Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 2104
The Storm Prediction Center issued this mesoscale discussion at Nov 5, 2012, 7:35 PM CST for 33 parishes in Louisiana; 4 counties in Mississippi; 8 counties in Texas. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Nov 5, 2012, 7:35 PM CST (01:35 UTC)
- Expired
- Nov 5, 2012, 9:30 PM CST
- In force
- 115 min
- Issued by
- the Storm Prediction Center
All 45 counties
Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, West Baton Rouge Parish, LA, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Brazoria County, TX, Chambers County, TX, Galveston County, TX, Hardin County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Orange County, TX
The radar
The Lake Charles radar (KLCH), 123 km from the middle of the area, began a volume at 01:36 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 00:00Z, 1.6 hours before the alert went out and 121 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
- 1567 J/kg
- Mixed-layer CIN
- -17 J/kg
- Mixed-layer LCL
- 782 m above ground
- 0-6 km bulk shear
- 62 kt
- 0-1 km storm-relative helicity
- -80 m²/s²
- 0-3 km storm-relative helicity
- 3 m²/s²
- Significant tornado parameter
- -0.2
- Supercell composite
- -0.6
The text
As transmitted, in the capitals the NWS used until 2016.
069
ACUS11 KWNS 060135
SWOMCD
SPC MCD 060135
MSZ000-LAZ000-TXZ000-060330-
MESOSCALE DISCUSSION 2104
NWS STORM PREDICTION CENTER NORMAN OK
0735 PM CST MON NOV 05 2012
AREAS AFFECTED...PARTS OF SERN TX...SRN LA...EXTREME SERN MS
CONCERNING...SEVERE THUNDERSTORM WATCH 673...674...
VALID 060135Z - 060330Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
673...674...CONTINUES.
SUMMARY...THE THREAT FOR SVR TSTMS CONTINUES ACROSS WW674 AND
REMAINING VALID PORTIONS OF WW673.
DISCUSSION...LATEST SFC MESOANALYSIS DEPICTS A DIFFUSE FRONTAL
BOUNDARY LYING FROM S OF GULFPORT MS TO A FRONTAL INFLECTION NW OF
BATON ROUGE LA. THE BOUNDARY BECOMES LESS BAROCLINIC WITH WWD EXTENT
INTO S-CNTRL TX...WHERE IT ALIGNS WITH A NOTABLE WIND-SHIFT AXIS
THAT LEADS A STRONGER COLD FRONT APPROACHING FROM THE NW. STORMS
CONTINUE ALONG/AHEAD OF THE COLD FRONT OVER THE COASTAL PLAIN
ADJACENT TO THE UPPER TX AND SWRN LA COASTS. MODIFICATIONS TO THE
LAKE CHARLES 00Z RAOB TO MITIGATE WET-BULBING EFFECTS WOULD SUGGEST
1000-1500 J/KG OF MLCAPE AMIDST AROUND 60 KT OF EFFECTIVE BULK SHEAR
TO SUPPORT ORGANIZED STORMS WITH SVR HAIL/WIND ACROSS REMAINING
VALID PORTIONS OF WW673. WW673 SHOULD BE ALLOWED TO EXPIRE ON
SCHEDULE AT 03Z AS STORMS MOVE OFF THE COAST.
FARTHER EAST ACROSS THE WARM SECTOR INTO S-CNTRL/SERN LA...A RECENT
UPTICK IN CONVECTION HAS BEEN NOTED NEAR AND WEST OF LAKE
PONTCHARTRAIN IN CONCERT WITH INCREASING FORCING FOR ASCENT LEADING
AN UPSTREAM MID-LEVEL VORT MAX. THIS ACTIVITY WILL SHIFT ESEWD
THROUGH THE EVENING...PERHAPS REACHING THE NEW ORLEANS AREA DURING
THE NEXT COUPLE OF HOURS. UNIDIRECTIONAL FLOW THROUGH THE CLOUD
LAYER WITH A 0-6-KM BULK SHEAR MAGNITUDE OF 71 KT PER SLIDELL VWP
DATA WILL CONTINUE TO FOSTER DISCRETE/SEMI-DISCRETE SUPERCELL
STRUCTURES WITH SVR HAIL AND POSSIBLY SVR WIND GUSTS. MODEST
DIRECTIONAL SHEAR IN THE LOWEST 1-KM AGL MAY YIELD A BRIEF TORNADO
THOUGH RELATIVELY MORE MARGINAL BUOYANCY WITH EWD EXTENT ACROSS THE
WARM SECTOR SHOULD MITIGATE THIS THREAT.
..COHEN.. 11/06/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MOB...LIX...LCH...HGX...
LAT...LON 30478850 29948834 29398850 28758897 28749012 29019137
29249263 29279377 28729505 28659588 28889612 29239604
29739553 30339457 30659361 30859219 30859018 30728911
30478850SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 5, 9:33 PM CST | Mesoscale Discussion | SPC | Jefferson, Lafourche, Plaquemines, Terrebonne | 57 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; radar from the NEXRAD Level II archive.