Big Severe Wx Outbreak around 10/18/07 in Plains

[Brent]

Something of interest heading into the Tuscaloosa, Alabama area.

WWUS54 KBMX 182242
SVSBMX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
542 PM CDT THU OCT 18 2007

ALC125-182315-
/O.CON.KBMX.TO.W.0145.000000T0000Z-071018T2315Z/
TUSCALOOSA AL-
542 PM CDT THU OCT 18 2007

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 615 PM CDT FOR CENTRAL
TUSCALOOSA COUNTY...

AT 542 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A TORNADO. THIS TORNADO WAS LOCATED 10 MILES SOUTH OF
COKER...OR ABOUT 13 MILES SOUTHWEST OF NORTHPORT...MOVING NORTHEAST
AT 15 MPH.

THE TORNADO WILL BE NEAR...
9 MILES SOUTHEAST OF BUHL BY 555 PM CDT...
6 MILES SOUTHEAST OF COKER BY 610 PM CDT...
OLIVER LOCK DAM...OLIVER LOCK AND DAM...TUSCALOOSA MUNICIPAL
AIRPORT AND NORTHPORT BY 615 PM CDT...

IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A NEARBY REINFORCED
BUILDING. AS A LAST RESORT...SEEK SHELTER IN A CULVERT...DITCH OR LOW
SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

LAT...LON 3332 8771 3333 8756 3320 8744 3312 8757
3306 8771 3306 8774 3308 8776 3320 8783
TIME...MOT...LOC 2242Z 241DEG 14KT 3312 8774

$$

75

This storm fell apart in the last 15 minutes, and most of the other rain in the state is disappearing too. Looks like another overhyped non-event! We're never breaking this drought...

[tidesong]

Impressive coverage out of Evansville stream: http://14wfie.com/

[Bunkertor]

I´d say, time for PDS for KY

[CrazyC83]

I´d say, time for PDS for KY

To go PDS they'd need to kill the existing watches.

[CrazyC83]

Described by WFIE as the "best supercells in 20 years of tracking"...

[CrazyC83]

WFIE: Confirmed structural damage in Daviess County...

[Bunkertor]

I´d say, time for PDS for KY

To go PDS they'd need to kill the existing watches.

But why. Can you explain in short words ?

[CrazyC83]

MESOSCALE DISCUSSION 2116
NWS STORM PREDICTION CENTER NORMAN OK
0630 PM CDT THU OCT 18 2007

AREAS AFFECTED...WRN OH AND NCNTRL/CNTRL KY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 182330Z - 190100Z

LATEST SFC AND OBJECTIVE ANALYSES PORTRAY MORE SUBSTANTIAL LOW-LEVEL
THETA-E AXIS BEGINNING TO ADVECT NWD INTO NWRN KY AND SCNTRL IND
WHERE SFC DEW POINTS WERE IN THE MID-UPR 60S. MODEL GUIDANCE
SUGGESTS THIS AXIS WILL SHIFT NEWD INTO WRN OH AND NCNTRL KY WITH
TIME THIS EVENING. POSSIBLE TORNADIC SUPERCELL VCNTY KSDF HAS BEEN
WEAKENING AS IT APPROACHES THE ERN EDGE OF THIS INSTABILITY AXIS AND
NERN EDGE OF TORNADO WATCH 722. THROUGH THE EVENING...HOWEVER...AS
THE SLY LLJ BEGINS TO INTENSIFY IN RESPONSE TO THE UPR TROUGH
SWINGING NEWD INTO THE UPR MIDWEST/GRTLKS... COMBINATION OF LARGE
SCALE ASCENT AND DESTABILIZING COLUMN WILL SUPPORT TSTMS.

SHEAR PROFILES WILL CONTINUE TO IMPROVE...SUPPORTING SUPERCELL
STRUCTURES. BUT...AS THE DEEP LAYER FLOW BACKS ALONG THE SERN
PERIPHERY OF THE UPR CYCLONE...MORE OF A LINEAR EVOLUTION TO THE
STORMS SHOULD ENSUE LATER THIS EVENING. ATTM...GIVEN THE SLOW EWD
MOVEMENT OF THE UPSTREAM STORMS AND A FEW HOURS OF DESTABILIZATION
NEEDED TO SUPPORT STORMS...IT APPEARS THAT A WATCH MAY BE
NEEDED...BUT MORE LIKELY TOWARD MID-EVENING ACROSS PORTIONS OF WRN
OH AND NCNTRL/CNTRL KY.

..RACY.. 10/18/2007


ATTN...WFO...CLE...JKL...ILN...LMK...IWX...

