Alert archive / Mississippi / Mesoscale Discussions in 2003

Mesoscale Discussion 2202

August 20, 2003Saint Tammany Parish, Washington Parish, Louisiana; 12 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2003, 5:12 PM CDT for Saint Tammany Parish, Washington Parish, Louisiana; 12 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 20, 2003, 5:12 PM CDT (22:12 UTC)
Expired: Aug 20, 2003, 7:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Saint Tammany Parish, LA, Washington Parish, LA, Forrest County, MS, George County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson Davis County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Walthall County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 10.2 hours before the alert went out and 70 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: 2728 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 662 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: 15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

776 
ACUS11 KWNS 202212
SWOMCD
SPC MCD 202212 
ALZ000-MSZ000-LAZ000-210015-

MESOSCALE DISCUSSION 2202
NWS STORM PREDICTION CENTER NORMAN OK
0512 PM CDT WED AUG 20 2003

AREAS AFFECTED...SRN MS AND SERN LA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 202212Z - 210015Z

ISOLATED DAMAGING WINDS POSSIBLE WITH CONVECTIVE LINE THAT IS
EXPECTED TO ACCELERATE SWWD ACROSS SRN MS/SERN LA DURING THE NEXT
1-2 HOURS.  

STRONG CONVECTIVE LINE EXTENDING FROM 15 SW LUL TO 20 W MOB TO 30 SE
MOB AT 22Z HAS BECOME BETTER ORGANIZED DURING THE PAST HOUR WITH VIL
CORES OCCASIONALLY EXCEEDING 65 KG/M2. DESPITE WEAK DEEP
TROPOSPHERIC SHEAR ENVIRONMENT...STRONG MESOSCALE COLD POOL
ASSOCIATED WITH CONVECTIVE DOWNDRAFTS/RAIN COOLED AIR IN THE WAKE OF
THE CONVECTION ACROSS SWRN AL RESULTED IN A SWD ACCELERATION OF
STORMS ACROSS MOBILE BAY BETWEEN 2130-2200Z. GIVEN INTENSE STORMS ON
NWRN FLANK OF CONVECTIVE LINE...A SIMILAR EVOLUTION APPEARS LIKELY
ACROSS SRN MS/SERN LA AS A MESOSCALE COLD POOL BECOMES ORGANIZED IN
VICINITY OF PERRY/STONE/FORREST COUNTIES IN SRN MS DURING THE NEXT
HOUR. A SWWD ACCELERATION OF STORMS ACROSS THE DISCUSSION AREA MAY
SUPPORT LOCALIZED DAMAGING WIND GUSTS WITH ANY BOWING SEGMENTS
WITHIN THE LINE. MLCAPE VALUES OF 2000-2500 J/KG AND MINIMAL CIN
SHOULD SUPPORT CONTINUED REDEVELOPMENT OF STORMS ALONG LEADING
OUTFLOW BOUNDARY AS IT SURGES SWWD INTO NERN LA BY 00Z. HIGH WBZ
HEIGHTS SHOULD MITIGATE POTENTIAL FOR LARGE HAIL.

..BANACOS.. 08/20/2003

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

ATTN...WFO...MOB...JAN...LIX...

31608951 31258906 30908861 30608835 30458837 30398852
30348884 30188925 30158958 30268991 30479019 30949040
31369033 31598998

Nearby

Mesoscale Discussions in Mississippi, 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.