Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 69

January 25, 201231 parishes in Louisiana; 16 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Jan 25, 2012, 11:24 AM CST for 31 parishes in Louisiana; 16 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jan 25, 2012, 11:24 AM CST (17:24 UTC)
Expired
Jan 25, 2012, 1:30 PM CST
In force
2 hr
Issued by
the Storm Prediction Center
All 47 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Union Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Brazoria County, TX, Chambers County, TX, Galveston County, TX, Hardin County, TX, Harrison County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Marion County, TX, Newton County, TX, Orange County, TX, Panola County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Tyler County, TX

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 5.4 hours before the alert went out and 87 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lake Charles Mun, LA at 12:00Z on 2012-01-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 28 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lake Charles Mun, LA at 12:00Z on 2012-01-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 241 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
28 J/kg
Mixed-layer CIN
-201 J/kg
Mixed-layer LCL
576 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
241 m²/s²
0-3 km storm-relative helicity
341 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.6

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

949 
ACUS11 KWNS 251725
SWOMCD
SPC MCD 251724
LAZ000-ARZ000-TXZ000-251930-

MESOSCALE DISCUSSION 0069
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CST WED JAN 25 2012

AREAS AFFECTED...SERN TX...LA

CONCERNING...TORNADO WATCH 15...

VALID 251724Z - 251930Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 15 CONTINUES.

A LINE OF STORMS WITH OCCASIONAL EMBEDDED MESOCYCLONES CONTINUES
ACROSS ERN TX. THE NRN END OF THIS LINE IS MOVING NEWD AT A
RELATIVELY FAST PACE...AND WILL ENTER NWRN LA SHORTLY WITH PERHAPS A
DAMAGING WIND THREAT. THIS AREA IS CURRENTLY N OF THE WARM
FRONT...THEREFORE LOW LEVEL BUOYANCY WILL BE LESS THAN POINTS S.

A BETTER JUXTAPOSITION OF LOW LEVEL SHEAR...INSTABILITY AND MOISTURE
EXISTS OVER ERN TX...AND EVENTUALLY INTO SWRN LA. DAMAGING WINDS AND
ISOLATED TORNADOES WILL CONTINUE TO BE POSSIBLE OVER THE NEXT
SEVERAL HOURS AS THE PRIMARY LINE OF CONVECTION NEARS. THOUGH STORM
MODE IS NOT OPTIMAL FOR TORNADOES WITH MERIDIONAL ORIENTED DEEP
LAYER SHEAR...0-1 SRH VALUES ARE OVER 300-400 M2/S2...WHICH MAY HELP
TO COMPENSATE.

..JEWELL.. 01/25/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAN...LIX...LCH...SHV...HGX...

LAT...LON   29889191 29439229 29639356 29129477 28689560 29269581
            29819525 30459477 31519424 31919429 32979452 33059373
            33079231 32819190 31219170 29889191

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 25, 7:56 AM CSTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 24 more7 hr
Jan 25, 1:41 PM CSTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 13 more94 min
Jan 25, 2:08 PM CSTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 41 more7 hr
Jan 25, 4:49 PM CSTMesoscale DiscussionSPCAcadia, Allen, Ascension, Avoyelles, Cameron, Catahoula and 24 more86 min
Jan 24, 7:13 PM CSTMesoscale DiscussionSPCAtascosa, Bandera, Bastrop, Bexar, Blanco, Caldwell and 23 more92 min
Jan 24, 10:05 PM CSTTornado WatchSPCAtascosa, Bandera, Bastrop, Bee, Bexar, Blanco and 33 more5 hr
Jan 24, 11:34 PM CSTMesoscale DiscussionSPCAtascosa, Bandera, Bastrop, Bee, Bexar, Blanco and 38 more56 min
Jan 25, 2:12 AM CSTMesoscale DiscussionSPCAtascosa, Austin, Bandera, Bastrop, Bee, Bell and 56 more2 hr
Jan 25, 3:17 AM CSTTornado WatchSPCAnderson, Aransas, Atascosa, Austin, Bastrop, Bee and 67 more11 hr
Jan 25, 7:13 AM CSTMesoscale DiscussionSPCAnderson, Angelina, Aransas, Austin, Bee, Brazoria and 40 more2 hr
Jan 25, 10:09 AM CSTMesoscale DiscussionSPCBrazoria, Chambers, Fort Bend, Harris, Liberty, Matagorda and 5 more96 min

Nearby

Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.