Alert archive / Texas / Mesoscale Discussions in 2004

Mesoscale Discussion 539

May 1, 200430 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 1, 2004, 6:08 AM CDT for 30 counties in Texas. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
May 1, 2004, 6:08 AM CDT (11:08 UTC)
Expired
May 1, 2004, 7:45 AM CDT
In force
97 min
Issued by
the Storm Prediction Center
All 30 counties

Angelina County, TX, Austin County, TX, Brazos County, TX, Burleson County, TX, Chambers County, TX, Colorado County, TX, Fayette County, TX, Fort Bend County, TX, Grimes County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Lavaca County, TX, Lee County, TX, Liberty County, TX, Madison County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 90 km from the middle of the area, began a volume at 11:10 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 00:00Z, 11.1 hours before the alert went out and 259 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 00:00Z on 2004-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 493 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 00:00Z on 2004-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 155 square meters per square second.193958Sfc1 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
493 J/kg
Mixed-layer CIN
-85 J/kg
Mixed-layer LCL
688 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
260 m²/s²
Significant tornado parameter
0.4
Supercell composite
6.4

Open this sounding in Storm Lab

The text

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

034 
ACUS11 KWNS 011109
SWOMCD
SPC MCD 011108 
LAZ000-TXZ000-011245-

MESOSCALE DISCUSSION 0539
NWS STORM PREDICTION CENTER NORMAN OK
0608 AM CDT SAT MAY 01 2004

AREAS AFFECTED...SERN TX

CONCERNING...TORNADO WATCH 141...

VALID 011108Z - 011245Z

THREAT FOR ISOLATED TORNADOES CONTINUES.  

SURFACE ANALYSIS SHOWS OLD OUTFLOW BOUNDARY LOCATED NEAR
HOUSTON...WITH COOLER AND MORE STABLE SURFACE AIR TO THE EAST AND A
MORE UNSTABLE AIR MASS TO THE W.  MODIFIED RUC FORECAST SOUNDINGS
USING 73-74 F DEWPOINTS YIELD LITTLE IF ANY SURFACE BASED
INHIBITION. HGX VWP CONTINUES TO SHOW STRONG SHEAR IN THE LOWEST 1
KM.  USING CURRENT STORM MOTION OF 218/22 PRODUCES 0-1 KM SRH NEAR
300 M2/S2.  

GREATEST THREAT FOR TORNADOES WILL BE WITH SUPERCELLS THAT ARE ABLE
TO REMAIN ON WARM SIDE OF BOUNDARY BEFORE MOVING NEWD OVER A MORE
STABLE AIR MASS...BEFORE COLD FRONT MOVES INTO THE AREA FROM THE NW.
 LATEST VWPS ALSO INDICATE VEERING OF LOW LEVEL JET...WHICH WILL
DECREASE SHEAR OVER THE NEXT FEW HOURS.

..JEWELL.. 05/01/2004

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

ATTN...WFO...LCH...SHV...HGX...FWD...CRP...EWX...

28829731 30709731 31499372 29609373

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 30, 7:00 PM CDTMesoscale DiscussionSPCBosque, Brown, Coleman, Comanche, Concho, Eastland and 11 more90 min
Apr 30, 7:22 PM CDTMesoscale DiscussionSPCAnderson, Bowie, Camp, Cass, Cherokee, Delta and 25 more83 min
Apr 30, 7:40 PM CDTSevere Thunderstorm WatchSPCAnderson, Bowie, Camp, Delta, Ellis, Fannin and 20 more5 hr
Apr 30, 8:14 PM CDTMesoscale DiscussionSPCArcher, Clay, Collin, Cooke, Denton, Grayson and 8 more91 min
Apr 30, 9:07 PM CDTMesoscale DiscussionSPCBosque, Brown, Comanche, Coryell, Erath, Hamilton and 8 more53 min
Apr 30, 9:54 PM CDTMesoscale DiscussionSPCAnderson, Bowie, Camp, Delta, Ellis, Franklin and 19 more96 min
Apr 30, 10:34 PM CDTMesoscale DiscussionSPCBrown, Coleman, Concho, Crockett, Edwards, Irion and 15 more86 min
Apr 30, 11:35 PM CDTSevere Thunderstorm WatchSPCBlanco, Concho, Crockett, Edwards, Gillespie, Irion and 13 more5 hr
Apr 30, 11:56 PM CDTMesoscale DiscussionSPCChambers, Galveston, Grimes, Hardin, Harris, Jasper and 10 more94 min
May 1, 12:50 AM CDTSevere Thunderstorm WatchSPCAnderson, Bell, Bosque, Bowie, Camp, Cass and 47 more6 hr
May 1, 1:34 AM CDTMesoscale DiscussionSPCAtascosa, Bandera, Bexar, Blanco, Comal, Concho and 24 more86 min
May 1, 1:49 AM CDTMesoscale DiscussionSPCAnderson, Bell, Cherokee, Falls, Freestone, Henderson and 5 more86 min
May 1, 2:38 AM CDTMesoscale DiscussionSPCAngelina, Sabine, San Augustine, Shelby37 min
May 1, 3:10 AM CDTSevere Thunderstorm WatchSPCAngelina, Sabine, San Augustine, Shelby6 hr
May 1, 3:28 AM CDTMesoscale DiscussionSPCAtascosa, Bandera, Bexar, Blanco, Concho, Crockett and 23 more92 min
May 1, 3:41 AM CDTMesoscale DiscussionSPCAustin, Brazoria, Brazos, Burleson, Chambers, Colorado and 18 more64 min
May 1, 3:50 AM CDTTornado WatchSPCAngelina, Austin, Bastrop, Brazos, Burleson, Chambers and 25 more6 hr
May 1, 5:13 AM CDTMesoscale DiscussionSPCAnderson, Cherokee, Harrison, Nacogdoches, Panola, Rusk and 1 more92 min
May 1, 5:40 AM CDTSevere Thunderstorm WatchSPCAtascosa, Bee, Bexar, Caldwell, DeWitt, Dimmit and 17 more6 hr
May 1, 7:24 AM CDTMesoscale DiscussionSPCSabine, San Augustine, Shelby96 min
May 1, 7:33 AM CDTMesoscale DiscussionSPCAtascosa, Bee, Bexar, Caldwell, DeWitt, Dimmit and 16 more87 min
May 1, 7:47 AM CDTMesoscale DiscussionSPCAustin, Bastrop, Brazos, Burleson, Chambers, Colorado and 23 more88 min
May 1, 9:16 AM CDTMesoscale DiscussionSPCBrazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 3 more59 min
May 1, 9:36 AM CDTMesoscale DiscussionSPCNueces114 min
May 1, 9:45 AM CDTTornado WatchSPCBrazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 6 more5 hr
May 1, 9:55 AM CDTSevere Thunderstorm WatchSPCBrooks, Cameron, Hidalgo, Jim Hogg, Kenedy, Kleberg and 3 more5 hr
May 1, 11:15 AM CDTMesoscale DiscussionSPCKenedy2 hr
May 1, 1:14 PM CDTMesoscale DiscussionSPCWillacy2 hr

Nearby

Mesoscale Discussions in Texas, 2004Every 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; radar from the NEXRAD Level II archive.