Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 320
The Storm Prediction Center issued this mesoscale discussion at Mar 21, 2012, 3:47 PM CDT for 4 counties in Alabama; Saint Bernard Parish, Louisiana; 18 counties in Mississippi. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Mar 21, 2012, 3:47 PM CDT (20:47 UTC)
- Expired
- Mar 21, 2012, 5:15 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
All 23 counties
Choctaw County, AL, Mobile County, AL, Sumter County, AL, Washington County, AL, Saint Bernard Parish, LA, Clarke County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jones County, MS, Kemper County, MS, Lauderdale County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Perry County, MS, Stone County, MS, Wayne County, MS, Winston County, MS
The radar
The Mobile radar (KMOB), 116 km from the middle of the area, began a volume at 20:48 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Jackson, MS (KJAN), launched 12:00Z, 8.8 hours before the alert went out and 151 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
- 143 J/kg
- Mixed-layer CIN
- -17 J/kg
- Mixed-layer LCL
- 559 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 239 m²/s²
- 0-3 km storm-relative helicity
- 239 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.8
The text
As transmitted, in the capitals the NWS used until 2016.
908
ACUS11 KWNS 212048
SWOMCD
SPC MCD 212047
ALZ000-MSZ000-LAZ000-212215-
MESOSCALE DISCUSSION 0320
NWS STORM PREDICTION CENTER NORMAN OK
0347 PM CDT WED MAR 21 2012
AREAS AFFECTED...COASTAL SOUTHEAST LA AND SOUTHEAST/EAST-CENTRAL MS
TO EXTREME WESTERN AL
CONCERNING...TORNADO WATCH 97...
VALID 212047Z - 212215Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 97 CONTINUES.
TORNADO WATCH 97 CONTINUES UNTIL 23Z FOR COASTAL SOUTHEAST LA AND
PORTIONS OF SOUTHEAST/EAST-CENTRAL MS...WITH POTENTIAL FOR DAMAGING
WINDS AND A FEW TORNADOES. EARLY THINKING IS THAT A TEMPORAL WATCH
EXTENSION COULD BE NEEDED FOR A SMALL PART OF WW 97 PRIOR TO 23Z.
FARTHER EAST...A SEVERE THREAT CANNOT BE RULED OUT INTO FAR WESTERN
AL OVER THE NEXT FEW HOURS...BUT AN ADDITIONAL WATCH IS NOT
CURRENTLY EXPECTED.
QUASI-LINEAR CONVECTIVE SYSTEM CONTINUES TO MAKE A SLOW
EAST-NORTHEASTWARD PROGRESSION ACROSS COASTAL SOUTHEAST LA AND
SOUTHEAST/EAST-CENTRAL MS THIS AFTERNOON /ROUGHLY PARALLEL TO I-59
AS OF 2030Z/...WHILE FASTER-MOVING INDIVIDUAL CONVECTIVE ELEMENTS
RACE NORTH-NORTHEASTWARD. EMBEDDED SUPERCELLS AND BOWS...INCLUDING
COMMA-HEAD TYPE VORTICES...HAVE BEEN NOTED WITHIN THE QLCS AS STRONG
WIND PROFILES CONTINUE TO BE SAMPLED BY REGIONAL WSR-88D VWPS. WHILE
A TORNADO/WIND DAMAGE THREAT WILL PERSIST...THE QLCS WILL BEGIN TO
ENCOUNTER A MORE STABLE AIRMASS WITH EASTWARD EXTENT INTO WESTERN AL
AS IT MOVES OUT OF THE PRIMARY INSTABILITY AXIS...SUCH THAT AN
ADDITIONAL WATCH CURRENTLY SEEMS UNLIKELY TO THE EAST OF TORNADO
WATCH 97. THAT SAID...EXISTING QLCS ORGANIZATION/MOMENTUM MAY
CONTINUE AN ISOLATED SEVERE THREAT INTO AT LEAST PORTIONS OF FAR
WESTERN AL...WHERE THE AIRMASS HAS MOISTENED/DESTABILIZED THIS
AFTERNOON.
..GUYER.. 03/21/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BMX...MOB...JAN...LIX...
LAT...LON 32528915 33108912 33248829 32688817 32088810 31558801
31068789 30228805 29978884 29358952 30958956 32198914
32528915SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 20, 8:02 PM CDT | Tornado Watch | SPC | Beauregard, Calcasieu, Cameron, Vernon | 4 hr |
| Mar 20, 10:23 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Jefferson Davis, Natchitoches, Vernon | 67 min |
| Mar 20, 10:59 PM CDT | Tornado Watch | SPC | Acadia, Allen, Beauregard, Bienville, Calcasieu, Caldwell and 17 more | 7 hr |
| Mar 21, 2:17 AM CDT | Mesoscale Discussion | SPC | Acadia, Avoyelles, Caldwell, Catahoula, Concordia, Evangeline and 17 more | 118 min |
| Mar 21, 4:38 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Avoyelles, Catahoula, Concordia, East Baton Rouge and 19 more | 97 min |
| Mar 21, 5:04 AM CDT | Tornado Watch | SPC | Acadia, Ascension, Assumption, Avoyelles, Caldwell, Catahoula and 33 more | 7 hr |
| Mar 21, 7:48 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Avoyelles, East Baton Rouge, East Feliciana, Iberville and 10 more | 87 min |
| Mar 21, 9:25 AM CDT | Mesoscale Discussion | SPC | Ascension, Concordia, East Baton Rouge, East Carroll, East Feliciana, Franklin and 17 more | 95 min |
| Mar 21, 10:07 AM CDT | Tornado Watch | SPC | Ascension, East Carroll, East Feliciana, Franklin, Jefferson, Lafourche and 17 more | 8 hr |
| Mar 21, 12:19 PM CDT | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Tammany and 1 more | 86 min |
| Mar 21, 5:40 PM CDT | Mesoscale Discussion | SPC | Orleans, Plaquemines, Saint Bernard | 35 min |
| Mar 21, 6:02 PM CDT | Tornado Watch | SPC | Plaquemines, Saint Bernard | 9 hr |
Nearby
Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Louisiana, 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.