Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 401

March 31, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2012, 7:27 PM CDT for 4 states. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Mar 31, 2012, 7:27 PM CDT (00:27 UTC)
Expired: Mar 31, 2012, 8:30 PM CDT
In force: 63 min
Issued by: the Storm Prediction Center

All 73 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Colbert County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Elmore County, AL, Etowah County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Jackson County, AL, Jefferson County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Lee County, AL, Limestone County, AL, Lowndes County, AL, Macon County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Montgomery County, AL, Morgan County, AL, Perry County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Cherokee County, GA, Cobb County, GA, Dade County, GA, Dawson County, GA, Douglas County, GA, Fannin County, GA, Floyd County, GA, Gilmer County, GA, Gordon County, GA, Haralson County, GA, Heard County, GA, Murray County, GA, Paulding County, GA, Pickens County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Tishomingo County, MS, Franklin County, TN, Giles County, TN, Hardin County, TN, Lincoln County, TN, Moore County, TN, Wayne County, TN

The radar

The Birmingham radar (KBMX), 100 km from the middle of the area, began a volume at 00:25 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.

Severe Thunderstorm Watch 123Mar 31, 8:15 PM CDT

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 0.5 hours before the alert went out and 100 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.

109 
ACUS11 KWNS 010028
SWOMCD
SPC MCD 010027
GAZ000-ALZ000-TNZ000-MSZ000-010130-

MESOSCALE DISCUSSION 0401
NWS STORM PREDICTION CENTER NORMAN OK
0727 PM CDT SAT MAR 31 2012

AREAS AFFECTED...SRN MIDDLE TN/NERN MS/NRN AND CENTRAL AL/NRN GA

CONCERNING...SEVERE THUNDERSTORM WATCH 121...122...

VALID 010027Z - 010130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
121...122...CONTINUES.

A LOCAL WFO SWD EXTENSION OF WW 122 IN AREA AND TIME OR A NEW WATCH
ISSUANCE NEEDS TO BE CONSIDERED AS THE CLUSTER OF TSTMS ACROSS NRN
AL PROGRESSES SWD THIS EVENING INTO A MODERATELY UNSTABLE AIR MASS.

AT 00Z...REGIONAL RADAR IMAGERY SHOWED SEVERAL STRONG TO SEVERE
STORMS MOVING SWD PREDOMINATELY THROUGH NRN AND CENTRAL AL...WITH A
COUPLE OF STORMS AFFECTING FAR NERN MS...SRN MIDDLE TN...AND OVER
NWRN GA.  THE ENVIRONMENT DOWNSTREAM OF THIS ONGOING ACTIVITY IS
JUST BEGINNING TO SLOWLY STABILIZE...THOUGH REMAINS SUFFICIENTLY
UNSTABLE /MLCAPE 1500-2000 J PER KG/ TO MAINTAIN THE SWD MOVING
CLUSTER OF STORMS WITH AN ATTENDANT SEVERE WEATHER THREAT. EFFECTIVE
BULK SHEAR OF 30-35 KT SUPPORTS MULTICELLS AND SUPERCELLS. THESE
FACTORS COMBINED WITH STEEP LAPSE RATES PER 00Z FFC SOUNDING /8 C/KM
AT 700-500 MB/ FAVOR A CONTINUED THREAT FOR HAIL...SOME VERY
LARGE...AS HAS ALREADY BEEN REPORTED ACROSS SRN MIDDLE TN AND NRN
AL...AND MOST RECENTLY IN CULLMAN COUNTY AL AT 2354Z WITH 2.50 INCH
HAIL.

15Z SREF AND 19Z/20Z EXPERIMENTAL WRF-HRRR SUPPORT THE SWD EXTENSION
OF WW 122 AS EACH MODEL SUGGESTS ONGOING CONVECTION MOVES INTO MORE
OF CENTRAL AL BEFORE WEAKENING.

..PETERS.. 04/01/2012

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG...JAN...

LAT...LON   33058509 32188530 32088669 32318733 32388835 32688838
            34218834 34958848 35388806 35288761 35118736 35148714
            35548666 35248581 34978569 34978415 34538405 33898441
            33058509

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 31, 8:14 PM CDT	Severe Thunderstorm Watch	SPC	Autauga, Bibb, Chilton, Colbert, Dallas, Fayette and 13 more	7 hr
Mar 31, 11:33 PM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Dallas, Fayette, Greene, Hale and 6 more	57 min
Apr 1, 1:31 PM CDT	Mesoscale Discussion	SPC	Rabun	89 min

Nearby

Mesoscale Discussions in Alabama, 2012 Mesoscale Discussions in Georgia, 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.