Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 2144
The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2012, 8:38 PM CST for 4 states. It was in force for 67 min.
The area
The outline as issued.
The facts
- Issued
- Dec 9, 2012, 8:38 PM CST (02:38 UTC)
- Expired
- Dec 9, 2012, 9:45 PM CST
- In force
- 67 min
- Issued by
- the Storm Prediction Center
All 59 counties
Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Hempstead County, AR, Lafayette County, AR, Lincoln County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Union County, AR, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Bolivar County, MS, Angelina County, TX, Cherokee County, TX, Grimes County, TX, Hardin County, TX, Harrison County, TX, Houston County, TX, Jasper County, TX, Marion County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Panola County, TX, Polk County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX
The radar
The Shreveport radar (KSHV), 78 km from the middle of the area, began a volume at 02:40 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
Shreveport, LA (KSHV), launched 00:00Z, 2.6 hours before the alert went out and 83 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
- 928 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 874 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 161 m²/s²
- 0-3 km storm-relative helicity
- 192 m²/s²
- Significant tornado parameter
- 1.0
- Supercell composite
- 3.3
The text
As transmitted, in the capitals the NWS used until 2016.
834 ACUS11 KWNS 100239 SWOMCD SPC MCD 100238 MSZ000-ARZ000-LAZ000-TXZ000-100345- MESOSCALE DISCUSSION 2144 NWS STORM PREDICTION CENTER NORMAN OK 0838 PM CST SUN DEC 09 2012 AREAS AFFECTED...ERN/SERN TX...NWRN/WRN LA...SRN AR CONCERNING...SEVERE THUNDERSTORM WATCH 678... VALID 100238Z - 100345Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 678 CONTINUES. SUMMARY...TSTM ACTIVITY ALONG AND AHEAD OF A SEWD PROGRESSING COLD FRONT WILL CONTINUE TO POSE AT LEAST AN ISOLATED/BRIEF SEVERE WIND AND/OR HAIL THREAT DURING THE NEXT FEW HOURS. DISCUSSION...02Z SURFACE ANALYSIS PLACES THE COLD FRONT ALONG A LINE FROM PBF /IN SERN AR/ SWWD TO HYI /IN CNTRL TX/ AND THEN WSWWD TO THROUGH THE TX HILL COUNTRY. THIS SEWD MOVING COLD FRONT HAS OVERTAKEN MUCH OF THE TSTM ACTIVITY NOTED EARLIER ACROSS TX. HOWEVER...TSTMS ACROSS FAR E TX AND NWRN LA ARE STILL SLIGHTLY AHEAD OF THE FRONT AND LIKELY REMAIN SURFACE-BASED. AS SUCH...THERE IS STILL A MODEST SEVERE THREAT WITH THIS ACTIVITY...ESPECIALLY AS THE COLD FRONT MERGES WITH THE ONGOING STORMS AND PROVIDES BRIEF UPDRAFT INTENSIFICATION. THE PRIMARY THREAT IS FOR STRONG WINDS WITH A FEW CELLS EXHIBITING BOWING STRUCTURES NOTED ACROSS NERN LA. MID-LEVEL LAPSE RATES OVER 7 DEG C/KM AND 0-6KM BULK SHEAR AROUND 50 KT INDICATE ISOLATED SEVERE HAIL CANNOT BE RULED OUT. HOWEVER...THIS THREAT APPEARS TO BE A SECONDARY GIVEN THE WANING INSTABILITY RESULTANT FROM BOUNDARY LAYER COOLING. IN ADDITION...LOW-LEVEL SHEAR /0-1 KM SRH AROUND 150-200 PER SHV AND LCH 00Z SOUNDINGS/ INDICATES THE TORNADO THREAT IS NON-ZERO BUT THE GRADUALLY DECOUPLING BOUNDARY LAYER SHOULD KEEP THE THREAT VERY LOW AND TRANSIENT. ..MOSIER.. 12/10/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MEG...JAN...LZK...LCH...SHV...HGX...FWD... LAT...LON 30269643 34059350 34029039 30269342 30269643
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 9, 8:02 PM CST | Mesoscale Discussion | SPC | Arkansas, Crittenden, Cross, Lee, Mississippi, Monroe and 3 more | 58 min |
| Dec 9, 9:59 PM CST | Mesoscale Discussion | SPC | Concordia, East Carroll, Franklin, Madison, Tensas | 61 min |
| Dec 9, 11:24 PM CST | Mesoscale Discussion | SPC | Caldwell, Catahoula, East Carroll, Franklin, Grant, LaSalle and 6 more | 66 min |
| Dec 10, 4:07 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 23 more | 113 min |
| Dec 10, 5:44 AM CST | Tornado Watch | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 10 more | 5 hr |
| Dec 10, 7:31 AM CST | Mesoscale Discussion | SPC | Ascension, Assumption, Iberia, Jefferson, Lafourche, Livingston and 11 more | 119 min |
| Dec 10, 8:51 AM CST | Tornado Watch | SPC | Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint John the Baptist and 1 more | 6 hr |
| Dec 10, 10:24 AM CST | Mesoscale Discussion | SPC | Orleans | 2 hr |
Nearby
Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Arkansas, 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.