Alert archive / Louisiana / Mesoscale Discussions in 2005

Mesoscale Discussion 2467

November 26, 2005Cameron Parish, Iberia Parish, Vermilion Parish, Louisiana; Galveston County, Jefferson County, Texas

The Storm Prediction Center issued this mesoscale discussion at Nov 26, 2005, 10:05 AM CST for Cameron Parish, Iberia Parish, Vermilion Parish, Louisiana; Galveston County, Jefferson County, Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Nov 26, 2005, 10:05 AM CST (16:05 UTC)
Expired: Nov 26, 2005, 12:30 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Cameron Parish, LA, Iberia Parish, LA, Vermilion Parish, LA, Galveston County, TX, Jefferson County, TX

The radar

The Lake Charles radar (KLCH), 112 km from the middle of the area, began a volume at 16:07 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 874Nov 26, 1:05 PM CST

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 4.1 hours before the alert went out and 112 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: 79 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 822 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 69 m²/s²
0-3 km storm-relative helicity: 55 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.

000 
ACUS11 KWNS 261605
SWOMCD
SPC MCD 261605 
LAZ000-TXZ000-261830-

MESOSCALE DISCUSSION 2467
NWS STORM PREDICTION CENTER NORMAN OK
1005 AM CST SAT NOV 26 2005

AREAS AFFECTED...COASTAL SE TX...PORTIONS SWRN/S-CENTRAL LA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 261605Z - 261830Z

SLGT POTENTIAL FOR SEVERE WILL DEVELOP ALONG COASTAL AREAS BETWEEN
GLS-LFT THROUGH EARLY AFTERNOON...WITH A TORNADO OR TWO POSSIBLE
ALONG WITH ISOLATED DAMAGING WIND.

SFC MESOANALYSIS SHOWS WEAK FRONTAL-WAVE LOW OFFSHORE PORT MANSFIELD
TX.  COMBINED FRONTAL ZONE AND OUTFLOW/CONVECTIVE BOUNDARY EXTENDS
NEWD TOWARD GLS...THEN MARINE/WARM FRONT IS ANALYZED JUST OFFSHORE
FROM CHAMBERS COUNTY EWD ACROSS COASTAL WATERS CAMERON/VERMILION/ST
MARY/IBERIA PARISHES.  LOOSELY ORGANIZED MCS ALONG AND BEHIND
OUTFLOW BOUNDARY WILL CONTINUE TO MOVE EWD ACROSS COASTAL AREAS
THROUGH AFTERNOON.  MARINE FRONT SHOULD DRIFT NWD INTO EARLY
AFTERNOON AND MAY MOVE ONSHORE BRIEFLY BEFORE LEADING EDGE OF MCS
MOVES THROUGH. MODIFIED RAOBS AND RUC SOUNDINGS INDICATE SFC-BASED
BUOYANCY ALONG AND S OF MARINE FRONT GIVEN AND DEW POINTS MID 60S
NOW OBSERVED IN THAT AIR MASS...AND COMBINED WAA/INSOLATION RELATED
HEATING OF SFC TEMPS INTO LOW 70S.
STRONGER LARGE SCALE FORCING/ASCENT REMAINS ALONG/BEHIND OUTFLOW
BOUNDARY...SO LAPSE RATES OVER MARINE AIR SHOULD REMAIN
WEAK....LIMITING MLCAPES UNDER 750 J/KG MOST AREAS.  PARCELS N OF
WARM FRONT WILL REMAIN SLIGHTLY ELEVATED BECAUSE OF PRONOUNCED
STABLE LAYER NEAR SFC...KEEPING SEVERE POTENTIAL LARGELY ALONG/S OF
FRONT.

DEEP-LAYER SPEED SHEAR -- NOW OPTIMIZED ACROSS UPPER TX COAST PER
VWP/PROFILER DATA AND RUC ANALYSES -- WILL INCREASE WITH TIME
FARTHER E ACROSS SWRN/S-CENTRAL LA AS MID/UPPER LEVEL PERTURBATION
APCHS. ALTHOUGH HODOGRAPH SIZE IS LIMITED BY LACK OF DIRECTIONAL
SHEAR IN LOW LEVELS...CELLS MAY ROTATE.  SUSTAINED SUPERCELL
PROBABILITIES ARE HIGHER FOR TSTMS MOVING ONSHORE FROM GULF THAN EWD
IN MCS BECAUSE OF SOMEWHAT MORE DISCRETE MODE.

..EDWARDS.. 11/26/2005

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

ATTN...WFO...LCH...HGX...

28339545 29049506 29689460 30009391 29929233 29729162
29479147 29319163 29169204 29059304 28789396 28149486

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 26, 1:07 PM CST	Tornado Watch	SPC	Acadia, Calcasieu, Cameron, Iberia, Jefferson Davis, Lafayette and 3 more	5 hr
Nov 26, 2:25 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Iberia, Iberville, Jefferson, Lafayette and 12 more	2 hr
Nov 25, 10:50 PM CST	Mesoscale Discussion	SPC	Atascosa, Bandera, Bee, Bexar, Comal, DeWitt and 13 more	115 min

Nearby

Mesoscale Discussions in Louisiana, 2005 Mesoscale Discussions in Texas, 2005 Every mesoscale discussion in 2005

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.