Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 2148

December 10, 2012Choctaw County, Mobile County, Washington County, Alabama; 17 parishes in Louisiana; 18 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2012, 7:31 AM CST for Choctaw County, Mobile County, Washington County, Alabama; 17 parishes in Louisiana; 18 counties in Mississippi. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued
Dec 10, 2012, 7:31 AM CST (13:31 UTC)
Expired
Dec 10, 2012, 9:30 AM CST
In force
119 min
Issued by
the Storm Prediction Center
All 38 counties

Choctaw County, AL, Mobile County, AL, Washington County, AL, Ascension Parish, LA, Assumption Parish, LA, Iberia Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 1.5 hours before the alert went out and 29 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2012-12-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 767 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2012-12-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 237 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
767 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
488 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
237 m²/s²
0-3 km storm-relative helicity
263 m²/s²
Significant tornado parameter
1.3
Supercell composite
7.9

Open this sounding in Storm Lab

The text

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

713 
ACUS11 KWNS 101332
SWOMCD
SPC MCD 101331
ALZ000-MSZ000-LAZ000-101530-

MESOSCALE DISCUSSION 2148
NWS STORM PREDICTION CENTER NORMAN OK
0731 AM CST MON DEC 10 2012

AREAS AFFECTED...SERN LA...SRN MS...SWRN AL

CONCERNING...TORNADO WATCH 679...

VALID 101331Z - 101530Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 679 CONTINUES.

SUMMARY...THE SEVERE THREAT CONTINUES FOR A FEW BRIEF TORNADOES AND
LOCALLY STRONG WIND GUSTS. THE THREAT MAY PERSIST E OF THE CURRENT
WATCH.

DISCUSSION...A LINE OF THUNDERSTORMS CONTINUES TO MOVE EWD ACROSS
THE REGION. A LEADING LINE JUST AHEAD OF THE COLD FRONT HAS
CONTAINED NUMEROUS COUPLETS OVER THE PAST FEW HOURS. AREA VWPS
CONTINUE TO INDICATE STRONG DEEP LAYER SHEAR AS WELL AS SUFFICIENT
LOW LEVEL SHEAR FOR A MARGINAL TORNADO THREAT. THE AIR MASS ACROSS
SERN LA INTO SRN MS AND AL WILL CONTINUE TO SUPPORT STRONG TO SEVERE
THUNDERSTORMS WITH UPPER 60S F DEWPOINTS.

ONCE THE FRONT MERGES WITH THE LEADING LINE...THE MAIN THREAT SHOULD
WIND.

..JEWELL.. 12/10/2012

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

ATTN...WFO...BMX...MOB...JAN...LIX...LCH...

LAT...LON   29559231 30329130 30649066 31458996 32088931 32218855
            32168813 31858791 31238768 30648780 30198800 28988908
            29059041 28989093 29319155 29559231

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Dec 10, 8:51 AM CSTTornado WatchSPCAutauga, Barbour, Bullock, Chambers, Chilton, Choctaw and 18 more6 hr
Dec 10, 10:24 AM CSTMesoscale DiscussionSPCAutauga, Baldwin, Bullock, Butler, Chambers, Chilton and 22 more2 hr
Dec 10, 12:52 PM CSTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Chambers, Coffee and 18 more113 min
Dec 9, 8:38 PM CSTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 15 more67 min
Dec 9, 9:59 PM CSTMesoscale DiscussionSPCConcordia, East Carroll, Franklin, Madison, Tensas61 min
Dec 9, 11:24 PM CSTMesoscale DiscussionSPCCaldwell, Catahoula, East Carroll, Franklin, Grant, LaSalle and 6 more66 min
Dec 10, 4:07 AM CSTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 23 more113 min
Dec 10, 5:44 AM CSTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 10 more5 hr

Nearby

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