Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 1828
The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2012, 3:46 PM CDT for 4 states. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Aug 28, 2012, 3:46 PM CDT (20:46 UTC)
- Expired
- Aug 28, 2012, 5:15 PM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
All 38 counties
Baldwin County, AL, Clarke County, AL, Escambia County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Jefferson Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS
The radar
The Mobile radar (KMOB), 106 km from the middle of the area, began a volume at 20:47 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
Slidell Radar S, LA (KSIL), launched 12:00Z, 8.8 hours before the alert went out and 47 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
- 41 J/kg
- Mixed-layer CIN
- -110 J/kg
- Mixed-layer LCL
- 650 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 272 m²/s²
- 0-3 km storm-relative helicity
- 266 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
255
ACUS11 KWNS 282046
SWOMCD
SPC MCD 282046
FLZ000-ALZ000-MSZ000-LAZ000-282215-
MESOSCALE DISCUSSION 1828
NWS STORM PREDICTION CENTER NORMAN OK
0346 PM CDT TUE AUG 28 2012
AREAS AFFECTED...PORTIONS OF SRN MS / SERN LA / SWRN AL / WRN FL
PNHDL
CONCERNING...TORNADO WATCH 591...592...
VALID 282046Z - 282215Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 591...592...CONTINUES.
SUMMARY...THE THREAT FOR TORNADOES CONTINUES WITH ANY
SUSTAINED...ROTATING STORMS EMBEDDED WITHIN LARGER-SCALE RAINBANDS.
DISCUSSION...20Z SURFACE/BUOY OBSERVATIONS AND RECENT RADAR DATA
INDICATE THE CENTER OF HURRICANE ISAAC JUST OFFSHORE...TO THE SE OF
BVE. AN ASSOCIATED OUTER RAINBAND WHICH DEVELOPED EARLIER TODAY
FROM NEAR MOB-S OF CEW HAS SINCE PIVOTED NWWD...AND AS OF
2020Z...EXTENDED FROM MCB-SE MEI. BASED ON 18Z JAN AND LIX
SOUNDINGS...THIS CONVECTION WHICH HAS EXHIBITED PERSISTENT
LIGHTNING...IS OCCURRING WITHIN A WEAK LAPSE RATE ENVIRONMENT WITH
SBCAPE VALUES OF 800-1500 J/KG. MOREOVER...INTERPOLATION OF JAN AND
MOB VAD DATA INDICATES THAT THIS ACTIVITY IS GRADUALLY BECOMING
DISPLACED FROM THE STRONGER LOW TO MID-TROPOSPHERIC WIND FIELD
ATTENDANT TO ISAAC.
AN ADDITIONAL...OUTER RAINBAND HAS MORE RECENTLY FORMED ALONG ERN
EDGE OF CDO FROM MOBILE BAY SSEWD INTO THE GULF OF MEXICO. BASED ON
OBSERVATIONS AND MODEL-DERIVED PARAMETER FIELDS...THIS ACTIVITY
APPEARS TO COINCIDE WITH A STRONGLY SHEARED ENVIRONMENT...AND AT
LEAST MODEST INSTABILITY. AS SUCH...A COMPARATIVELY GREATER RISK
FOR SUPERCELLS AND TORNADOES WILL EXIST LATE THIS AFTERNOON FROM
SWRN AL INTO SERN MS.
..MEAD.. 08/28/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MOB...JAN...LIX...
LAT...LON 28988987 28889064 29269122 29729090 29929060 30329048
31219045 31529027 31738942 31898805 31698734 30838659
30278654 30138729 30068837 29528875 29108908 28988987SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 28, 7:01 AM CDT | Mesoscale Discussion | SPC | Baldwin, Clarke, Coffee, Conecuh, Covington, Escambia and 4 more | 2 hr |
| Aug 28, 9:46 AM CDT | Tornado Watch | SPC | Baldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more | 9 hr |
| Aug 28, 12:37 PM CDT | Mesoscale Discussion | SPC | Baldwin, Escambia, Mobile, Washington | 83 min |
| Aug 28, 5:48 PM CDT | Mesoscale Discussion | SPC | Baldwin, Conecuh, Covington, Escambia, Mobile, Monroe and 1 more | 87 min |
| Aug 28, 6:47 PM CDT | Tornado Watch | SPC | Baldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more | 21 hr |
| Aug 28, 12:56 PM CDT | Tornado Watch | SPC | Covington, Forrest, Jefferson Davis, Jones, Lamar, Lawrence and 2 more | 6 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; radar from the NEXRAD Level II archive.