Alert archive / Louisiana / Mesoscale Discussions in 2003

Mesoscale Discussion 438

April 7, 200326 parishes in Louisiana; 5 counties in Mississippi; 4 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 7, 2003, 2:36 PM CDT for 26 parishes in Louisiana; 5 counties in Mississippi; 4 counties in Texas. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Apr 7, 2003, 2:36 PM CDT (19:36 UTC)
Expired
Apr 7, 2003, 4:30 PM CDT
In force
114 min
Issued by
the Storm Prediction Center
All 35 counties

Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee 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, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, Hancock County, MS, Harrison County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Chambers County, TX, Hardin County, TX, Jefferson County, TX, Orange County, TX

The radar

The Lake Charles radar (KLCH), 81 km from the middle of the area, began a volume at 19:37 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

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, 7.6 hours before the alert went out and 79 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 2003-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1791 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 2003-04-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -64 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
1791 J/kg
Mixed-layer CIN
-58 J/kg
Mixed-layer LCL
518 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
-64 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
-0.6
Supercell composite
-2.0

Open this sounding in Storm Lab

The text

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

861 
ACUS11 KWNS 071937
SWOMCD
SPC MCD 071936 
MSZ000-LAZ000-TXZ000-072130-

MESOSCALE DISCUSSION 0438
NWS STORM PREDICTION CENTER NORMAN OK
0236 PM CDT MON APR 07 2003

AREAS AFFECTED...S-CENTRAL/SERN TX...SRN LA...SRN MS

CONCERNING...SEVERE THUNDERSTORM WATCH 112...113...

VALID 071936Z - 072130Z

BAND OF SIGNIFICANT SEVERE HAILSTORMS -- PRIMARILY IN FORM OF
HEAVY-PRECIP SUPERCELLS -- WILL CONTINUE AT LEAST ANOTHER 2 HOURS
FROM HOU AREA ENEWD ACROSS LAKE PONTCHARTRAIN AREA...
EXPANDING/MOVING EWD ACROSS CLOSEST 2 TIERS OF MS COUNTIES
CLOSEST TO COAST.  DESPITE STRONGER CAPPING FARTHER W -- EVIDENT
IN MODIFIED CRP/DRT RAOBS AND RUC FORECAST SOUNDINGS...CONTINUED
LIFT ALONG SFC CONFLUENCE/TROUGH LINE AND DIABATIC HEATING SHOULD
AID IN ADDITIONAL DEVELOPMENT ACROSS S TX.  CONVECTIVE BAND MAY
BACKBUILD WWD ACROSS WW 113...WITH DISCRETE/RELATIVELY ISOLATED
SUPERCELLS EVOLVING INTO BROKEN LINE OF SEVERE CONVECTION.  



HAIL EXCEEDING 4 INCHES HAS BEEN REPORTED IN PORTIONS
IBERIA/VERMILION PARISHES OVER PAST COUPLE HOURS.  ENVIRONMENTAL
SHEAR PROFILES AND THERMODYNAMICS WILL CONTINUE TO FAVOR
LARGE/DAMAGING HAIL -- AS WELL AS FORMATION OF BOWS WITH DAMAGING
WIND -- OVER WW.  WEAKNESSES IN LOW LEVEL SR FLOW AGL INDICATE
CONTINUED DEVELOPMENT OF STORM-SCALE PRECIP DISTRIBUTIONS LEADING
TO HP UPDRAFT CHARACTER...HOWEVER 40-50 KT 0-6 KM AGL SHEARS WILL
BE MAINTAINED...SUPPORTING SUSTAINED/ORGANIZED STORM ROTATION. 
INFLOW-LAYER MLCAPE RANGES FROM AROUND 1500-2500 J/KG ACROSS WWS
WITH 8-9 DEG C/KM MIDLEVEL LAPSE RATES BEING COMMON.  



REF SPC MESOSCALE DISCUSSION 437 FOR NOWCAST DETAILS ON HEAVY
RAIN HAZARD WITHIN SUBSET OF THESE WWS.

..EDWARDS.. 04/07/2003

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

ATTN...WFO...MOB...JAN...LIX...LCH...HGX...

29439485 30329457 31218882 30198903 29359222

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 6, 8:13 PM CDTMesoscale DiscussionSPCCatahoula, Concordia, Franklin, LaSalle, Tensas2 hr
Apr 7, 9:42 AM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 16 more3 hr
Apr 7, 10:05 AM CDTSevere Thunderstorm WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 26 more6 hr
Apr 7, 11:02 AM CDTMesoscale DiscussionSPCAcadia, Ascension, Cameron, East Baton Rouge, Iberville, Lafayette and 8 more3 hr
Apr 7, 2:13 PM CDTMesoscale DiscussionSPCAcadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 20 more3 hr
Apr 7, 3:40 PM CDTSevere Thunderstorm WatchSPCAcadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 22 more5 hr
Apr 7, 5:58 PM CDTMesoscale DiscussionSPCAscension, Assumption, Cameron, Iberia, Iberville, Lafayette and 10 more2 hr
Apr 6, 9:48 PM CDTMesoscale DiscussionSPCClarke, Covington, Jasper, Jefferson Davis, Jones, Kemper and 5 more87 min
Apr 7, 4:49 AM CDTMesoscale DiscussionSPCKemper, Lauderdale, Newton3 hr
Apr 7, 9:11 AM CDTMesoscale DiscussionSPCForrest, George, Greene, Jones, Lamar, Pearl River and 2 more3 hr
Apr 7, 11:25 AM CDTMesoscale DiscussionSPCGeorge, Greene3 hr
Apr 7, 12:07 PM CDTMesoscale DiscussionSPCGeorge, Greene113 min
Apr 7, 12:22 PM CDTMesoscale DiscussionSPCGeorge, Greene113 min
Apr 7, 12:24 PM CDTMesoscale DiscussionSPCAtascosa, Austin, Bastrop, Bee, Bexar, Brazoria and 28 more66 min
Apr 7, 1:00 PM CDTSevere Thunderstorm WatchSPCAtascosa, Austin, Bee, Bexar, Brazoria, Caldwell and 23 more5 hr
Apr 7, 3:36 PM CDTMesoscale DiscussionSPCEdwards, Kinney, Maverick, Real, Uvalde, Val Verde114 min
Apr 7, 4:35 PM CDTSevere Thunderstorm WatchSPCAtascosa, Bandera, Bee, Bexar, Blanco, Caldwell and 22 more5 hr

Nearby

Mesoscale Discussions in Louisiana, 2003Mesoscale Discussions in Mississippi, 2003Mesoscale Discussions in Texas, 2003Every mesoscale discussion in 2003

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; radar from the NEXRAD Level II archive.