Alert archive / Mississippi / Mesoscale Discussions in 2017
Mesoscale Discussion 271
The Storm Prediction Center issued this mesoscale discussion at Mar 7, 2017, 8:03 AM CST for 4 states. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Mar 7, 2017, 8:03 AM CST (14:03 UTC)
- Expired
- Mar 7, 2017, 10:00 AM CST
- In force
- 117 min
- Issued by
- the Storm Prediction Center
All 60 counties
Ashley County, AR, Chicot County, AR, Desha County, AR, Drew County, AR, Union County, AR, Bienville Parish, LA, Claiborne Parish, LA, East Carroll Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, 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, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Leflore County, MS, Madison County, MS, Marshall County, MS, Monroe County, MS, Montgomery 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, Union County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Yalobusha County, MS, Yazoo County, MS, Chester County, TN, Fayette County, TN, Hardeman County, TN, McNairy County, TN
The radar
The Jackson/Brandon,MS radar (KDGX), 161 km from the middle of the area, began a volume at 14:02 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 nearest sounding before it
Jackson, MS (KJAN), launched 12:00Z, 2.1 hours before the alert went out and 153 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
- 3 J/kg
- Mixed-layer CIN
- -150 J/kg
- Mixed-layer LCL
- 613 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 374 m²/s²
- 0-3 km storm-relative helicity
- 440 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
947
ACUS11 KWNS 071403
SWOMCD
SPC MCD 071403
ALZ000-TNZ000-MSZ000-ARZ000-LAZ000-071600-
Mesoscale Discussion 0271
NWS Storm Prediction Center Norman OK
0803 AM CST Tue Mar 07 2017
Areas affected...Southwest TN...northern MS...eastern and southern
AR...and northern LA
Concerning...Severe Thunderstorm Watch 69...
Valid 071403Z - 071600Z
The severe weather threat for Severe Thunderstorm Watch 69
continues.
SUMMARY...The potential for locally strong wind gusts persists this
morning across the valid parts of WW 69 from southwest TN through
northern MS, eastern and southern AR, and northern LA.
DISCUSSION...At 1335Z, mosaic radar imagery showed a band of
showers/thunderstorms extending from southwest TN, through extreme
northwest MS to southern AR, and moving to the southeast at 20-25
kt. Additional convection was developing in the marginally to
moderately unstable warm sector, just ahead of the band of
convection from northern LA to northwest MS. This latter
development appears to be aided by low-level warm advection.
Despite extensive multi-layer clouds located south of the
aforementioned band of showers/thunderstorms, an increase in
low-level moisture should sustain MUCAPE of 500-1000 J/kg this
morning. Greater forcing for ascent with the upper trough should
remain north of WW 69 such that frontal ascent and low-level warm
advection will be the primary sources of lift for new thunderstorm
development. The degree of instability and modest low- to mid-level
lapse rates around 6.5 C/km per 12Z SHV sounding suggest stronger
wind gusts will be possible yet this morning, prior to stronger
low-level winds shifting away from the WW 69 region.
..Peters.. 03/07/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MEG...JAN...LZK...SHV...
LAT...LON 32949350 33519200 34389060 35038975 35588900 35558843
34838809 33628823 32878935 32309084 32209141 32169234
32179342 32949350SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 6, 6:02 PM CST | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Crawford, Franklin, Madison and 2 more | 58 min |
| Mar 6, 6:51 PM CST | Tornado Watch | SPC | Benton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more | 8 hr |
| Mar 6, 8:10 PM CST | Mesoscale Discussion | SPC | Baxter, Boone, Carroll, Clay, Cleburne, Conway and 27 more | 3 hr |
| Mar 6, 9:16 PM CST | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Crawford, Franklin, Madison and 3 more | 119 min |
| Mar 6, 9:21 PM CST | Tornado Watch | SPC | Baxter, Boone, Clay, Cleburne, Conway, Craighead and 31 more | 8 hr |
| Mar 7, 2:58 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 47 more | 92 min |
| Mar 7, 3:37 AM CST | Severe Thunderstorm Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 25 more | 8 hr |
| Mar 7, 11:02 AM CST | Mesoscale Discussion | SPC | Avoyelles, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 12 more | 58 min |
| Mar 7, 1:40 PM CST | Mesoscale Discussion | SPC | Clarke, Copiah, Covington, Jasper, Jefferson Davis, Jones and 12 more | 65 min |
Nearby
Mesoscale Discussions in Mississippi, 2017Mesoscale Discussions in Louisiana, 2017Mesoscale Discussions in Arkansas, 2017Every mesoscale discussion in 2017
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.