Alert archive / Alabama / Mesoscale Discussions in 2009

Mesoscale Discussion 461

April 12, 20094 states

The Storm Prediction Center issued this mesoscale discussion at Apr 12, 2009, 10:42 PM CDT for 4 states. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued
Apr 12, 2009, 10:42 PM CDT (03:42 UTC)
Expired
Apr 13, 2009, 12:15 AM CDT
In force
93 min
Issued by
the Storm Prediction Center
All 56 counties

Autauga County, AL, Baldwin County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Chambers County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Coffee County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Geneva County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pike County, AL, Shelby County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Lamar County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Wayne County, MS

The radar

The Birmingham radar (KBMX), 135 km from the middle of the area, began a volume at 03:45 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.

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 3.7 hours before the alert went out and 136 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 00:00Z on 2009-04-13Temperature 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, Birmingham, AL at 00:00Z on 2009-04-13The 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
1755 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
406 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.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 12, 8:07 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Butler, Chilton, Choctaw, Clarke and 12 more53 min
Apr 12, 8:30 PM CDTTornado WatchSPCChoctaw, Clarke, Greene, Hale, Marengo, Mobile and 2 more6 hr
Apr 12, 11:01 PM CDTTornado WatchSPCAutauga, Baldwin, Butler, Conecuh, Covington, Crenshaw and 8 more4 hr
Apr 13, 1:57 AM CDTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Coffee, Conecuh and 13 more63 min
Apr 13, 2:33 AM CDTTornado WatchSPCBaldwin, Barbour, Bullock, Butler, Clarke, Coffee and 14 more7 hr
Apr 13, 4:32 AM CDTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Coffee, Conecuh and 10 more58 min
Apr 13, 7:27 AM CDTMesoscale DiscussionSPCBaldwin, Coffee, Covington, Dale, Escambia, Geneva and 3 more2 hr
Apr 13, 9:12 AM CDTTornado WatchSPCCoffee, Covington, Dale, Escambia, Geneva, Henry and 1 more9 hr
Apr 13, 11:15 AM CDTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Clarke, Coffee and 11 more90 min
Apr 13, 12:09 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lauderdale, Lawrence, Limestone, Marion and 2 more66 min
Apr 13, 12:58 PM CDTTornado WatchSPCColbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more7 hr
Apr 13, 4:16 PM CDTSevere Thunderstorm WatchSPCChoctaw4 hr
Apr 13, 5:52 PM CDTMesoscale DiscussionSPCBlount, Cullman, DeKalb, Etowah, Fayette, Jackson and 10 more53 min
Apr 13, 6:55 PM CDTMesoscale DiscussionSPCBibb, Chilton, Choctaw, Clarke, Dallas, Greene and 9 more95 min
Apr 13, 11:32 AM CDTTornado WatchSPCBaker, Bradford, Clay, Columbia, Duval, Gilchrist and 5 more6 hr
Apr 13, 5:22 PM CDTMesoscale DiscussionSPCAlachua, Baker, Bradford, Citrus, Clay, Columbia and 18 more83 min
Apr 13, 5:53 PM CDTTornado WatchSPCAlachua, Baker, Bradford, Calhoun, Clay, Columbia and 22 more5 hr
Apr 13, 1:39 PM CDTMesoscale DiscussionSPCAscension, Avoyelles, Concordia, East Baton Rouge, East Feliciana, Iberville and 8 more66 min

Nearby

Mesoscale Discussions in Alabama, 2009Mesoscale Discussions in Mississippi, 2009Mesoscale Discussions in Florida, 2009Every mesoscale discussion in 2009

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.