Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 184

February 29, 20125 states

The Storm Prediction Center issued this mesoscale discussion at Feb 29, 2012, 11:46 AM CST for 5 states. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
Feb 29, 2012, 11:46 AM CST (17:46 UTC)
Expired
Feb 29, 2012, 1:15 PM CST
In force
89 min
Issued by
the Storm Prediction Center
All 76 counties

Colbert County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Marion County, AL, Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Desha County, AR, Drew County, AR, Lee County, AR, Lincoln County, AR, Monroe County, AR, Phillips County, AR, Union County, AR, Bienville Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, East Carroll Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn 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, DeSoto 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, 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, Tunica County, MS, Union County, MS, Washington County, MS, Webster County, MS, Yalobusha County, MS, Yazoo County, MS, Fayette County, TN, Hardeman County, TN, Hardin County, TN, McNairy County, TN

The radar

The Columbus AFB radar (KGWX), 159 km from the middle of the area, began a volume at 17:47 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

Little Rock, AR (KLZK), launched 12:00Z, 5.8 hours before the alert went out and 104 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.

Skew-T log-pSkew-T log-p diagram, Little Rock, AR at 12:00Z on 2012-02-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1168 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Little Rock, AR at 12:00Z on 2012-02-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 289 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1168 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
535 m above ground
0-6 km bulk shear
64 kt
0-1 km storm-relative helicity
289 m²/s²
0-3 km storm-relative helicity
292 m²/s²
Significant tornado parameter
2.3
Supercell composite
8.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

511 
ACUS11 KWNS 291746
SWOMCD
SPC MCD 291746 
ALZ000-TNZ000-MSZ000-ARZ000-LAZ000-291915-

MESOSCALE DISCUSSION 0184
NWS STORM PREDICTION CENTER NORMAN OK
1146 AM CST WED FEB 29 2012

AREAS AFFECTED...SERN AR...NRN LA...NRN MS...NWRN AL

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 291746Z - 291915Z

STORMS ARE EXPECTED TO EVENTUALLY DEVELOP ALONG THE COLD FRONT AND
SWEEP EWD WITH WIDESPREAD DAMAGING WINDS AND A FEW TORNADOES. A
WATCH IS LIKELY TO BE ISSUED BY 19-20Z.

SURFACE ANALYSIS SHOWS THE COLD FRONT JUST W OF SHREVEPORT LA INTO
NERN AR AT 17Z. ALTHOUGH EXTENSIVE LOW CLOUDS EXIST OVER MUCH OF THE
AREA...THERE ARE POCKETS OF HEATING ESPECIALLY OVER CNTRL LA INTO
CNTRL MS. GRADUAL DESTABILIZATION AND LIFT ALONG THE FRONT SHOULD
RESULT IN A LINE OF SEVERE THUNDERSTORMS THIS AFTERNOON.

AMPLE DEEP LAYER FLOW EXISTS FOR FAST STORM MOTIONS AND SEVERE
WINDS...BUT LOW LEVEL FLOW IMMEDIATELY NEAR THE FRONT WILL BE
VEERED...WHICH MAY LIMIT TORNADO POTENTIAL SOMEWHAT...ESPECIALLY IF
MODE IS LINEAR. HOWEVER...BETTER LOW LEVEL SHEAR/BACKED FLOW WILL
REMAIN OVER ERN MS INTO NRN AL.

OBJECTIVE ANALYSIS AND AREA SOUNDINGS SHOW A PRONOUNCED CAPPING
INVERSION NEAR 700 MB...WHICH WILL LIMIT WARM SECTOR DEVELOPMENT
AWAY FROM THE FRONT.  HOWEVER...NRN PORTIONS OF THE AREA...FROM NRN
MS INTO NRN AL WILL HAVE THE HIGHEST RELATIVE THREAT OF THIS TYPE OF
DEVELOPMENT. IF THIS SHOULD OCCUR...THE TORNADO THREAT WOULD BE MORE
SUBSTANTIAL.

..JEWELL.. 02/29/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...OHX...BMX...HUN...MEG...JAN...LZK...SHV...

LAT...LON   35278820 35178776 34848728 34528714 34238737 33918778
            33058941 32469101 31999227 31819314 31999353 32539361
            33429289 34319184 34899093 35198975 35298878 35278820

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 29, 1:48 PM CSTTornado WatchSPCBlount, Cherokee, Colbert, Cullman, DeKalb, Etowah and 15 more7 hr
Feb 28, 10:30 PM CSTTornado WatchSPCBaxter, Benton, Boone, Carroll, Conway, Crawford and 20 more6 hr
Feb 28, 11:40 PM CSTMesoscale DiscussionSPCBenton95 min
Feb 29, 12:49 AM CSTMesoscale DiscussionSPCArkansas, Bradley, Calhoun, Chicot, Clay, Cleburne and 31 more56 min
Feb 29, 3:20 AM CSTTornado WatchSPCBaxter, Clay, Cleburne, Conway, Craighead, Fulton and 20 more9 hr
Feb 29, 3:53 AM CSTMesoscale DiscussionSPCBaxter, Clay, Cleburne, Conway, Craighead, Faulkner and 20 more97 min
Feb 29, 8:07 AM CSTMesoscale DiscussionSPCClay, Craighead, Greene, Independence, Jackson, Lawrence and 2 more53 min
Feb 29, 11:11 AM CSTMesoscale DiscussionSPCCrittenden, Mississippi2 hr
Feb 29, 2:15 PM CSTSevere Thunderstorm WatchSPCAshley, Chicot6 hr
Feb 29, 3:34 PM CSTMesoscale DiscussionSPCAlcorn, Benton, Marshall116 min
Feb 29, 2:40 AM CSTMesoscale DiscussionSPCCheatham, Clay, Davidson, Dickson, Hickman, Houston and 11 more65 min
Feb 29, 4:39 AM CSTTornado WatchSPCBenton, Cheatham, Clay, Davidson, Dickson, Fentress and 14 more7 hr
Feb 29, 7:38 AM CSTMesoscale DiscussionSPCBenton, Cheatham, Clay, Davidson, DeKalb, Dickson and 15 more67 min
Feb 29, 11:31 AM CSTTornado WatchSPCAnderson, Bedford, Benton, Bledsoe, Campbell, Cannon and 68 more8 hr
Feb 29, 2:23 PM CSTMesoscale DiscussionSPCJohnson67 min
Feb 29, 4:36 PM CSTMesoscale DiscussionSPCBlount, Bradley, Carter, Cocke, Greene, Hamilton and 6 more54 min
Feb 29, 5:37 PM CSTTornado WatchSPCBlount, Bradley, Carter, Cocke, Greene, Hamilton and 10 more3 hr

Nearby

Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Louisiana, 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; radar from the NEXRAD Level II archive.