Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 249

March 12, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Mar 12, 2012, 4:02 PM CDT for 4 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued
Mar 12, 2012, 4:02 PM CDT (21:02 UTC)
Expired
Mar 12, 2012, 5:00 PM CDT
In force
58 min
Issued by
the Storm Prediction Center
All 42 counties

Chicot County, AR, East Carroll Parish, LA, Madison Parish, LA, Richland Parish, LA, West Carroll Parish, LA, Attala County, MS, Benton County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Lafayette County, MS, Leflore County, MS, Marshall County, MS, Montgomery County, MS, Panola County, MS, Pontotoc County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tunica 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, Haywood County, TN, Lauderdale County, TN, Shelby County, TN, Tipton County, TN

The radar

The Columbus AFB radar (KGWX), 157 km from the middle of the area, began a volume at 21:04 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

Little Rock, AR (KLZK), launched 12:00Z, 9.0 hours before the alert went out and 111 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 2012-03-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2012-03-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 140 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
728 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
130 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

260 
ACUS11 KWNS 122103
SWOMCD
SPC MCD 122102
MSZ000-TNZ000-ARZ000-LAZ000-122200-

MESOSCALE DISCUSSION 0249
NWS STORM PREDICTION CENTER NORMAN OK
0402 PM CDT MON MAR 12 2012

AREAS AFFECTED...NERN LA...NRN AND WRN MS...SWRN TN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 122102Z - 122200Z

A CONDITIONAL THREAT FOR LARGE HAIL/DMGG WINDS WILL EXIST LATE THIS
AFTERNOON AND EVENING ACROSS PORTIONS OF NERN LA...NRN AND WRN
MS...SWRN TN. EXPECTED ISOLATED NATURE OF THE THREAT LIMITS THE NEED
FOR A WW.

20Z VIS SAT IMAGERY SHOWS A MODEST CU FIELD DEVELOPING ALONG A BROAD
LOW-LEVEL THETA-E AXIS /LOCATED ALONG A LINE FROM 35 WSW IER TO 15
ENE OF JBR/. LOW-LEVEL MOISTURE ADVECTION AND HEATING HAVE RESULTED
IN MUCAPE GREATER THAN 1000 J/KG ACROSS THE AREA. ADDITIONALLY...
DEEP LAYER SHEAR NEAR 30 KT IS MARGINALLY FAVORABLE FOR A FEW
ROTATING STORMS. CONSIDERABLE UNCERTAINTY REMAINS REGARDING
CONVECTIVE INITIATION AND THUNDERSTORM COVERAGE. HOWEVER...
INITIATION OF STORMS OVER THE MID-MISSISSIPPI VALLEY MAY BE ENHANCED
BY A WEAK UPPER IMPULSE MOVING EWD ACROSS AR. IF THIS OCCURS AN
ISOLATED THREAT FOR LARGE HAIL AND DMGG WINDS IS POSSIBLE.

..MOSIER/ROGERS.. 03/12/2012

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

ATTN...WFO...MEG...JAN...LZK...SHV...

LAT...LON   33118954 32219089 32199160 32409201 35328993 36018951
            35408856 34778869 33118954

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 11, 8:44 PM CDTMesoscale DiscussionSPCChicot91 min
Mar 11, 11:17 PM CDTMesoscale DiscussionSPCAcadia, Ascension, Assumption, East Baton Rouge, Iberia, Iberville and 11 more88 min
Mar 12, 1:23 AM CDTMesoscale DiscussionSPCAscension, Assumption, Iberia, Iberville, Livingston, Saint Charles and 5 more2 hr
Mar 12, 8:55 AM CDTMesoscale DiscussionSPCAcadia, Ascension, Assumption, Iberville, Jefferson Davis, Lafayette and 5 more65 min

Nearby

Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in Louisiana, 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.