Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 576

April 20, 201212 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2012, 7:30 PM CDT for 12 parishes in Louisiana. It was in force for 30 min.

The area

The outline as issued.

The facts

Issued
Apr 20, 2012, 7:30 PM CDT (00:30 UTC)
Expired
Apr 20, 2012, 8:00 PM CDT
In force
30 min
Issued by
the Storm Prediction Center

Counties Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Cameron Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Vernon Parish, LA, Winn Parish, LA

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 0.5 hours before the alert went out and 150 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 2012-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 629 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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 2012-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -10 square meters per square second.193958Sfc1 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
629 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
988 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
-10 m²/s²
0-3 km storm-relative helicity
18 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.

054 
ACUS11 KWNS 210031
SWOMCD
SPC MCD 210030
LAZ000-210100-

MESOSCALE DISCUSSION 0576
NWS STORM PREDICTION CENTER NORMAN OK
0730 PM CDT FRI APR 20 2012

AREAS AFFECTED...SERN AND CENTRAL LA

CONCERNING...SEVERE THUNDERSTORM WATCH 184...

VALID 210030Z - 210100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 184
CONTINUES.

SEVERE THREAT DIMINISHING ACROSS SWRN LA.

LATEST RADAR LOOP SHOWS STORMS WEAKENING/BECOMING INCREASINGLY
DISORGANIZED WITH TIME AS THEY MOVE ACROSS WESTERN LA...ACROSS FAR
ERN PORTIONS OF THE WW.  THE WATCH IS SET TO EXPIRE AT THE TOP OF
THE HOUR -- 21/01Z -- AND WITH LITTLE REMAINING SEVERE THREAT
EVIDENT AS THE AIRMASS DIURNALLY STABILIZES...NEW WW WILL LIKELY NOT
BE NEEDED.

..GOSS.. 04/21/2012

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

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

LAT...LON   32139262 31889190 30749198 29759328 31699349 32139262

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.