39418498 40078459 41608432 41578314 40708293 39358312
37998371 37558471 37688487

[CrazyC83]

I´d say, time for PDS for KY

To go PDS they'd need to kill the existing watches.

But why. Can you explain in short words ?

In order to upgrade a watch for much or all of an area already under a watch, the original watch needs to be canceled.

[Bunkertor]

To go PDS they'd need to kill the existing watches.

But why. Can you explain in short words ?

In order to upgrade a watch for much or all of an area already under a watch, the original watch needs to be canceled.

But it´s only an upgrade, whay can´t the shift to pds ? You mean it´s to complicated to tell folks in 20 counties, they are under pds ?

[CrazyC83]

MESOSCALE DISCUSSION 2117
NWS STORM PREDICTION CENTER NORMAN OK
0634 PM CDT THU OCT 18 2007

AREAS AFFECTED...LOWER MI...ERN IL...IN...

CONCERNING...TORNADO WATCH 724...

VALID 182334Z - 190130Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 724 CONTINUES.

THREAT FOR TORNADOES AS WELL AS PARTICULARLY DAMAGING WIND GUSTS HAS
BECOME HIGH FROM SRN MI SWD.

SURFACE ANALYSIS SHOWS MAIN SURFACE DRYLINE/WIND SHIFT WELL TO THE
WEST OVER WRN IL AND MO...WITH NUMEROUS STORMS TO THE E IN THE WARM
SECTOR. SHEAR PROFILES ARE EXCEPTIONALLY STRONG...WITH 0-6KM SHEAR
OF 70-80KT AND 0-1 SHEAR IN EXCESS OF 30 KT. PRIMARY STORM MODE IS
THUS EXPECTED TO REMAIN SUPERCELLULAR WITH A THREAT OF
TORNADOES...POSSIBLY STRONG...AND VERY STRONG WIND GUSTS.

WHILE INSTABILITY IS NOT PARTICULARLY HIGH...SURFACE ANALYSIS DOES
SHOW DEWPOINTS RISING INTO THE MID 60S ALONG THE OH RIVER. A
PERSISTENT AND STRONG LOW LEVEL JET MAY BRING THE HIGHER LEVELS OF
MOISTURE NWD...POSSIBLY INCREASING THE TORNADO THREAT INTO IN AND
WRN OH LATER THIS EVENING.

..JEWELL.. 10/18/2007


ATTN...WFO...DTX...APX...LMK...IWX...GRR...IND...PAH...LOT...ILX...LSX...

45658128 38638614 38578962 45668518

[Coredesat]

No, if you have a watch in effect for a given area and you have to issue a more serious watch (like a PDS), the more serious watch wins.

A good example is severe thunderstorm watches and tornado watches. Severe thunderstorm watches and tornado watches are almost never issued at the same time for the same exact area. If a tornado watch is needed where there's a severe thunderstorm watch, the severe thunderstorm watch has to be cancelled.

[CrazyC83]

To go PDS they'd need to kill the existing watches.

But why. Can you explain in short words ?

In order to upgrade a watch for much or all of an area already under a watch, the original watch needs to be canceled.

But it´s only an upgrade, whay can´t the shift to pds ? You mean it´s to complicated to tell folks in 20 counties, they are under pds ?

It's all internal stuff at the SPC; they cannot reclassify existing watches. If such warrants, they could cancel the current watch and replace it with a new PDS watch...

[Bunkertor]

Ahhhhh, thanks. I got it. Then the warning outruns a pds...

[CrazyC83]

Watch 723 has ended.

[CrazyC83]

Brutal cell in Marshall County, KY...

[WindRunner]

That's for sure, though it's into Lyon County now. The one just south of it in northern Calloway isn't looking half-bad on BV either, and has a HUGE hail-core about to come flying down - i.e 72.5dbZ at 32kft!

There's also a nice cell just west of Louisville that's had a very nice hook for a good half-hour now, with GTG shear approaching 70kts.

[CrazyC83]

I can't remember there ever being an outbreak this widespread. This is covering more ground than the Super Outbreak!

[btangy]

Some very tight rotational couplets (particularly S of Henderson City and E of Paducah):

[WindRunner]

For those interested . . . first is the base reflectivity shot of our two southernmost cells, with the cell Crazy mentioned near the center and the cell with the huge hail core towards the bottom.



3-D view of the storm with the hail core. You can see the white blob (70+ dbZ) way up there. Note the yellow and red lines on the back "walls" of the view, they represent the 0C and -20C lines, respectively - which shows you just how far up that core goes.