Alert archive / Tennessee / Mesoscale Discussions in 2012

Mesoscale Discussion 254

March 14, 20127 counties in Alabama; Alcorn County, Prentiss County, Tishomingo County, Mississippi; 14 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Mar 14, 2012, 3:01 PM CDT for 7 counties in Alabama; Alcorn County, Prentiss County, Tishomingo County, Mississippi; 14 counties in Tennessee. It was in force for 104 min.

The area

The outline as issued.

The facts

Issued
Mar 14, 2012, 3:01 PM CDT (20:01 UTC)
Expired
Mar 14, 2012, 4:45 PM CDT
In force
104 min
Issued by
the Storm Prediction Center
All 24 counties

Colbert County, AL, Franklin County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Morgan County, AL, Alcorn County, MS, Prentiss County, MS, Tishomingo County, MS, Chester County, TN, Decatur County, TN, Giles County, TN, Hardin County, TN, Henderson County, TN, Hickman County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Marshall County, TN, Maury County, TN, McNairy County, TN, Perry County, TN, Wayne County, TN

The radar

The Columbus AFB radar (KGWX), 139 km from the middle of the area, began a volume at 20:04 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

Nashville Metro, TN (KBNA), launched 12:00Z, 8.0 hours before the alert went out and 158 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, Nashville Metro, TN at 12:00Z on 2012-03-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 486 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, Nashville Metro, TN at 12:00Z on 2012-03-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -9 square meters per square second.1939Sfc1 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
486 J/kg
Mixed-layer CIN
-56 J/kg
Mixed-layer LCL
1099 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-9 m²/s²
0-3 km storm-relative helicity
17 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.

685 
ACUS11 KWNS 142002
SWOMCD
SPC MCD 142001 COR
ALZ000-TNZ000-MSZ000-142145-

MESOSCALE DISCUSSION 0254
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT WED MAR 14 2012

AREAS AFFECTED...FAR NERN MS...NRN AL...S-CNTRL TN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 142001Z - 142145Z

CORRECTED FOR GEOGRAPHIC REFERENCE

A MARGINAL THREAT FOR DMGG WINDS WILL EXIST LATE THIS AFTERNOON AND
EVENING ACROSS PORTIONS OF FAR NERN MS...NRN AL...S-CNTRL TN.
EXPECTED ISOLATED NATURE OF THE THREAT LIMITS THE NEED FOR A WW.

TEMPERATURES HAVE WARMED INTO THE UPPER 70S AND LOW 80S AND MOISTURE
ADVECTION ASSOCIATED WITH RETURN FLOW ACROSS A BROAD WARM SECTOR HAS
KEPT DEWPOINTS IN THE MID 60S. ADDITIONALLY... NEAR DRY ADIABATIC
LAPSE RATES ARE PRESENT ABOVE 700 MB. AS A RESULT...AN UNCAPPED
ENVIRONMENT WITH SBCAPE VALUES AOA 2500 J/KG EXISTS OVER THE REGION.
HOWEVER...THE SEVERE THREAT IS EXPECTED TO BE LIMITED...OWING TO THE
LACK OF STRONG FORCING AND EFFECTIVE BULK SHEAR OF 25-30 KT /LOWER
MARGINS FOR PERSISTENT STORMS/. CONSEQUENTLY...A MARGINAL THREAT FOR
DMGG WINDS IS POSSIBLE BUT THE LIMITED COVERAGE WILL PRECLUDE THE
NEED FOR A WW.

..MOSIER.. 03/14/2012

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

ATTN...WFO...OHX...BMX...HUN...MEG...

LAT...LON   35508877 35908799 35758668 35168634 34528643 34278695
            34258776 34468840 35028897 35508877

Nearby

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