Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 403

March 31, 201212 counties in Alabama; 13 counties in Mississippi; Hardeman County, Tennessee

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2012, 11:33 PM CDT for 12 counties in Alabama; 13 counties in Mississippi; Hardeman County, Tennessee. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Mar 31, 2012, 11:33 PM CDT (04:33 UTC)
Expired: Apr 1, 2012, 12:30 AM CDT
In force: 57 min
Issued by: the Storm Prediction Center

All 26 counties

Autauga County, AL, Bibb County, AL, Dallas County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Lamar County, AL, Lowndes County, AL, Marion County, AL, Perry County, AL, Pickens County, AL, Tuscaloosa County, AL, Alcorn County, MS, Benton County, MS, Chickasaw County, MS, Clay County, MS, Itawamba County, MS, Lee County, MS, Lowndes County, MS, Monroe County, MS, Pontotoc County, MS, Prentiss County, MS, Tippah County, MS, Tishomingo County, MS, Union County, MS, Hardeman County, TN

The radar

The Columbus AFB radar (KGWX), 38 km from the middle of the area, began a volume at 04:36 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

Birmingham, AL (KBMX), launched 00:00Z, 4.6 hours before the alert went out and 127 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 927 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 1532 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

874 
ACUS11 KWNS 010433
SWOMCD
SPC MCD 010433 
ALZ000-MSZ000-TNZ000-010530-

MESOSCALE DISCUSSION 0403
NWS STORM PREDICTION CENTER NORMAN OK
1133 PM CDT SAT MAR 31 2012

AREAS AFFECTED...WEST CENTRAL AND PART OF NWRN AL/NERN MS AND PART
OF SWRN TN

CONCERNING...SEVERE THUNDERSTORM WATCH 123...

VALID 010433Z - 010530Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 123
CONTINUES.

LOCAL WFO AREAL EXTENSION OF WW 123 IS POSSIBLE WWD ACROSS NRN MS AS
STORMS CONTINUE TO BACKBUILD ALONG THE NWRN EDGE OF THE NRN MS/AL
MCS.  THIS SCENARIO IS SUPPORTED BY THE 00Z EXPERIMENTAL WRF-HRRR
WHICH APPEARS TO HAVE THE BEST AGREEMENT WITH REAL-TIME
OBSERVATIONS.

SEVERE WEATHER THREAT /HAIL AND DAMAGING WINDS/ SHOULD REMAIN
CONFINED TO FAR NERN MS/ADJACENT SWRN TN COUNTIES AND INTO PART OF
NWRN-WEST CENTRAL AL PORTION OF WW 123.  IN ADDITION TO THE SEVERE
WEATHER THREAT IN THESE AREAS...BACKBUILDING STORMS ALONG THE NWRN
EXTENT OF THE ATTENDANT MCS IN NERN MS AND ADJACENT PART OF SWRN
TN...WITH ACTIVITY TRACKING SEWD...GIVEN 10-15 KT PROPAGATION
VECTORS...WILL SUPPORT A THREAT FOR HEAVY RAINFALL. PW VALUES NEAR 1
INCH SUGGEST RATES LOCALLY EXCEEDING 1 INCH PER HOUR ARE POSSIBLE.

AT 0415Z...THE STRONGEST STORMS PER REGIONAL RADAR IMAGERY WERE
LOCATED OVER FAR NERN MS INTO HARDEMAN COUNTY TN...WITH A SECOND
ISOLATED STORM ALONG THE BORDER OF MARION/LAMAR COUNTIES IN NWRN AL.
WSR-88D VAD WIND PROFILERS SHOWED A 20 KT SWLY LLJ EXTENDING INTO
NERN MS PROVIDING LOW LEVEL WAA INTO THIS REGION.  THIS COMBINED
WITH A FEED OF HIGHER INSTABILITY /MUCAPE 2000-3000 J PER KG/
LOCATED OVER THE LOWER MS VALLEY INTO THE W/NWRN EXTENT OF THE NRN
MS/AL MCS IS EXPECTED TO MAINTAIN CONVECTION OVERNIGHT.  EFFECTIVE
BULK SHEAR AROUND 30 KT FAVORS A CONTINUED POTENTIAL FOR HAIL AND
STRONG WIND GUSTS IN THE SUSTAINED ACTIVITY. 

FARTHER S INTO CENTRAL AL...REGIONAL RADAR IMAGERY/LIGHTNING DATA
INDICATED A WEAKENING TREND WITH THIS REGION HAVING BEEN
CONVECTIVELY OVERTURNED.  THUS...MUCH OF THE ERN HALF TO TWO-THIRDS
OF WW 123 HAS A SUBSTANTIALLY DECREASED SEVERE WEATHER THREAT.

..PETERS.. 04/01/2012

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

ATTN...WFO...BMX...HUN...MOB...MEG...JAN...

LAT...LON   34968830 34188781 33518738 32908698 32658660 31998639
            32028694 32348756 32728807 33058830 33678882 34448925
            34948943 35288931 35248884 34968830

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 31, 7:27 PM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Calhoun, Chambers, Cherokee and 39 more	63 min
Mar 31, 8:14 PM CDT	Severe Thunderstorm Watch	SPC	Autauga, Bibb, Chilton, Colbert, Dallas, Fayette and 13 more	7 hr
Apr 1, 1:31 PM CDT	Mesoscale Discussion	SPC	Anderson, Blount, Campbell, Cocke, Fentress, Grainger and 11 more	89 min

Nearby

Mesoscale Discussions in Mississippi, 2012 Mesoscale Discussions in Alabama, 2012 Mesoscale Discussions in Tennessee, 2012 Every 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.