Alert archive / Tennessee / Mesoscale Discussions in 2005

Mesoscale Discussion 642

April 21, 200521 counties in Alabama; 24 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2005, 9:23 PM CDT for 21 counties in Alabama; 24 counties in Tennessee. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
Apr 21, 2005, 9:23 PM CDT (02:23 UTC)
Expired
Apr 21, 2005, 11:00 PM CDT
In force
97 min
Issued by
the Storm Prediction Center
All 45 counties

Bibb County, AL, Blount County, AL, Chilton County, AL, Colbert County, AL, Cullman County, AL, Fayette County, AL, Franklin County, AL, Hale County, AL, Jefferson County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Perry County, AL, Shelby County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Bedford County, TN, Benton County, TN, Cheatham County, TN, Davidson County, TN, Decatur County, TN, Dickson County, TN, Giles County, TN, Henry County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Marshall County, TN, Maury County, TN, Montgomery County, TN, Moore County, TN, Perry County, TN, Rutherford County, TN, Stewart County, TN, Wayne County, TN, Williamson County, TN, Wilson County, TN

The radar

The Northeast Alabama radar (KHTX), 112 km from the middle of the area, began a volume at 02:24 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 00:00Z, 2.4 hours before the alert went out and 167 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 2005-04-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 376 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 00:00Z on 2005-04-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 79 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
376 J/kg
Mixed-layer CIN
-131 J/kg
Mixed-layer LCL
1046 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
79 m²/s²
0-3 km storm-relative helicity
137 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 22, 5:36 AM CDTMesoscale DiscussionSPCColbert, Cullman, Franklin, Jackson, Lauderdale, Lawrence and 5 more84 min
Apr 22, 9:15 AM CDTMesoscale DiscussionSPCBibb, Chilton, Fayette, Greene, Hale, Jefferson and 4 more90 min
Apr 22, 9:50 AM CDTSevere Thunderstorm WatchSPCAutauga, Bibb, Blount, Calhoun, Chambers, Cherokee and 24 more5 hr
Apr 22, 12:41 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Chambers, Chilton, Clay, Coosa and 12 more64 min
Apr 22, 2:35 PM CDTSevere Thunderstorm WatchSPCAutauga, Barbour, Bibb, Blount, Bullock, Butler and 38 more6 hr
Apr 22, 2:49 PM CDTMesoscale DiscussionSPCColbert, Franklin, Jackson, Lauderdale, Lawrence, Limestone and 2 more86 min
Apr 22, 3:35 PM CDTSevere Thunderstorm WatchSPCColbert, DeKalb, Jackson, Lauderdale, Lawrence, Limestone and 2 more5 hr
Apr 22, 5:40 PM CDTSevere Thunderstorm WatchSPCCalhoun, Cherokee, Cleburne, DeKalb, Etowah, Jackson5 hr
Apr 22, 6:15 PM CDTSevere Thunderstorm WatchSPCBarbour, Coffee, Dale, Geneva, Henry, Houston and 1 more6 hr
Apr 22, 6:40 PM CDTMesoscale DiscussionSPCJackson, Madison95 min
Apr 21, 8:19 PM CDTMesoscale DiscussionSPCDyer, Lake, Obion86 min
Apr 22, 3:09 AM CDTMesoscale DiscussionSPCDyer, Lake, Obion66 min
Apr 22, 11:18 AM CDTMesoscale DiscussionSPCBlount, Sevier117 min
Apr 22, 5:17 PM CDTMesoscale DiscussionSPCAnderson, Bledsoe, Blount, Bradley, Campbell, Claiborne and 23 more58 min

Nearby

Mesoscale Discussions in Tennessee, 2005Mesoscale Discussions in Alabama, 2005Every mesoscale discussion in 2005

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.