Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 98

February 3, 201212 parishes in Louisiana; 4 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 3, 2012, 6:35 AM CST for 12 parishes in Louisiana; 4 counties in Texas. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Feb 3, 2012, 6:35 AM CST (12:35 UTC)
Expired: Feb 3, 2012, 8:30 AM CST
In force: 115 min
Issued by: the Storm Prediction Center

Counties Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Jasper County, TX, Newton County, TX, Sabine County, TX, Tyler County, TX

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 0.6 hours before the alert went out and 94 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: 844 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 448 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 132 m²/s²
0-3 km storm-relative helicity: 216 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

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

529 
ACUS11 KWNS 031235
SWOMCD
SPC MCD 031235 
MSZ000-LAZ000-TXZ000-031430-

MESOSCALE DISCUSSION 0098
NWS STORM PREDICTION CENTER NORMAN OK
0635 AM CST FRI FEB 03 2012

AREAS AFFECTED...PORTIONS SE TX...CENTRAL-SWRN LA...EXTREME SWRN MS.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 031235Z - 031430Z

MRGL/SPORADIC SVR THREAT IS EVIDENT OVER DISCUSSION AREA...HOWEVER
WW IS NOT ANTICIPATED DURING NEXT COUPLE HOURS.  ISOLATED DAMAGING
GUSTS ARE POSSIBLE...WITH CONDITIONAL/BRIEF TORNADO POTENTIAL.  13Z
DAY-1 OUTLOOK ACCORDINGLY WILL REFLECT SVR PROBABILITIES EXTENDED
SEWD INTO AREA...BOTH FOR ONGOING ACTIVITY AND FOR LATE-PERIOD
POTENTIAL.  RAIN RATES 2-3 INCHES/HOUR ALSO WILL BE POSSIBLE FROM
MOST INTENSE CORES...GIVEN EFFICIENT PRECIP PROCESSING ON STORM
SCALE AND HIGH PW IN INFLOW ENVIRONMENT.

SFC MESOANALYSIS SHOWS FRONTAL ZONE...ITS BAROCLINICITY REINFORCED
BY PERSISTENT CONVECTION TO ITS N...FROM NEAR MSY-BTR-ACP-JAS. 
FRONT SHOULD CONTINUE TO DRIFT NWD.  FRONTAL ZONE BECOMES DIFFUSE
FARTHER NW OVER TX WHERE BROAD WAA PLUME AND OTHER SYNOPTIC-SCALE
PROCESSES OF ROCKIES CYCLONE ARE MORE DOMINANT.  WIDESPREAD PRECIP
AND EMBEDDED TSTMS ALONG AND N OF SE TX/LA FRONTAL SEGMENT ARE FCST
TO CONTINUE THROUGH AT LEAST MID-MORNING.  ACTIVITY SHOULD SHIFT
GENERALLY NEWD TO ENEWD IN REGIME OF RICH LOW-LEVEL MOISTURE BUT
INITIALLY WEAK LOW-MIDLEVEL LAPSE RATES.  12Z LCH RAOB AND MODIFIED
RUC SOUNDINGS SUGGEST MLCAPE RANGING FROM AROUND 1000 J/KG NEAR I-10
TO LESS THAN 250 J/KG ALONG AND JUST N OF FRONT..BUT WITH SFC-BASED
EFFECTIVE INFLOW PARCELS.  INSOLATION SHOULD BOOST THESE VALUES BY
25-50% BY LATE MORNING...HELPING TO REMOVE REMAINING CINH. 
DEEP-LAYER SHEAR WILL REMAIN WEAK...BUT WITH AT LEAST MRGLLY
FAVORABLE BOUNDARY-LAYER SHEAR...INDICATING POTENTIAL FOR TRANSIENT
CIRCULATIONS EITHER WITH SMALLER/DISCRETE CELLS OR BOWING CLUSTERS. 
OBSERVED RAOB/VWP DATA AND FCST SOUNDINGS SUGGEST 100-200 J/KG OF
0-1 KM AGL SRH...BUT ONLY 20-30 KT EFFECTIVE SHEAR MAGNITUDE.  MAIN
CONTRIBUTOR TO DAMAGING DOWNDRAFT POTENTIAL WILL BE STORM-SCALE
PRECIP LOADING.

..EDWARDS.. 02/03/2012

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

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

LAT...LON   30689483 31549375 31739309 31889181 31399127 30789165
            30199291 30419387 30329507 30689483

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 3, 1:04 PM CST	Mesoscale Discussion	SPC	East Feliciana, Evangeline, Pointe Coupee, Saint Helena, West Feliciana	116 min
Feb 2, 7:08 PM CST	Mesoscale Discussion	SPC	Baylor, Childress, Collingsworth, Cottle, Crosby, Dickens and 10 more	67 min
Feb 2, 7:38 PM CST	Severe Thunderstorm Watch	SPC	Armstrong, Bailey, Briscoe, Carson, Castro, Childress and 24 more	7 hr
Feb 2, 9:48 PM CST	Mesoscale Discussion	SPC	Armstrong, Briscoe, Carson, Childress, Collingsworth, Cottle and 16 more	117 min
Feb 2, 11:44 PM CST	Mesoscale Discussion	SPC	Armstrong, Briscoe, Carson, Childress, Collingsworth, Cottle and 11 more	91 min
Feb 3, 2:00 AM CST	Mesoscale Discussion	SPC	Briscoe, Childress, Collingsworth, Cottle, Donley, Floyd and 6 more	60 min
Feb 3, 2:25 AM CST	Tornado Watch	SPC	Childress, Collingsworth, Hardeman, Wheeler, Wilbarger	8 hr
Feb 3, 7:15 AM CST	Mesoscale Discussion	SPC	Childress, Collingsworth, Cottle, Hall, Hardeman, Wilbarger	90 min
Feb 3, 9:42 AM CST	Mesoscale Discussion	SPC	Hardeman	63 min
Feb 3, 11:59 AM CST	Mesoscale Discussion	SPC	Archer, Clay, Cooke, Jack, Montague, Palo Pinto and 6 more	91 min
Feb 3, 12:26 PM CST	Tornado Watch	SPC	Archer, Clay, Cooke, Denton, Grayson, Jack and 7 more	8 hr
Feb 3, 3:17 PM CST	Mesoscale Discussion	SPC	Clay, Cooke, Denton, Grayson, Jack, Montague and 4 more	88 min
Feb 3, 5:41 PM CST	Mesoscale Discussion	SPC	Brown, Collin, Comanche, Cooke, Dallas, Denton and 17 more	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Texas, 2012 Every 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.