Alert archive / Texas / Mesoscale Discussions in 2003

Mesoscale Discussion 2621

December 22, 200314 counties in Arkansas; 7 parishes in Louisiana; 19 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 22, 2003, 7:29 PM CST for 14 counties in Arkansas; 7 parishes in Louisiana; 19 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Dec 22, 2003, 7:29 PM CST (01:29 UTC)
Expired: Dec 22, 2003, 9:30 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center

All 40 counties

Calhoun County, AR, Clark County, AR, Columbia County, AR, Dallas County, AR, Garland County, AR, Grant County, AR, Hot Spring County, AR, Lafayette County, AR, Nevada County, AR, Ouachita County, AR, Perry County, AR, Saline County, AR, Union County, AR, Yell County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Red River Parish, LA, Webster Parish, LA, Anderson County, TX, Cherokee County, TX, Freestone County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Houston County, TX, Leon County, TX, Limestone County, TX, Madison County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 84 km from the middle of the area, began a volume at 01:31 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.

Severe Thunderstorm Watch 983Dec 22, 8:00 PM CST

The nearest sounding before it

Shreveport, LA (KSHV), launched 00:00Z, 1.5 hours before the alert went out and 92 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: 232 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 982 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 205 m²/s²
0-3 km storm-relative helicity: 285 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 6.6

Open this sounding in Storm Lab

The text

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

184 
ACUS11 KWNS 230130
SWOMCD
SPC MCD 230129 
ARZ000-LAZ000-TXZ000-230330-

MESOSCALE DISCUSSION 2621
NWS STORM PREDICTION CENTER NORMAN OK
0729 PM CST MON DEC 22 2003

AREAS AFFECTED...PORTIONS E-CENTRAL/NE TX...NWRN LA...SWRN AR

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 230129Z - 230330Z

WIDELY SCATTERED TSTMS MAY DEVELOP S OF WW 982 ACROSS E TX THROUGH
APPROXIMATELY 4Z.  POTENTIAL EXISTS FOR BROKEN LINE OF TSTMS WITH
STRONG-SEVERE GUSTS AND HAIL BY 6Z FROM SW AR SSWWD ACROSS SE TX.
TSTMS MAY ALSO MOVE EWD OUT OF SRN PORTION WW 982.  50-80 NM WIDE
SEGMENT OF MOIST SECTOR E OF WW...OVER SW AR...WILL CONTAIN MUCAPE
300-700 J/KG AND INCREASING LOW-MIDLEVEL SHEAR THROUGH AT LEAST 4Z. 
ADDITIONAL OR REPLACEMENT WW MAY BE REQUIRED BY 3Z EXPIRATION TIME
OF ONGOING WW.

REF MESOSCALE DISCUSSION 2620 FOR SFC MESOANALYTIC DETAILS. 
STRONGEST LARGE SCALE FORCING AND KINEMATIC FIELDS ARE FCST TO
REMAIN N OF I-20.  HOWEVER...MIDLEVEL WIND FIELDS SHOULD STRENGTHEN
BETWEEN I-45 AND TX/LA BORDER REGION ENOUGH TO SUPPORT SEVERE
THREAT...AS COMBINED FRONT/DRYLINE/CONFLUENCE BOUNDARY SWEEPS EWD
INTO AIR MASS CHARACTERIZED BY UPPER 50S TO MID 60S F SFC DEW
POINTS.  50-60 KT 0-6 KM AGL SHEARS SHOULD EXTEND AS FAR S AS LFK
AREA AFTER 3Z WITH 250-350 J/KG SRH POSSIBLE IN 0-3 KM LAYER.  THIS
WILL SUPPORT ROTATION IN DISCRETE CELLS...ENHANCING HAIL POTENTIAL. 
500-800 J/KG MUCAPE POSSIBLE OVER SAME AREA...ROOTED NEAR 900 MB
LEVEL. TSTMS SHOULD BACKBUILD ALONG OR JUST AHEAD OF COLD
FRONT...WITH MODE EVOLVING TO LINEAR THROUGH REMAINDER EVENING.

..EDWARDS.. 12/23/2003

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

ATTN...WFO...LZK...SHV...HGX...FWD...

31749671 32909576 32889372 35599334 34719226 33039236
31479385 30909590 31289656

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 22, 6:32 PM CST	Mesoscale Discussion	SPC	Benton, Carroll, Crawford, Franklin, Hempstead, Howard and 12 more	118 min
Dec 22, 8:00 PM CST	Severe Thunderstorm Watch	SPC	Clark, Columbia, Dallas, Hempstead, Howard, Lafayette and 6 more	5 hr
Dec 22, 9:53 PM CST	Mesoscale Discussion	SPC	Clark, Columbia, Dallas, Hempstead, Howard, Lafayette and 6 more	97 min
Dec 22, 11:40 PM CST	Mesoscale Discussion	SPC	Columbia, Dallas, Lafayette, Nevada, Ouachita	95 min

Nearby

Mesoscale Discussions in Texas, 2003 Mesoscale Discussions in Arkansas, 2003 Mesoscale Discussions in Louisiana, 2003 Every 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.