Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 83

February 1, 201211 parishes in Louisiana; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 1, 2012, 1:06 AM CST for 11 parishes in Louisiana; 5 counties in Mississippi. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Feb 1, 2012, 1:06 AM CST (07:06 UTC)
Expired: Feb 1, 2012, 3:00 AM CST
In force: 114 min
Issued by: the Storm Prediction Center

Counties Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Pointe Coupee Parish, LA, Saint Landry Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Franklin County, MS, Lincoln County, MS, Wilkinson County, MS

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 7.1 hours before the alert went out and 137 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: 251 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 710 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 90 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

484 
ACUS11 KWNS 010706
SWOMCD
SPC MCD 010706 
MSZ000-LAZ000-010900-

MESOSCALE DISCUSSION 0083
NWS STORM PREDICTION CENTER NORMAN OK
0106 AM CST WED FEB 01 2012

AREAS AFFECTED...SWRN LA TO SWRN MS

CONCERNING...01Z OUTLOOK UPGRADE 

VALID 010706Z - 010900Z

A MARGINAL RISK FOR A BRIEF TORNADO AND DAMAGING WINDS EXISTS WITHIN
A CLUSTER OF TSTMS EXTENDING NEWD FROM SWRN LA. A WW ISSUANCE IS NOT
ANTICIPATED ATTM.

SW TO NE BAND OF TSTMS FROM CALCASIEU TO AVOYELLES PARISH LA APPEARS
LIKELY TO PERSIST WITHIN AN AXIS OF CONFLUENCE AMIDST A MODEST
LOW-LEVEL WAA REGIME. THIS SCENARIO IS SUPPORTED BY 00Z WRF-NSSL/NMM
GUIDANCE. EMBEDDED CELL IN ALLEN/EVANGELINE COUNTIES HAS SHOWN
EVIDENCE OF LOW-LEVEL ROTATION OVER THE PAST HALF HOUR. ALTHOUGH
LOW-LEVEL S/SWLYS ARE NOT PARTICULARLY STRONG AND NOT EXPECTED TO
STRENGTHEN...0-1 KM SRH OF 100-150 M2/S2 APPEARS TO BE ADEQUATE FOR
UPDRAFT ROTATION. GIVEN PRESENCE OF A RICH/MOIST THERMODYNAMIC
PROFILE CHARACTERIZED BY SURFACE DEW POINTS/TEMPERATURE IN THE
MIDDLE/UPPER 60S...A RISK FOR ISOLATED DAMAGING WINDS AND A BRIEF
TORNADO MAY PERSIST FOR THE NEXT FEW HOURS.

..GRAMS.. 02/01/2012

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

ATTN...WFO...JAN...LIX...LCH...

LAT...LON   30179359 30679293 31319180 31749103 31819069 31629043
            31329046 30689107 29809299 29779366 30179359

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 1, 10:18 AM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 6 more	117 min
Feb 1, 12:37 PM CST	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Claiborne, Lincoln, Union and 1 more	5 hr
Feb 1, 1:22 PM CST	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Union, Webster	113 min
Feb 1, 1:36 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 12 more	84 min
Feb 1, 2:58 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Claiborne, Lincoln, Morehouse, Union and 2 more	2 hr
Feb 1, 3:45 PM CST	Severe Thunderstorm Watch	SPC	East Carroll, Morehouse, West Carroll	3 hr
Feb 1, 5:18 PM CST	Mesoscale Discussion	SPC	Ascension, Livingston, Orleans, Saint Charles, Saint James, Saint John the Baptist and 2 more	87 min
Feb 1, 4:49 PM CST	Mesoscale Discussion	SPC	Attala, Benton, Calhoun, Carroll, Chickasaw, Choctaw and 17 more	56 min
Feb 1, 4:59 PM CST	Severe Thunderstorm Watch	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 21 more	4 hr

Nearby

Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Mississippi, 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.