Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 213

March 2, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Mar 2, 2012, 1:26 PM CST for 4 states. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: Mar 2, 2012, 1:26 PM CST (19:26 UTC)
Expired: Mar 2, 2012, 2:30 PM CST
In force: 64 min
Issued by: the Storm Prediction Center

All 33 counties

Ashley County, AR, Chicot County, AR, Bienville Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Humphreys County, MS, Issaquena County, MS, Sharkey County, MS, Warren County, MS, Washington County, MS, Yazoo County, MS, Nacogdoches County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX

The radar

The Shreveport radar (KSHV), 146 km from the middle of the area, began a volume at 19:27 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

Shreveport, LA (KSHV), launched 12:00Z, 7.4 hours before the alert went out and 137 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: 1427 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 626 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 347 m²/s²
0-3 km storm-relative helicity: 292 m²/s²
Significant tornado parameter: 2.5
Supercell composite: 9.6

Open this sounding in Storm Lab

The text

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

993 
ACUS11 KWNS 021927
SWOMCD
SPC MCD 021926
MSZ000-ARZ000-LAZ000-TXZ000-022030-

MESOSCALE DISCUSSION 0213
NWS STORM PREDICTION CENTER NORMAN OK
0126 PM CST FRI MAR 02 2012

AREAS AFFECTED...W-CNTRL MS...NRN LA...E TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 021926Z - 022030Z

RADAR TRENDS SHOW INCREASING COVERAGE OF TSTMS ALONG AN EWD
PROGRESSING DRYLINE ACROSS NRN LA. PRIMARY THREATS APPEAR TO BE
LARGE HAIL AND DMGG WINDS...BUT AN ISOLATED TORNADO CANNOT BE RULED
OUT. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

19Z SFC ANALYSIS SHOWS AN APPARENT DRYLINE /POSITIONED FROM 30 E ELD
TO 35 SSE GGG/ MOVING EWD ACROSS NRN LA/ E TX...WHILE PRIMARY
SYNOPTIC-SCALE COLD FRONT REMAINS POSITIONED FARTHER TO THE NW.
RADAR IMAGERY INDICATES AN INCREASE IN TSTMS IS OCCURRING ALONG THE
DRYLINE OVER N-CNTRL LA. STRONG DIABATIC HEATING OVER THIS
REGION...WITH TEMPERATURES REACHING THE LOWER 80S...HAS YIELDED
MLCAPE VALUES NEAR 1000 J/KG /PER RUC OBJECTIVE ANALYSIS/. STRONG
DEEP-LAYER WIND FIELDS /30-40 KTS AT 2 KM AGL PER POE AND DGX VWP
DATA/ ALONG WITH STEEP LOW-LEVEL LAPSE RATES WILL LEAD TO AN
ENHANCED THREAT FOR DMGG WIND GUSTS. TOR THREAT DOES NOT APPEAR TO
BE AS ROBUST AS AREAS FARTHER N/E...AS LOW-LEVEL FLOW HAS A
SIGNIFICANT WLY COMPONENT...AND CONVECTIVE MODE WILL LIKELY FAVOR
BROKEN LINES ANCHORED NEAR/AHEAD OF THE DRYLINE. HOWEVER...AN
ISOLATED TORNADO THREAT STILL CANNOT BE RULED OUT GIVEN STRONG FLOW
FIELDS.

..ROGERS.. 03/02/2012

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

ATTN...WFO...JAN...LZK...LCH...SHV...

LAT...LON   32789029 32139095 31519237 31169422 31389493 31779476
            32819315 33259223 33549140 33519059 32789029

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 2, 10:28 AM CST	Mesoscale Discussion	SPC	Clay, Craighead, Crittenden, Cross, Greene, Independence and 10 more	62 min
Mar 2, 1:47 PM CST	Severe Thunderstorm Watch	SPC	Ashley, Chicot	9 hr
Mar 2, 3:47 PM CST	Mesoscale Discussion	SPC	Ashley, Chicot	58 min
Mar 2, 2:42 PM CST	Mesoscale Discussion	SPC	Ascension, East Baton Rouge, East Feliciana, Livingston, Saint Helena, Saint Tammany and 2 more	63 min
Mar 2, 12:57 PM CST	Mesoscale Discussion	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 32 more	63 min
Mar 2, 1:20 PM CST	Tornado Watch	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 24 more	9 hr
Mar 2, 3:25 PM CST	Mesoscale Discussion	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 24 more	65 min
Mar 2, 4:37 PM CST	Tornado Watch	SPC	George, Greene, Perry, Stone, Wayne	7 hr
Mar 2, 4:47 PM CST	Tornado Watch	SPC	Attala, Choctaw, Clarke, Clay, Copiah, Covington and 23 more	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Mississippi, 2012 Mesoscale Discussions in Texas, 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.