Alert archive / Mississippi / Mesoscale Discussions in 2011
Mesoscale Discussion 775
The Storm Prediction Center issued this mesoscale discussion at May 13, 2011, 2:44 PM CDT for 5 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 13, 2011, 2:44 PM CDT (19:44 UTC)
- Expired
- May 13, 2011, 4:45 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 47 counties
Crittenden County, AR, Mississippi County, AR, Ballard County, KY, Carlisle County, KY, Fulton County, KY, Graves County, KY, Hickman County, KY, Dunklin County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Scott County, MO, Alcorn County, MS, Benton County, MS, Calhoun County, MS, Chickasaw County, MS, DeSoto County, MS, Grenada County, MS, Lafayette County, MS, Leflore County, MS, Marshall County, MS, Montgomery County, MS, Panola County, MS, Pontotoc County, MS, Quitman County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Webster County, MS, Yalobusha County, MS, Chester County, TN, Crockett County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN
The radar
The Memphis radar (KNQA), 25 km from the middle of the area, began a volume at 19:44 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
Little Rock, AR (KLZK), launched 12:00Z, 7.7 hours before the alert went out and 55 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
- 1232 J/kg
- Mixed-layer CIN
- -20 J/kg
- Mixed-layer LCL
- 494 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 105 m²/s²
- 0-3 km storm-relative helicity
- 154 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 3.1
The text
As transmitted, in the capitals the NWS used until 2016.
113
ACUS11 KWNS 131945
SWOMCD
SPC MCD 131944
TNZ000-MSZ000-KYZ000-ILZ000-MOZ000-ARZ000-132145-
MESOSCALE DISCUSSION 0775
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT FRI MAY 13 2011
AREAS AFFECTED...NERN AR...SERN MO...SWRN KY...EXTREME SRN IL...WRN
TN AND NRN MS
CONCERNING...SEVERE THUNDERSTORM WATCH 298...
VALID 131944Z - 132145Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 298
CONTINUES.
THREAT FOR ISOLATED LARGE HAIL AND DAMAGING WIND WILL PERSIST NEXT
FEW HOURS AS STORMS DEVELOP AND MOVE THROUGH THE LOWER MS VALLEY AND
WRN PORTION OF THE TN VALLEY.
AN EXPANSIVE OUTFLOW BOUNDARY EXTENDS FROM THE SERN STATES NWWD
THROUGH NWRN MS...INTO EXTREME ERN AR. A COLD FRONT STRETCHES FROM
THE MIDDLE MS VALLEY SWD THROUGH ERN AR WHERE IT MERGES WITH THE
OUTFLOW BOUNDARY THEN CONTINUES SWWD INTO TX. STORMS ARE DEVELOPING
PRIMARILY WITHIN ZONE OF LOW LEVEL CONVERGENCE ALONG THE OUTFLOW
BOUNDARY FROM NRN MS INTO ERN AR...WRN TN AND SERN MO. THE CAP HAS
BEEN WEAKENED IN THIS REGION BY DIABATIC WARMING AND DEEPER ASCENT
ASSOCIATED WITH VORT MAX ROTATING THROUGH UPPER TROUGH BASE. STORMS
REMAIN MOSTLY DISCRETE AND SUPERCELLULAR IN CHARACTER WITH A THREAT
OF MAINLY LARGE HAIL AND ISOLATED DAMAGING WIND. DIABATIC HEATING IS
PROMOTING RECOVERY OVER WRN TN ON THE COOLER SIDE OF OUTFLOW
BOUNDARY...SUGGESTING STORMS WILL CONTINUE TO POSE A THREAT FOR
ISOLATED LARGE HAIL AND DAMAGING WIND AS THEY DEVELOP EWD...WHILE
REMAINING EMBEDDED WITHIN 35-45 KT UNIDIRECTIONAL SHEAR.
..DIAL.. 05/13/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...MEG...JAN...
LAT...LON 34409057 36099008 37098986 37238883 36428849 34698859
33478906 33459058 34409057SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 12, 9:41 PM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Cleburne, Conway, Crawford, Faulkner and 22 more | 64 min |
| May 12, 10:03 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Cleburne, Conway, Crawford, Faulkner, Franklin and 26 more | 7 hr |
| May 12, 10:09 PM CDT | Mesoscale Discussion | SPC | Clay | 66 min |
| May 13, 12:01 PM CDT | Mesoscale Discussion | SPC | Arkansas, Clay, Craighead, Crittenden, Cross, Greene and 13 more | 89 min |
| May 13, 12:31 PM CDT | Severe Thunderstorm Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Lawrence and 6 more | 6 hr |
| May 13, 11:22 AM CDT | Mesoscale Discussion | SPC | Bell, Clay, Harlan, Knox, Leslie, Whitley | 113 min |
| May 13, 2:47 PM CDT | Mesoscale Discussion | SPC | Harlan, Letcher | 58 min |
| May 13, 5:03 PM CDT | Mesoscale Discussion | SPC | Christian, Hopkins, Logan, Muhlenberg, Todd, Trigg | 57 min |
| May 13, 5:54 PM CDT | Severe Thunderstorm Watch | SPC | Allen, Butler, Caldwell, Calloway, Christian, Crittenden and 17 more | 6 hr |
| May 12, 9:16 PM CDT | Mesoscale Discussion | SPC | Atchison | 59 min |
| May 13, 4:40 PM CDT | Mesoscale Discussion | SPC | Lincoln, Saint Charles, Saint Louis, City of Saint Louis | 95 min |
| May 13, 12:10 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Blount, Bradley, Campbell, Carter, Claiborne and 24 more | 6 hr |
Nearby
Mesoscale Discussions in Mississippi, 2011Mesoscale Discussions in Tennessee, 2011Mesoscale Discussions in Kentucky, 2011Every mesoscale discussion in 2011
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.