Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 448

April 4, 201227 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 4, 2012, 8:25 PM CDT for 27 parishes in Louisiana. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
Apr 4, 2012, 8:25 PM CDT (01:25 UTC)
Expired
Apr 4, 2012, 10:00 PM CDT
In force
95 min
Issued by
the Storm Prediction Center
All 27 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette 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, Vermilion Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA

The radar

The Lake Charles radar (KLCH), 133 km from the middle of the area, began a volume at 01:29 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

Lake Charles Mun, LA (KLCH), launched 00:00Z, 1.4 hours before the alert went out and 131 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-pSkew-T log-p diagram, Lake Charles Mun, LA at 00:00Z on 2012-04-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2323 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lake Charles Mun, LA at 00:00Z on 2012-04-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -30 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
2323 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
739 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
-30 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

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

371 
ACUS11 KWNS 050125
SWOMCD
SPC MCD 050125 
LAZ000-MSZ000-050300-

MESOSCALE DISCUSSION 0448
NWS STORM PREDICTION CENTER NORMAN OK
0825 PM CDT WED APR 04 2012

AREAS AFFECTED...SRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 050125Z - 050300Z

A SEVERE THREAT MAY DEVELOP ACROSS SRN LA WITH STORMS EXPECTED TO
INCREASE IN COVERAGE OVER THE NEXT FEW HOURS. ISOLATED LARGE HAIL
AND WIND DAMAGE WILL BE POSSIBLE. ALTHOUGH THE THREAT SHOULD REMAIN
ISOLATED...WW ISSUANCE CAN NOT BE RULED OUT ACROSS THE REGION THIS
EVENING.

A LINE OF STRONG THUNDERSTORMS CURRENTLY EXTENDS FROM NEAR LAKE
CHARLES SWD OFF THE LA COAST ABOUT 150 STATUTE MILES. THIS LINE IS
ASSOCIATED WITH A MINOR SHORTWAVE TROUGH OVER THE NW GULF OF MEXICO
AND IS LOCATED ALONG AN AXIS OF STRONG INSTABILITY EXTENDING ENEWD
ACROSS SCNTRL LA. THE 00Z SOUNDING FROM LAKE CHARLES SHOWS AN MLCAPE
OF 2500 J/KG WITH 0-6 KM SHEAR OF 40 TO 45 KT. THIS ENVIRONMENT
ALONG WITH A 700-500 MB LAPSE RATES NEAR 8.0 C/KM SHOULD SUPPORT
LARGE HAIL. ALTHOUGH...LOW-LEVEL LAPSE RATES ARE ALSO
STEEP...BOUNDARY LAYER FLOW IS WEAK SUGGESTING ANY WIND DAMAGE
THREAT MAY BE MARGINAL. AS LOW-LEVEL FLOW INCREASES LATER THIS
EVENING ACROSS SRN LA...THE WIND DAMAGE THREAT COULD BECOME MORE
SUBSTANTIAL ACROSS THE ERN PART OF THE MCD AREA IF A CLUSTER OF
STRONG THUNDERSTORMS CAN ORGANIZE AS IS SUGGESTED BY THE LATEST GFS
AND NAMKF SOLUTIONS.

..BROYLES.. 04/05/2012

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

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

LAT...LON   29549037 29289186 29729327 30039363 30479362 30689336
            30899289 31109156 31009090 30749023 30149008 29549037

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 4, 8:31 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Lincoln and 2 more119 min
Apr 5, 1:35 AM CDTMesoscale DiscussionSPCAvoyelles, Caldwell, Catahoula, Concordia, East Baton Rouge, East Carroll and 21 more85 min
Apr 5, 1:53 AM CDTTornado WatchSPCAcadia, Allen, Ascension, Avoyelles, Bienville, Caldwell and 36 more9 hr
Apr 5, 3:30 AM CDTMesoscale DiscussionSPCAcadia, Ascension, Assumption, Avoyelles, Caldwell, Catahoula and 43 more2 hr
Apr 5, 3:56 AM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more6 hr
Apr 5, 7:36 AM CDTMesoscale DiscussionSPCCaldwell, Catahoula, Concordia, East Carroll, Franklin, Jackson and 18 more54 min

Nearby

Mesoscale Discussions in Louisiana, 2012Every 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.