS CAN DEVELOP AHEAD OF THE LINE. AT THIS
TIME...IT SEEMS VERY LIKELY THERE WILL BE SOME! THESE WILL POSE THE
MOST SIG THREAT WITH ANY ONE OF THEM CONTAINING LARGE HAIL AND
TORNADOES. DUE TO THE KINEMATICS OF THIS SYSTEM AND THE STRONG WIND
SHEAR THAT WILL BE IN PLACE...THE POTENTIAL EXISTS FOR ANY SUPERCELL
TO PRODUCE A STRONG TORNADO! THE MAIN THING TO FOCUS ON IS THAT THIS
IS ALL ABOUT PATTERN RECOGNITION AND IF WHAT THE MODELS SHOW
ACTUALLY OCCURS! HOWEVER...DUE TO THE VERY CONVINCING CONSISTENCY
THE PAST 4 DAYS...CONFIDENCE IS HIGH THAT SOMETHING WILL OCCUR TO
THE EXTENT I JUST DESCRIBED!

[yoda]

http://www.srh.noaa.gov/jan/cgi-bin/pro ... &version=0

[SouthernWx]

http://www.srh.noaa.gov/jan/cgi-bin/productview2.php?pil=JANAFDJAN&version=0

And that's a very good forecast office (KJAN)....and usually tend to be conservative regarding potential severe wx events.

The fact there's such excellent model consensus, and has been for several days only adds confidence and concern this could be a widespread and potentially devastating tornado outbreak; not only in Mississippi...but IMO from southeast Texas and and Lousiana as far north as Kentucky and southern Indiana/ Ohio...and as far east as the Carolinas; but I expect particularly intense tornadoes in the Mississippi/ Alabama/ western Tennessee area.

The model guidance also suggest a couple waves of intense storms late Tuesday/ Tue night...with the final massive and violent squall line capable of extreme and widespread wind damage as it roars across the south.

[Stormsfury]

The air is already plenty juicy as evidenced from the first s/w right now impacting Southeast TX with locations coming in with as much as 15" just today ...

the s/w and associated 500mb low in California right now is extremely potent ... and I expect from healthy storm totals to come in from out west (CA, AZ) and as this meets up with deep moisture ... LOOK OUT ...

[Brent]

[yoda]

But wait, could we be seeing the worst come at night?

JAN AFD, 5:15 AM EST... TODAY

AFTER 36 HOURS...MUCH HAS BEEN WRITTEN IN THE PAST FEW AFDS ABOUT
THE POTENTIAL FOR SEVERE WEATHER TUESDAY INTO TUESDAY NIGHT SO I
WILL NOT ELABORATE TOO MUCH...ESPECIALLY SINCE MODEL FORECASTS ARE
NOT WAVERING MUCH. THE ONE ASPECT THAT WAS CHANGED WAS TO SLOW DOWN
THE PROGRESS OF THE MAJOR UPPER DISTURBANCE AND ASSOCIATED FRONT
THAT WILL MOVE ACROSS AND TRIGGER THE POTENTIAL OUTBREAK. THE
PREVIOUS FORECAST FOCUSED ON THE TUESDAY INTO TUESDAY EVENING TIME
FRAME...BUT MODEL TRENDS ARE BECOMING MORE INSISTENT THAT THE EVENT
WILL COME TUESDAY EVENING INTO EARLY WEDNESDAY MORNING. THAT
SAID...THERE WILL STILL BE SOME...ALBEIT MORE LIMITED...POTENTIAL
FOR SEVERE WEATHER STARTING DAYTIME TUESDAY IN CENTRAL AND SOUTHERN
ZONES. ADDITIONALLY...THE GRADUAL TREND OF THE MODELS TO SHIFT THE
TRACK OF THE DISTURBANCE FURTHER SOUTH LEADS ME TO BELIEVE THE
GREATEST OVERALL RISK OF SEVERE WEATHER MAY BE FOCUSED ALONG AND
SOUTH OF THE I-20 CORRIDOR. STILL LOOKS LIKE ALL MODES OF SEVERE
WEATHER WILL BE POSSIBLE WITH SHEAR PARAMETERS AT LEAST TEMPORARILY
SUPPORTIVE OF SIGNIFICANT TORNADOES. LAST...BUT NOT LEAST...WILL BE
THE POTENTIAL FOR FLOODING AS ANOTHER 2-4 INCHES OF PRECIPITATION IS
POSSIBLE DURING THE EVENT. BY THIS TIME SUCH AMOUNTS SHOULD BE
ENOUGH TO CAUSE AT LEAST ISOLATED FLOODING PROBLEMS. FUTURE SHIFTS
MAY HAVE TO CONTEMPLATE A FLOOD WATCH. ALL OF THIS IS HIGHLIGHTED IN
THE HWO.

