Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 2072

October 17, 201212 parishes in Louisiana; 37 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Oct 17, 2012, 11:49 PM CDT for 12 parishes in Louisiana; 37 counties in Mississippi. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Oct 17, 2012, 11:49 PM CDT (04:49 UTC)
Expired: Oct 18, 2012, 1:15 AM CDT
In force: 86 min
Issued by: the Storm Prediction Center

All 49 counties

Caldwell Parish, LA, Catahoula Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Natchitoches Parish, LA, Richland Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Clay County, MS, Copiah County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Itawamba County, MS, Jefferson County, MS, Lawrence County, MS, Leake County, MS, Lee County, MS, Leflore County, MS, Lincoln County, MS, Madison County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Oktibbeha County, MS, Pontotoc County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Warren County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 48 km from the middle of the area, began a volume at 04:50 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 nearest sounding before it

Jackson, MS (KJAN), launched 00:00Z, 4.8 hours before the alert went out and 41 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: 229 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 1020 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: 157 m²/s²
0-3 km storm-relative helicity: 316 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

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

550 
ACUS11 KWNS 180450
SWOMCD
SPC MCD 180449
MSZ000-LAZ000-ARZ000-180615-

MESOSCALE DISCUSSION 2072
NWS STORM PREDICTION CENTER NORMAN OK
1149 PM CDT WED OCT 17 2012

AREAS AFFECTED...PARTS OF MS AND INTO ADJACENT NRN LA

CONCERNING...TORNADO WATCH 667...668...670...

VALID 180449Z - 180615Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH
667...668...670...CONTINUES.

SUMMARY...THOUGH TORNADO THREAT IS SLOWLY DECREASING...ISOLATED
POTENTIAL CONTINUES...

DISCUSSION...LATEST RADAR LOOP SHOWS AN OVERALL DECREASE IN
CONVECTIVE ORGANIZATION AND INTENSITY OVER THE PAST COUPLE OF
HOURS...PARTICULARLY FROM NRN MS NWD WHERE STORMS HAVE EXITED THE
MORE FAVORABLE ZONE OF LOW-LEVEL MOISTURE/INSTABILITY.

STILL...WITH AN AMPLY MOIST/UNSTABLE PRE-FRONTAL BOUNDARY LAYER
EVIDENT FROM CENTRAL MS SWWD...ISOLATED TORNADO POTENTIAL CONTINUES
WITH A FEW STRONGER/ISOLATED CELLS.  ONCE SUCH CELL -- NOW CROSSING
INTO MADISON COUNTY MS -- HAS MAINTAINED LOW-LEVEL ROTATION...AND
APPEARS TO BE THE MOST SUBSTANTIAL THREAT ATTM.  EXPECT LIMITED
TORNADO/SEVERE THREAT TO CONTINUE FOR THE NEXT COUPLE OF HOURS.

..GOSS.. 10/18/2012

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

ATTN...WFO...MEG...JAN...SHV...

LAT...LON   31499003 31549338 33269089 33949019 34478818 32488884
            31499003

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 17, 7:01 PM CDT	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Catahoula, Claiborne and 20 more	8 hr
Oct 17, 9:28 PM CDT	Mesoscale Discussion	SPC	Bienville, Caldwell, Catahoula, Claiborne, Concordia, De Soto and 18 more	92 min
Oct 18, 1:16 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Calcasieu, East Baton Rouge and 12 more	59 min
Oct 18, 2:40 AM CDT	Mesoscale Discussion	SPC	Ascension, East Baton Rouge, East Feliciana, Iberville, Livingston, Pointe Coupee and 8 more	65 min
Oct 17, 7:35 PM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, DeSoto, Panola, Quitman, Tallahatchie and 2 more	85 min
Oct 17, 8:07 PM CDT	Mesoscale Discussion	SPC	Alcorn	53 min
Oct 17, 8:23 PM CDT	Tornado Watch	SPC	Alcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 8 more	5 hr
Oct 18, 1:09 AM CDT	Mesoscale Discussion	SPC	George, Greene, Perry, Stone	96 min

Nearby

Mesoscale Discussions in Mississippi, 2012 Mesoscale Discussions in Louisiana, 2012 Every mesoscale discussion in 2012

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.