Alert archive / Mississippi / Mesoscale Discussions in 2011

Mesoscale Discussion 435

April 15, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2011, 4:21 AM CDT for 4 states. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued
Apr 15, 2011, 4:21 AM CDT (09:21 UTC)
Expired
Apr 15, 2011, 5:45 AM CDT
In force
84 min
Issued by
the Storm Prediction Center
All 96 counties

Colbert County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Marion County, AL, Pickens County, AL, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Richland Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Alcorn County, MS, Attala County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Clay County, MS, Copiah County, MS, DeSoto County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Itawamba County, MS, Jefferson County, MS, Kemper 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, Rankin County, MS, Scott 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, Winston County, MS, Yalobusha County, MS, Yazoo County, MS, Benton County, TN, Carroll County, TN, Cheatham County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dickson County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, Madison County, TN, McNairy County, TN, Perry County, TN, Stewart County, TN, Wayne County, TN, Weakley County, TN

The radar

The Jackson/Brandon,MS radar (KDGX), 149 km from the middle of the area, began a volume at 09:23 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 00:00Z, 9.4 hours before the alert went out and 136 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 00:00Z on 2011-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 195 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 00:00Z on 2011-04-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939587897Sfc1 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
195 J/kg
Mixed-layer CIN
-128 J/kg
Mixed-layer LCL
1615 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
170 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

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

717 
ACUS11 KWNS 150922
SWOMCD
SPC MCD 150921
TNZ000-ALZ000-KYZ000-MSZ000-LAZ000-ARZ000-151045-

MESOSCALE DISCUSSION 0435
NWS STORM PREDICTION CENTER NORMAN OK
0421 AM CDT FRI APR 15 2011

AREAS AFFECTED...NRN LA...SERN AR...CNTRL AND NRN MS...WRN/MIDDLE TN

CONCERNING...TORNADO WATCH 139...

VALID 150921Z - 151045Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 139 CONTINUES.

A NEW WW MAY BECOME NECESSARY EAST OF WW 139 WITHIN THE NEXT HOUR OR
TWO.

INFLOW INTO ONGOING STRONG/SEVERE MESOSCALE CONVECTIVE SYSTEM IS
STRONGEST ON IT SOUTHERN FLANK...NOW SPREADING ACROSS SOUTHERN
ARKANSAS AND NORTHERN LOUISIANA...WHERE BOUNDARY LAYER MOISTURE
CHARACTERIZED BY MID/UPPER 60S SURFACE DEW POINTS CONTINUES TO
SUPPORT MODERATE CAPE AROUND 1000-1500 J/KG.  IN THE PRESENCE OF A
SHEARED AND STRONG DEEP LAYER MEAN FLOW FIELD...ON THE ORDER OF
40-50+ KT...THIS SEEMS LIKELY TO MAINTAIN THE STRENGTH OF THE
CONVECTION THROUGH AND BEYOND DAYBREAK...EVEN AS STRONGEST MID/UPPER
SUPPORT DEVELOPS NORTHEAST OF THE REGION TOWARD THE LOWER OHIO
VALLEY.  AS A RESULT THE RISK FOR DAMAGING WIND GUSTS ...PERHAPS
ISOLATED TORNADOES...SHOULD CONTINUE EASTWARD ACROSS MUCH OF CENTRAL
MISSISSIPPI THROUGH THE 10-12Z TIME FRAME.

FARTHER NORTH...THE INTENSITY OF THE SQUALL LINE HAS RECENTLY
DIMINISHED AS IT APPROACHED THE MISSISSIPPI RIVER...BUT BOUNDARY
LAYER MOISTENING IN A NARROW CORRIDOR AHEAD OF THE ACTIVITY STILL
MAY PROVIDE POTENTIAL FOR INTENSIFICATION ACROSS PARTS OF WESTERN
INTO MIDDLE TENNESSEE THROUGH DAYBREAK.

..KERR.. 04/15/2011

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

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

LAT...LON   32959143 33959087 34529026 35308970 36068952 36538803
            36238697 33038806 32478907 31739018 31439129 31549255
            31949282 32959143

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 15, 7:32 AM CDTTornado WatchSPCBlount, Choctaw, Clarke, Colbert, Cullman, Fayette and 20 more7 hr
Apr 15, 10:28 AM CDTMesoscale DiscussionSPCAutauga, Baldwin, Bibb, Blount, Butler, Chilton and 34 more2 hr
Apr 15, 11:21 AM CDTTornado WatchSPCAutauga, Baldwin, Barbour, Bibb, Blount, Bullock and 44 more9 hr
Apr 15, 1:30 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Bullock, Butler, Calhoun and 46 more2 hr
Apr 15, 3:35 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Bullock, Butler, Chambers and 39 more85 min
Apr 15, 5:57 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Lawrence, Marion2 hr
Apr 14, 11:24 PM CDTSevere Thunderstorm WatchSPCBossier, Caddo, Claiborne, De Soto, Webster3 hr
Apr 14, 11:56 PM CDTMesoscale DiscussionSPCBossier, Caddo, De Soto, Webster94 min
Apr 15, 1:27 AM CDTMesoscale DiscussionSPCBienville, Bossier, Claiborne, East Carroll, Jackson, Lincoln and 5 more93 min
Apr 15, 2:19 AM CDTTornado WatchSPCBienville, Bossier, Caddo, Caldwell, Catahoula, Claiborne and 20 more8 hr
Apr 15, 2:41 PM CDTTornado WatchSPCAcadia, Ascension, Assumption, Avoyelles, Concordia, East Baton Rouge and 19 more7 hr
Apr 15, 6:09 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 12 more96 min
Apr 15, 12:29 PM CDTMesoscale DiscussionSPCAlcorn, Benton, DeSoto, Lafayette, Marshall, Panola and 4 more61 min
Apr 15, 2:09 PM CDTTornado WatchSPCAlcorn, Benton, Calhoun, Chickasaw, DeSoto, Itawamba and 13 more7 hr
Apr 15, 3:32 PM CDTMesoscale DiscussionSPCLake, Obion58 min

Nearby

Mesoscale Discussions in Mississippi, 2011Mesoscale Discussions in Tennessee, 2011Mesoscale Discussions in Louisiana, 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.