Not to takeaway from the severity of the threat, but wouldn't this help some?


http://www.srh.noaa.gov/jan/cgi-bin/pro ... &version=0

[TexasStooge]

And it looks like the Northern part of Texas is next tomorrow.

[Fred Gossage]

But wait, could we be seeing the worst come at night?

JAN AFD, 5:15 AM EST... TODAY

AFTER 36 HOURS...MUCH HAS BEEN WRITTEN IN THE PAST FEW AFDS ABOUT
THE POTENTIAL FOR SEVERE WEATHER TUESDAY INTO TUESDAY NIGHT SO I
WILL NOT ELABORATE TOO MUCH...ESPECIALLY SINCE MODEL FORECASTS ARE
NOT WAVERING MUCH. THE ONE ASPECT THAT WAS CHANGED WAS TO SLOW DOWN
THE PROGRESS OF THE MAJOR UPPER DISTURBANCE AND ASSOCIATED FRONT
THAT WILL MOVE ACROSS AND TRIGGER THE POTENTIAL OUTBREAK. THE
PREVIOUS FORECAST FOCUSED ON THE TUESDAY INTO TUESDAY EVENING TIME
FRAME...BUT MODEL TRENDS ARE BECOMING MORE INSISTENT THAT THE EVENT
WILL COME TUESDAY EVENING INTO EARLY WEDNESDAY MORNING. THAT
SAID...THERE WILL STILL BE SOME...ALBEIT MORE LIMITED...POTENTIAL
FOR SEVERE WEATHER STARTING DAYTIME TUESDAY IN CENTRAL AND SOUTHERN
ZONES. ADDITIONALLY...THE GRADUAL TREND OF THE MODELS TO SHIFT THE
TRACK OF THE DISTURBANCE FURTHER SOUTH LEADS ME TO BELIEVE THE
GREATEST OVERALL RISK OF SEVERE WEATHER MAY BE FOCUSED ALONG AND
SOUTH OF THE I-20 CORRIDOR. STILL LOOKS LIKE ALL MODES OF SEVERE
WEATHER WILL BE POSSIBLE WITH SHEAR PARAMETERS AT LEAST TEMPORARILY
SUPPORTIVE OF SIGNIFICANT TORNADOES. LAST...BUT NOT LEAST...WILL BE
THE POTENTIAL FOR FLOODING AS ANOTHER 2-4 INCHES OF PRECIPITATION IS
POSSIBLE DURING THE EVENT. BY THIS TIME SUCH AMOUNTS SHOULD BE
ENOUGH TO CAUSE AT LEAST ISOLATED FLOODING PROBLEMS. FUTURE SHIFTS
MAY HAVE TO CONTEMPLATE A FLOOD WATCH. ALL OF THIS IS HIGHLIGHTED IN
THE HWO.

Not to takeaway from the severity of the threat, but wouldn't this help some?


http://www.srh.noaa.gov/jan/cgi-bin/pro ... &version=0

Since this has been compared to the November 21-23, 1992 event.....I thought I would throw out the point that an event coming in during the overnight does not always mean it will be less significant... Take those two F4 MS tornadoes in that 1992b event for example. See, if dewpoints get into the lower 70s, it's rather difficult to get them back down without a front actually sweeping them out. And we all know that the temperature has to be at or higher than the dewpoint, which means...in that case...they wouldn't be in the 60s. Couple that with 500-mb temps of -14 C approaching rapidly from the west....and the instability really doesn't diminish all that much after dark south of the warm front.