Alert archive / Louisiana / Mesoscale Discussions in 2004

Mesoscale Discussion 2339

October 19, 200445 parishes in Louisiana; 9 counties in Mississippi; Newton County, Sabine County, Texas

The Storm Prediction Center issued this mesoscale discussion at Oct 19, 2004, 1:35 PM CDT for 45 parishes in Louisiana; 9 counties in Mississippi; Newton County, Sabine County, Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Oct 19, 2004, 1:35 PM CDT (18:35 UTC)
Expired: Oct 19, 2004, 4:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 56 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Iberville Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Madison Parish, LA, Natchitoches Parish, LA, Orleans Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Sabine Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Franklin County, MS, Hancock County, MS, Issaquena County, MS, Jefferson County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS, Newton County, TX, Sabine County, TX

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 6.6 hours before the alert went out and 170 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2756 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 631 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 168 m²/s²
0-3 km storm-relative helicity: 186 m²/s²
Significant tornado parameter: 2.4
Supercell composite: 11.4

Open this sounding in Storm Lab

The text

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

277 
ACUS11 KWNS 191835
SWOMCD
SPC MCD 191835 
LAZ000-MSZ000-TXZ000-192100-

MESOSCALE DISCUSSION 2339
NWS STORM PREDICTION CENTER NORMAN OK
0135 PM CDT TUE OCT 19 2004

AREAS AFFECTED...PORTIONS EXTREME E TX...CENTRAL/SRN LA...SWRN MS
AWAY FROM WW 866

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 191835Z - 192100Z

CONDITIONAL SEVERE THREAT FROM SABINE RIVER AREA EWD ACROSS LA
TOWARD MS RIVER...W AND SW OF WW 866.  PRIND MOST OF THIS AREA WILL
REMAIN TOO CAPPED AND WEAKLY CONVERGENT FOR TSTMS...EXCEPT OVER
COASTAL S-CENTRAL/SERN LA.  SHEAR PROFILES OVER EXTREME E TX AND
CENTRAL LA FAVOR SUPERCELLS WHERE STORMS CAN FORM.  MANY OFFSETTING
FACTORS EVIDENT ATTM...INDICATING TSTMS MAY BE ISOLATED AT BEST. 
THEREFORE WILL CONTINUE TO MONITOR IN EVENT CAP BEGINS TO BREAK
WHERE SHEAR IS STRONGEST.

MODIFIED RAOBS AND RUC SOUNDINGS INDICATE BOUNDARY LAYER
DESTABILIZING...THOUGH MIDLEVEL TEMPS ARE WARMING.  THIS RESULTS IN
MLCAPES APCHG 3000 J/KG FOR MID 70S F SFC DEW POINTS.  CINH APPEARS
TO BE WEAKER THAN 50 J/KG ACROSS MUCH OF REGION ATTM...HOWEVER
CONVERGENCE SHOULD REMAIN WEAK AS WELL.  HORIZONTAL CONVECTIVE ROLLS
EVIDENT IN VIS IMAGERY ACROSS THIS REGION -- WITH OCCASIONAL DEEP CU
AND TCU EMBEDDED...ARE ALIGNED SW-NE WITH BOUNDARY LAYER SHEAR
VECTOR.  SFC ANALYSIS SHOWS VEERED/SWLY FLOW ACROSS REGION...WHICH
WILL CONTINUE TO LIMIT MESOSCALE CONVERGENCE...MAKING MORE LOCALIZED
HCR ENHANCEMENTS THE MAIN SOURCE OF LIFT.  DEEPER TOWERS EVIDENT
IBERIA/VERMILION/IBERVILLE PARISHES MAY DEVELOP INTO TSTMS NEXT 1-2
HOURS...WITH LINEAR MODE LIKELY GIVEN UNIDIRECTIONAL PROFILES AND
WEAKER SHEAR OVER SERN LA.

..EDWARDS.. 10/19/2004

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

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

31208998 30328931 29609025 29539136 29869241 30099372
30619404 31389391 31819374 32369290 32749197 32799096
31769102

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 18, 7:10 PM CDT	Tornado Watch	SPC	Alcorn, Benton, Calhoun, Chickasaw, Choctaw, Clay and 15 more	4 hr
Oct 18, 9:09 PM CDT	Mesoscale Discussion	SPC	Alcorn, Benton	2 hr
Oct 18, 10:33 PM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, Bolivar, Calhoun, Coahoma, DeSoto and 16 more	117 min
Oct 18, 10:55 PM CDT	Tornado Watch	SPC	Alcorn, Benton, Coahoma, DeSoto, Itawamba, Lafayette and 11 more	5 hr
Oct 19, 2:04 AM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, Coahoma, Itawamba, Lafayette, Lee and 9 more	86 min
Oct 19, 3:34 AM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, Coahoma, DeSoto, Itawamba, Lafayette and 11 more	26 min
Oct 19, 3:50 AM CDT	Severe Thunderstorm Watch	SPC	Alcorn, Chickasaw, Itawamba, Lee, Monroe, Prentiss and 2 more	4 hr
Oct 19, 7:08 AM CDT	Mesoscale Discussion	SPC	Chickasaw, Itawamba, Lee, Monroe	2 hr
Oct 19, 9:05 AM CDT	Tornado Watch	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 21 more	7 hr
Oct 19, 11:06 AM CDT	Mesoscale Discussion	SPC	Clarke, Copiah, Covington, Forrest, Franklin, Greene and 16 more	84 min
Oct 19, 12:00 PM CDT	Tornado Watch	SPC	Claiborne, Clarke, Copiah, Covington, Forrest, Franklin and 21 more	7 hr
Oct 19, 1:15 PM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 20 more	90 min
Oct 19, 3:08 PM CDT	Mesoscale Discussion	SPC	Amite, Attala, Calhoun, Carroll, Chickasaw, Choctaw and 51 more	67 min
Oct 19, 3:30 PM CDT	Tornado Watch	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 21 more	6 hr
Oct 19, 5:48 PM CDT	Mesoscale Discussion	SPC	Clarke, Covington, Hinds, Jasper, Jones, Kemper and 10 more	117 min
Oct 19, 6:20 PM CDT	Tornado Watch	SPC	Clarke, Covington, Forrest, Greene, Jasper, Jones and 9 more	4 hr

Nearby

Mesoscale Discussions in Louisiana, 2004 Mesoscale Discussions in Mississippi, 2004 Mesoscale Discussions in Texas, 2004 Every mesoscale discussion in 2004

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.