Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 1913

October 31, 201528 parishes in Louisiana; 22 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Oct 31, 2015, 5:42 PM CDT for 28 parishes in Louisiana; 22 counties in Mississippi. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Oct 31, 2015, 5:42 PM CDT (22:42 UTC)
Expired: Oct 31, 2015, 7:15 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 50 counties

Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans 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, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Hancock County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Simpson County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 10.7 hours before the alert went out and 144 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 847 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 292 m²/s²
0-3 km storm-relative helicity: 361 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.

112 
ACUS11 KWNS 312243
SWOMCD
SPC MCD 312242 
ALZ000-MSZ000-LAZ000-010015-

MESOSCALE DISCUSSION 1913
NWS STORM PREDICTION CENTER NORMAN OK
0542 PM CDT SAT OCT 31 2015

AREAS AFFECTED...SRN LA...SRN MS

CONCERNING...TORNADO WATCH 528...

VALID 312242Z - 010015Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 528 CONTINUES.

SUMMARY...A THREAT FOR TORNADOES AND WIND DAMAGE CURRENTLY IN SRN MS
WILL MOVE EWD INTO AL OVER THE NEXT 1 TO 2 HOURS. ALTHOUGH AN
ISOLATED SEVERE THREAT COULD LINGER IN FAR SRN MS...THE THREAT
SHOULD DIMINISH ENOUGH TO ALLOW THE WW TO EXPIRE AT 00Z.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A VERY MOIST AIRMASS IN
PLACE ACROSS SE LA EXTENDING NWD INTO SRN MS WHERE SFC DEWPOINTS ARE
IN THE LOWER TO MID 70S F. AN INTENSE LINE OF STORMS IS ONGOING
ALONG THE NRN EDGE OF THE MOIST AIRMASS FROM NEAR BILOXI MS NWD TO A
WARM FRONT LOCATED TO THE NORTHEAST OF MERIDIAN MS. THE LINE WILL
CONTINUE TO MOVE EWD AT 30 KT ALLOWING THE SEVERE THREAT TO
GRADUALLY DIMINISH FROM THE NORTH TO SOUTH ACROSS WAYNE...GREENE AND
JACKSON COUNTIES IN SRN MS OVER THE NEXT 1 TO 2 HOURS. FURTHER TO
THE SOUTHWEST ACROSS SRN LA...THE LINE HAS WEAKENED CONSIDERABLY AND
AN ORGANIZED SEVERE THREAT IS NOT EXPECTED TO REDEVELOP THIS
EVENING. FOR THESE REASONS...THE WW WILL LIKELY BE ALLOWED TO EXPIRE
AT 00Z.

..BROYLES/MEAD.. 10/31/2015

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

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

LAT...LON   29269304 31969147 31978839 29259004 29269304

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 31, 6:54 AM CDT	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more	5 hr
Oct 31, 10:03 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 8 more	57 min
Oct 31, 11:01 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, Avoyelles, East Baton Rouge, East Feliciana, Iberia and 18 more	89 min
Oct 31, 11:45 AM CDT	Tornado Watch	SPC	Acadia, Ascension, Assumption, Avoyelles, Cameron, Concordia and 27 more	8 hr
Oct 31, 1:35 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana and 22 more	55 min
Oct 31, 3:36 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana and 22 more	54 min

Nearby

Mesoscale Discussions in Louisiana, 2015 Mesoscale Discussions in Mississippi, 2015 Every mesoscale discussion in 2015

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.