Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 455

April 5, 201221 counties in Alabama; Greene County, Wayne County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 5, 2012, 10:41 AM CDT for 21 counties in Alabama; Greene County, Wayne County, Mississippi. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued
Apr 5, 2012, 10:41 AM CDT (15:41 UTC)
Expired
Apr 5, 2012, 12:15 PM CDT
In force
94 min
Issued by
the Storm Prediction Center
All 23 counties

Autauga County, AL, Bibb County, AL, Butler County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Conecuh County, AL, Coosa County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Hale County, AL, Lowndes County, AL, Marengo County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Shelby County, AL, Washington County, AL, Wilcox County, AL, Greene County, MS, Wayne County, MS

The radar

The Birmingham radar (KBMX), 145 km from the middle of the area, began a volume at 15:41 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 12:00Z, 3.7 hours before the alert went out and 145 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, Birmingham, AL at 12:00Z on 2012-04-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 315 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, Birmingham, AL at 12:00Z on 2012-04-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -91 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
315 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
754 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
-91 m²/s²
0-3 km storm-relative helicity
-43 m²/s²
Significant tornado parameter
0.0
Supercell composite
-1.5

Open this sounding in Storm Lab

The text

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

710 
ACUS11 KWNS 051541
SWOMCD
SPC MCD 051541 
ALZ000-FLZ000-MSZ000-051715-

MESOSCALE DISCUSSION 0455
NWS STORM PREDICTION CENTER NORMAN OK
1041 AM CDT THU APR 05 2012

AREAS AFFECTED...CNTRL/SRN AL...SERN MS

CONCERNING...SEVERE THUNDERSTORM WATCH 143...

VALID 051541Z - 051715Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 143
CONTINUES.

LARGELY SUPPORTED BY FORCING FOR UPWARD VERTICAL MOTION DOWNSTREAM
OF THE EAST SOUTHEASTWARD PROGRESSING OZARK PLATEAU CLOSED
LOW...VIGOROUS CONVECTIVE DEVELOPMENT PERSISTS ALONG THE LEADING
EDGE OF A CONVECTIVELY GENERATED COLD POOL.  THIS FEATURE HAS SLOWED
SOME...TO AROUND 25-30 KT...BUT THUNDERSTORMS ALONG THE BOUNDARY
HAVE SHOWN SOME INTENSIFYING TRENDS TO THE SOUTHWEST AND SOUTH OF
TUSCALOOSA.  THIS APPEARS TO BE IN THE EXIT REGION OF A 60+ KT 500
MB JET STREAK.  DESPITE THE RATHER MODEST STRENGTH AND WESTERLY
COMPONENT OF THE LOW-LEVEL FLOW FIELDS...THE DOWNWARD TRANSFER OF
HIGHER MOMENTUM FROM ALOFT COULD EVENTUALLY CONTRIBUTE TO AN
EASTWARD ACCELERATION OF THE LINE AND INCREASING DAMAGING WIND
POTENTIAL ACROSS CENTRAL ALABAMA BY EARLY AFTERNOON.  BOUNDARY LAYER
DESTABILIZATION REMAINS THE PRIMARY UNCERTAINTY WITH REGARD TO HOW
QUICKLY THIS COULD OCCUR...WITH CONSIDERABLE CLOUD COVER AND LIGHT
CONVECTIVE PRECIPITATION HAMPERING SURFACE HEATING ACROSS ALL BUT
PORTIONS OF SOUTHWESTERN ALABAMA.  OTHERWISE...LARGE HAIL WILL
REMAIN A THREAT IN PERIODIC STRONGER UPDRAFT PULSES.

..KERR.. 04/05/2012

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

ATTN...WFO...BMX...MOB...JAN...

LAT...LON   31968859 32938774 33318711 33348622 32068588 31298645
            30988763 31168867 31598887 31968859

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 5, 7:36 AM CDTMesoscale DiscussionSPCChoctaw, Greene, Hale, Marengo, Perry, Pickens and 2 more54 min
Apr 5, 9:14 AM CDTSevere Thunderstorm WatchSPCAutauga, Barbour, Bibb, Bullock, Butler, Chambers and 34 more8 hr
Apr 5, 12:09 PM CDTMesoscale DiscussionSPCColbert, Cullman, Franklin, Lauderdale, Lawrence, Limestone and 4 more96 min
Apr 5, 1:12 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Chambers, Clay, Coffee, Covington and 11 more93 min
Apr 5, 1:21 PM CDTSevere Thunderstorm WatchSPCColbert, DeKalb, Franklin, Jackson, Lauderdale, Lawrence and 4 more8 hr
Apr 5, 1:58 PM CDTSevere Thunderstorm WatchSPCCoffee, Dale, Geneva, Henry, Houston6 hr
Apr 5, 3:06 PM CDTMesoscale DiscussionSPCColbert, DeKalb, Franklin, Jackson, Lauderdale, Lawrence and 4 more54 min
Apr 5, 3:46 PM CDTMesoscale DiscussionSPCBlount, Calhoun, Cullman, Etowah, Fayette, Jefferson and 7 more59 min
Apr 5, 3:49 PM CDTMesoscale DiscussionSPCGeneva, Henry, Houston86 min
Apr 5, 6:14 PM CDTSevere Thunderstorm WatchSPCAutauga, Bibb, Blount, Bullock, Calhoun, Chambers and 21 more3 hr
Apr 5, 6:15 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Bullock, Calhoun, Chambers and 23 more45 min
Apr 5, 1:35 AM CDTMesoscale DiscussionSPCAdams, Amite, Claiborne, Copiah, Franklin, Hinds and 8 more85 min
Apr 5, 1:53 AM CDTTornado WatchSPCAdams, Amite, Attala, Bolivar, Carroll, Choctaw and 45 more9 hr
Apr 5, 3:30 AM CDTMesoscale DiscussionSPCAdams, Amite, Attala, Carroll, Claiborne, Copiah and 39 more2 hr
Apr 5, 3:56 AM CDTTornado WatchSPCAmite, Hancock, Harrison, Jackson, Pearl River, Pike and 2 more6 hr
Apr 5, 10:43 AM CDTSevere Thunderstorm WatchSPCClarke, Covington, Forrest, Franklin, Jasper, Jefferson Davis and 7 more4 hr
Apr 5, 12:18 PM CDTSevere Thunderstorm WatchSPCAlcorn, Benton, Calhoun, Chickasaw, Coahoma, DeSoto and 16 more5 hr
Apr 5, 2:22 PM CDTMesoscale DiscussionSPCAlcorn, Benton, Calhoun, Chickasaw, DeSoto, Itawamba and 14 more53 min

Nearby

Mesoscale 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.