Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 998
The Storm Prediction Center issued this mesoscale discussion at May 31, 2012, 2:38 PM CDT for 4 states. It was in force for 67 min.
The area
The outline as issued.
The facts
- Issued
- May 31, 2012, 2:38 PM CDT (19:38 UTC)
- Expired
- May 31, 2012, 3:45 PM CDT
- In force
- 67 min
- Issued by
- the Storm Prediction Center
All 62 counties
Lamar County, AL, Crittenden County, AR, Phillips County, AR, Alcorn County, MS, Attala County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Itawamba County, MS, Lafayette County, MS, Leake County, MS, Lee County, MS, Leflore County, MS, Lowndes County, MS, Madison County, MS, Marshall County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Noxubee County, MS, Oktibbeha County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Tunica County, MS, Union County, MS, Washington County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS, Carroll County, TN, Chester County, TN, Crockett County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Henderson County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Little Rock, AR (KLZK), launched 12:00Z, 7.6 hours before the alert went out and 78 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
- 1245 J/kg
- Mixed-layer CIN
- -112 J/kg
- Mixed-layer LCL
- 776 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 122 m²/s²
- 0-3 km storm-relative helicity
- 139 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
425
ACUS11 KWNS 311939
SWOMCD
SPC MCD 311938
ALZ000-TNZ000-MSZ000-MOZ000-ARZ000-LAZ000-312045-
MESOSCALE DISCUSSION 0998
NWS STORM PREDICTION CENTER NORMAN OK
0238 PM CDT THU MAY 31 2012
AREAS AFFECTED...WRN TN...NRN MS
CONCERNING...SEVERE THUNDERSTORM WATCH 328...
VALID 311938Z - 312045Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 328
CONTINUES.
SUMMARY...SEVERE THUNDERSTORMS CAPABLE OF DMGG WINDS AND HAIL WILL
CONTINUE EWD...WITH THE LEADING EDGE OF THE COMPLEX APPROACHING THE
EDGE OF THE WW BY 2030Z. ADDITIONAL COUNTIES MAY BE NEEDED FOR WW328
IN NERN MS.
DISCUSSION...ORGANIZED THUNDERSTORMS HAVE DEVELOPED AHEAD OF AN MCV
FEATURE OVER NWRN MS...AND IN RESPONSE TO FORCING FOR ASCENT AHEAD
OF A WEAK UPPER TROUGH. STEEP LOW LEVEL LAPSE RATES /8-8.5 C/KM PER
MESOANALYSIS/ IN ADVANCE OF THE COMPLEX MAY MAINTAIN A DMGG WIND
THREAT...WITH STRENGTHENING DEEP LAYER SHEAR SUPPORTING A HAIL
THREAT WITH THE STRONGER CORES. A LOCAL EXTENSION IN AREA MAY BE
NEEDED FOR PORTIONS OF NERN MS. FARTHER E INTO AL...THE AIR MASS IS
LESS STABLE OWING TO A RAIN COOLED AIR MASS FROM EARLIER CONVECTION.
WITH CLOUD COVER BEGINNING TO SHIFT EWD...SUFFICIENT DESTABILIZATION
MAY BE ABLE TO OCCUR BEFORE THE THUNDERSTORM COMPLEX TRAVERSES INTO
AL. HOWEVER...A REMNANT MOISTURE GRADIENT FROM YESTERDAY STILL
EXISTS...WITH RELATIVELY LOWER DEW POINT VALUES INTO CNTRL/NRN AL.
AS SUCH...A WEAKENING TREND IN THE ONGOING CONVECTION IS POSSIBLE AS
IT PROGRESSES INTO AL LATER THIS AFTERNOON.
..HURLBUT.. 05/31/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BMX...HUN...MEG...JAN...LZK...
LAT...LON 35248835 34238799 33018822 32628904 32459021 32729093
33139122 34399088 35489029 36308956 36358834 35248835SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 31, 5:21 PM CDT | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more | 84 min |
| May 31, 5:30 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lauderdale, Lawrence, Limestone | 2 hr |
| May 31, 6:00 PM CDT | Severe Thunderstorm Watch | SPC | Colbert, Franklin, Lauderdale, Lawrence, Limestone, Madison and 1 more | 4 hr |
| May 30, 7:32 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more | 8 hr |
| May 30, 11:21 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Madison, Washington | 114 min |
| May 31, 1:52 AM CDT | Mesoscale Discussion | SPC | Benton, Crawford, Washington | 83 min |
| May 31, 11:59 AM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Chicot, Crittenden, Cross, Desha and 6 more | 61 min |
| May 31, 12:59 PM CDT | Severe Thunderstorm Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Lee and 4 more | 6 hr |
| May 31, 10:41 AM CDT | Severe Thunderstorm Watch | SPC | Adams, Amite, Claiborne, Copiah, Franklin, Issaquena and 5 more | 6 hr |
| May 31, 1:53 PM CDT | Mesoscale Discussion | SPC | Adams, Amite, Attala, Choctaw, Claiborne, Clarke and 36 more | 67 min |
| May 31, 2:53 PM CDT | Severe Thunderstorm Watch | SPC | Clarke, Covington, Forrest, George, Greene, Hancock and 18 more | 5 hr |
| May 31, 1:56 PM CDT | Mesoscale Discussion | SPC | Lake | 64 min |
Nearby
Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Tennessee, 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.