Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 91

February 6, 201122 parishes in Louisiana; Issaquena County, Mississippi; 6 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 6, 2011, 8:16 PM CST for 22 parishes in Louisiana; Issaquena County, Mississippi; 6 counties in Texas. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Feb 6, 2011, 8:16 PM CST (02:16 UTC)
Expired: Feb 6, 2011, 10:15 PM CST
In force: 119 min
Issued by: the Storm Prediction Center

All 29 counties

Allen Parish, LA, Beauregard Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Issaquena County, MS, Hardin County, TX, Jasper County, TX, Liberty County, TX, Newton County, TX, Sabine County, TX, Tyler County, TX

The nearest sounding before it

Shreveport, LA (KSHV), launched 00:00Z, 2.3 hours before the alert went out and 134 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: 16 J/kg
Mixed-layer CIN: -103 J/kg
Mixed-layer LCL: 1921 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 150 m²/s²
0-3 km storm-relative helicity: 242 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.

833 
ACUS11 KWNS 070217
SWOMCD
SPC MCD 070216
MSZ000-LAZ000-ARZ000-TXZ000-070415-

MESOSCALE DISCUSSION 0091
NWS STORM PREDICTION CENTER NORMAN OK
0816 PM CST SUN FEB 06 2011

AREAS AFFECTED...SE TX INTO LA AND ADJACENT PORTIONS OF SRN AR...WRN
MS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 070216Z - 070415Z

THUNDERSTORMS MAY CONTINUE ANOTHER FEW HOURS...BUT THEY ARE NOT
EXPECTED TO INTENSIFY MUCH FURTHER.

VERY STEEP LOW-LEVEL LAPSE RATES...WHERE SURFACE HEATING BECAME
MAXIMIZED IN A PRE-FRONTAL TONGUE FROM SOUTH CENTRAL TEXAS INTO THE
ARKLATEX...ARE SLOWLY BEGINNING TO STABILIZE WITH RADIATIONAL
SURFACE COOLING AND THE SOUTHEASTWARD ADVANCEMENT OF THE COLD FRONT.
AS THIS PROCESS CONTINUES...THE VIGOR OF THE EVOLVING NARROW SQUALL
LINE NOW SPREADING THROUGH THE SABINE VALLEY IS EXPECTED TO DECREASE
WITHIN THE NEXT HOUR OR TWO...AND STORMS ON THE SOUTHERN FLANK OF
THE LINE MAY DISSIPATE ALTOGETHER BY AROUND 04Z.  FARTHER
NORTH...STRONGER MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION IN THE
EXIT REGION OF A STRENGTHENING MID-LEVEL JET STREAK ACROSS SOUTHEAST
TEXAS MAY MAINTAIN THUNDERSTORM ACTIVITY A BIT LONGER...EASTWARD
ACROSS NORTHERN LOUISIANA...PERHAPS INTO PARTS OF WEST CENTRAL
MISSISSIPPI BY 06-07Z.  HOWEVER...THE RISK FOR GUSTY WINDS AND SMALL
HAIL PROBABLY WILL DIMINISH IN A PROGRESSIVELY COOLER/LESS UNSTABLE
ENVIRONMENT.

..KERR.. 02/07/2011

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

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

LAT...LON   30109500 31489387 31789320 32479272 33019234 33079096
            32159087 31529143 30619287 29809462 30109500

Nearby

Mesoscale Discussions in Louisiana, 2011 Mesoscale Discussions in Texas, 2011 Mesoscale Discussions in Mississippi, 2011 Every mesoscale discussion in 2011

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.