Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 995
The Storm Prediction Center issued this mesoscale discussion at May 31, 2012, 11:59 AM CDT for 4 states. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- May 31, 2012, 11:59 AM CDT (16:59 UTC)
- Expired
- May 31, 2012, 1:00 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 64 counties
Arkansas County, AR, Ashley County, AR, Chicot County, AR, Crittenden County, AR, Cross County, AR, Desha County, AR, Drew County, AR, Lee County, AR, Mississippi County, AR, Monroe County, AR, Phillips County, AR, St. Francis County, AR, Dunklin County, MO, Pemiscot County, MO, Alcorn County, MS, Attala County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Lafayette County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Marshall County, MS, Montgomery County, MS, Neshoba County, MS, Panola County, MS, Pontotoc County, MS, Quitman County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Washington County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS, Chester County, TN, Crockett County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Shelby County, TN, Tipton 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, 5.0 hours before the alert went out and 111 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.
700
ACUS11 KWNS 311700
SWOMCD
SPC MCD 311659
TNZ000-MSZ000-MOZ000-ARZ000-311800-
MESOSCALE DISCUSSION 0995
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT THU MAY 31 2012
AREAS AFFECTED...SERN AR...NRN MS...WRN TN...BOOTHEEL OF MO
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 311659Z - 311800Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...STORM COVERAGE IS EXPECTED TO INCREASE THIS AFTERNOON
ACROSS SERN AR AND NRN MS...WITH DMGG WINDS AND HAIL LIKELY AS
CONVECTION BECOMES BETTER ORGANIZED.
DISCUSSION...A LINGERING MCV FROM EARLIER CONVECTION NOTED S OF
LITTLE ROCK WILL CONTINUE TO DRIFT EWD...GRADUALLY INITIATING NEW
CONVECTION EARLY THIS AFTERNOON. ALTHOUGH THE APPEARANCE ON VISIBLE
IMAGERY IS INDICATIVE OF STABILITY...THE MCV IS APPROACHING AN AREA
THAT REMAINS MOIST AND HAS BEEN DESTABILIZING AMIDST AMPLE SURFACE
HEATING. ADDITIONAL REINFORCEMENT FOR CONVECTIVE DEVELOPMENT WILL BE
POSSIBLE AS A COLD FRONT OVER ERN AR CONTINUES EWD COINCIDENT WITH
THE MCV.
FARTHER S...SEVERE THUNDERSTORMS HAVE DEVELOPED ALONG AN AREA OF
SURFACE CONVERGENCE...WITHIN THE MOIST/UNSTABLE SECTOR. THESE STORMS
MAY APPROACH THE EDGE OF WW327 SHORTLY...AND A NEW WW IS BEING
CONSIDERED DOWNSTREAM. THE 12Z JAN SOUNDING INDICATES MINIMAL
CONVECTIVE INHIBITION...WITH STEEPING LOW-MID LEVEL LAPSE RATES
BECOMING SUPPORTIVE OF ROBUST UPDRAFTS. DEEP-LAYER WINDS WILL BEGIN
TO STRENGTHEN THROUGHOUT THE AFTERNOON IN ADVANCE OF AN APPROACHING
UPPER TROUGH...POSSIBLY LEADING TO A MORE ORGANIZED THREAT WITH
TIME.
..HURLBUT/WEISS.. 05/31/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MEG...JAN...LZK...
LAT...LON 33109210 34749135 36159018 36378905 36098851 35308842
34278871 33568889 32078927 32029016 32139057 32679069
32999093 33059119 33109210SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| 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, 12:59 PM CDT | Severe Thunderstorm Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Lee and 4 more | 6 hr |
| May 31, 2:38 PM CDT | Mesoscale Discussion | SPC | Crittenden, Phillips | 67 min |
| 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, 5:30 PM CDT | Mesoscale Discussion | SPC | Prentiss, Tishomingo | 2 hr |
| May 31, 1:56 PM CDT | Mesoscale Discussion | SPC | Dunklin, Mississippi, New Madrid, Pemiscot | 64 min |
| May 31, 2:34 PM CDT | Severe Thunderstorm Watch | SPC | Mississippi, New Madrid | 6 hr |
| May 31, 6:00 PM CDT | Severe Thunderstorm Watch | SPC | Bedford, Benton, Cheatham, Clay, Davidson, Dickson and 23 more | 4 hr |
Nearby
Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Tennessee, 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.