Alert archive / Louisiana / Mesoscale Discussions in 2008

Mesoscale Discussion 2313

October 7, 200817 parishes in Louisiana; 13 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Oct 7, 2008, 7:47 AM CDT for 17 parishes in Louisiana; 13 counties in Texas. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Oct 7, 2008, 7:47 AM CDT (12:47 UTC)
Expired: Oct 7, 2008, 9:15 AM CDT
In force: 88 min
Issued by: the Storm Prediction Center

All 30 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Vernon Parish, LA, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Newton County, TX, Orange County, TX, Tyler County, TX

The radar

The Lake Charles radar (KLCH), 86 km from the middle of the area, began a volume at 12:49 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 12:00Z, 0.8 hours before the alert went out and 88 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: 2713 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 474 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 91 m²/s²
0-3 km storm-relative helicity: 101 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 5.2

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 071247
SWOMCD
SPC MCD 071247 
LAZ000-TXZ000-071415-

MESOSCALE DISCUSSION 2313
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT TUE OCT 07 2008

AREAS AFFECTED...FAR SOUTHEAST TX INTO LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 071247Z - 071415Z

AT LEAST AN ISOLATED SEVERE RISK MAY INCREASE THROUGH THE MORNING
ACROSS FAR SOUTHEAST TX INTO LA. THE NEED FOR A WATCH IN THE SHORT
TERM IS UNCLEAR...BUT CONVECTIVE TRENDS WILL BE CLOSELY MONITORED
FOR A POSSIBLE WATCH.

30-KT EAST-MOVING/NORTHEAST-SOUTHWEST ORIENTED CONVECTIVE LINE
ACROSS FAR SOUTHEAST TX HAS INTENSIFIED TO A DEGREE OVER THE PAST
HOUR...WITH SOME MODEST BOWING NORTHEAST OF THE HOUSTON AREA EARLY
THIS MORNING. GIVEN A VERY MOIST DOWNSTREAM AIRMASS WITH LOW TO MID
70S F DEWPOINTS AND GRADUAL HEATING THROUGH THE MORNING...POTENTIAL
WILL EXIST FOR THIS CONVECTIVE LINE AND/OR LEADING MORE DISCRETE
DEVELOPMENT TO INTENSIFY THROUGH THE MORNING ACROSS FAR SOUTHEAST
TX/MUCH OF LA. OBSERVED 12Z RAOBS FROM LAKE CHARLES/NEW ORLEANS
REFLECT MODERATE BUOYANCY AND ONLY WEAK INHIBITION...WITH MODIFIED
VERSIONS OF THESE SOUNDINGS IMPLYING AN INCREASING POTENTIAL FOR
WIND DAMAGE /AND PERHAPS A TORNADO/ AS TEMPERATURES DIURNALLY WARM
THROUGH THE 80S F TODAY. MORNING RAOBS/WSR-88D DERIVED WINDS SUGGEST
VERTICAL SHEAR BECOMES MORE MARGINAL WITH SOUTH EXTENT ACROSS
SOUTHEAST TX/LA...BUT AROUND 30-35 KT OF EFFECTIVE BULK SHEAR WILL
CONTRIBUTE TO QUASI-ORGANIZED MAINLY MULTICELLULAR/LINEAR
ORGANIZATION.

..GUYER.. 10/07/2008

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

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

31119398 31999330 31839163 29899211 29539424 28549606
29409621 30289498

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 7, 11:24 AM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Avoyelles, Catahoula, Concordia and 27 more	3 hr

Nearby

Mesoscale Discussions in Louisiana, 2008 Mesoscale Discussions in Texas, 2008 Every mesoscale discussion in 2008

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.