Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 72

January 25, 201222 parishes in Louisiana; 8 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jan 25, 2012, 8:23 PM CST for 22 parishes in Louisiana; 8 counties in Mississippi. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Jan 25, 2012, 8:23 PM CST (02:23 UTC)
Expired: Jan 25, 2012, 10:00 PM CST
In force: 97 min
Issued by: the Storm Prediction Center

All 30 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Jefferson Davis County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pike County, MS, Simpson County, MS, Walthall County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.4 hours before the alert went out and 160 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: 794 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 544 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 225 m²/s²
0-3 km storm-relative helicity: 235 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 4.1

Open this sounding in Storm Lab

The text

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

919 
ACUS11 KWNS 260224
SWOMCD
SPC MCD 260223
MSZ000-LAZ000-260400-

MESOSCALE DISCUSSION 0072
NWS STORM PREDICTION CENTER NORMAN OK
0823 PM CST WED JAN 25 2012

AREAS AFFECTED...SOUTHERN/EASTERN LA INTO CENTRAL/SOUTHERN MS

CONCERNING...TORNADO WATCH 16...

VALID 260223Z - 260400Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 16 CONTINUES.

TORNADO WATCH 16 CONTINUES UNTIL 03Z. WHILE A SEVERE THREAT WILL
CONTINUE THIS EVENING...TORNADO/WIND DAMAGE POTENTIAL IS EXPECTED TO
BECOME MORE ISOLATED/MARGINAL THE REMAINDER OF THE NIGHT. LOCALLY
HEAVY RAINFALL WILL ALSO REMAIN POSSIBLE.

WELL-ORGANIZED SQUALL LINE /WITH EMBEDDED BOWING SEGMENTS/ CONTINUES
TO STEADILY PROGRESS EASTWARD ACROSS SOUTHERN LA AT MID-EVENING.
FARTHER NORTHEAST...THE INTEGRITY OF THE CONVECTIVE LINE HAS WANED
ACROSS NORTHEAST LA INTO CENTRAL MS AS OUTFLOW HAS SURGED
EASTWARD...ALTHOUGH THIS OUTFLOW MAY CONTINUE TO FOCUS SOME
ADDITIONAL DEVELOPMENT VIA THE ADJACENT WARM SECTOR. THAT SAID...A
SLIGHTLY COOLING BOUNDARY LAYER...TRENDS OF WARMING CLOUD TOPS PER
IR SATELLITE...AND A TENDENCY FOR SLIGHTLY WEAKENING LOW LEVEL FLOW
IMPLY A MORE ISOLATED/MARGINAL WIND DAMAGE/TORNADO THREAT THE
REMAINDER OF THE NIGHT. ALBEIT ON A MORE ISOLATED BASIS...THE
PRIMARY SEVERE THREAT WILL LIKELY PERSIST ALONG/SOUTH OF THE
QLCS-OUTFLOW BOUNDARY INTERSECTION. WHILE LOCAL TEMPORAL EXTENSIONS
/UP TO 1-2 HR/ MAY NEED TO BE CONSIDERED FOR WW 16...AN ADDITIONAL
WATCH IS NOT OTHERWISE ANTICIPATED.

..GUYER.. 01/26/2012

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

ATTN...WFO...JAN...LIX...LCH...

LAT...LON   28509294 29579239 30939189 31229099 32168998 32288942
            29189038 28509294

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 26, 2:05 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Iberia, Jefferson, Lafourche, Livingston and 12 more	2 hr
Jan 26, 4:18 AM CST	Tornado Watch	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 5 more	7 hr
Jan 26, 7:29 AM CST	Mesoscale Discussion	SPC	Plaquemines, Saint Bernard	91 min
Jan 26, 5:35 PM CST	Mesoscale Discussion	SPC	Alcorn, Clay, Itawamba, Lee, Lowndes, Monroe and 3 more	55 min

Nearby

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