Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 2126
The Storm Prediction Center issued this mesoscale discussion at Nov 26, 2012, 10:14 PM CST for 4 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 26, 2012, 10:14 PM CST (04:14 UTC)
- Expired
- Nov 27, 2012, 12:45 AM CST
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 60 counties
Ashley County, AR, Chicot County, AR, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Hinds County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Sharkey County, MS, Warren County, MS, Washington County, MS, Wilkinson County, MS, Yazoo County, MS, Angelina County, TX, Chambers County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Tyler County, TX
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.2 hours before the alert went out and 132 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.
- Mixed-layer CAPE
- 1589 J/kg
- Mixed-layer CIN
- -6 J/kg
- Mixed-layer LCL
- 658 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 115 m²/s²
- 0-3 km storm-relative helicity
- 82 m²/s²
- Significant tornado parameter
- 0.7
- Supercell composite
- 3.8
The text
As transmitted, in the capitals the NWS used until 2016.
478
ACUS11 KWNS 270415
SWOMCD
SPC MCD 270414
MSZ000-LAZ000-ARZ000-TXZ000-270645-
MESOSCALE DISCUSSION 2126
NWS STORM PREDICTION CENTER NORMAN OK
1014 PM CST MON NOV 26 2012
AREAS AFFECTED...SERN TX...CNTRL/NRN/WRN LA...PARTS OF FAR SRN
AR...CNTRL/SWRN MS
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 270414Z - 270645Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A THREAT FOR ISOLATED MARGINALLY SVR HAIL MAY PERSIST INTO
THE OVERNIGHT HOURS...AND THE ISSUANCE OF A WW IS UNLIKELY.
DISCUSSION...THE OVERALL SVR THREAT APPEARS TO BE DIMINISHING AHEAD
OF A FRONT THAT LIES APPROXIMATELY FROM S-CNTRL TX TO E OF
SHREVEPORT TO E OF GREENVILLE MS. DESPITE RICH LOW-LEVEL MOISTURE
CHARACTERIZED BY MIDDLE 60S DEWPOINTS...NOCTURNAL COOLING IS
MINIMIZING BOUNDARY-LAYER INSTABILITY. WHILE CLUSTERS OF STORMS
CONTINUE DEVELOPING NEAR AND AHEAD OF THE FRONT...APPRECIABLE
MID-LEVEL ASCENT IS LACKING...AS THE PRIMARY SRN-STREAM VORT MAX
LAGS BACK ACROSS THE LOWER RIO GRANDE VALLEY. WITH CONTINUED
NOCTURNAL STABILIZATION... STORM INTENSITY WILL BE HINDERED AMIDST
ONLY MODEST DEEP SHEAR -- I.E. 20-35 KT OF EFFECTIVE BULK SHEAR.
REGARDLESS...A FEW INSTANCES OF MARGINALLY SVR HAIL CANNOT BE RULED
OUT WITH THE MOST INTENSE...DISCRETE/SEMI-DISCRETE STORMS. A FEW
STORMS EAST OF AN INCREASINGLY ILL-DEFINED WARM FRONT/CONFLUENCE
AXIS HAVE OCCASIONALLY EXHIBITED WEAK STORM-SCALE ROTATION ACROSS
N-CNTRL/NERN LA -- A MANIFESTATION OF RELATIVELY GREATER LOW-LEVEL
DIRECTIONAL SHEAR PER VWP DATA. HOWEVER...THE THERMODYNAMIC
ENVIRONMENT NEAR AND DOWNSTREAM OF THIS ACTIVITY WILL NOT BE
CONDUCIVE FOR ANY SVR THREAT ASIDE FROM ISOLATED MARGINALLY SVR
HAIL.
..COHEN/DARROW.. 11/27/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LIX...LZK...LCH...SHV...HGX...
LAT...LON 30399585 31649430 32519339 33249239 33299051 32519000
31809034 31069138 30669197 30109320 29589492 29789595
30399585SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 26, 6:44 PM CST | Mesoscale Discussion | SPC | Union | 91 min |
Nearby
Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Mississippi, 2012Every 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.