Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 419

April 24, 20215 counties in Alabama; George County, Greene County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2021, 4:26 AM CDT for 5 counties in Alabama; George County, Greene County, Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 24, 2021, 4:26 AM CDT (09:26 UTC)
Expired
Apr 24, 2021, 6:30 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Tornado watch 105

Counties Conecuh County, AL, Covington County, AL, Escambia County, AL, Monroe County, AL, Washington County, AL, George County, MS, Greene County, MS

The radar

The Mobile radar (KMOB), 78 km from the middle of the area, began a volume at 09:30 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 9.4 hours before the alert went out and 214 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, Slidell Radar S, LA at 00:00Z on 2021-04-24Temperature 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, Slidell Radar S, LA at 00:00Z on 2021-04-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 156 square meters per square second.1939587897117Sfc1 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
873 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
156 m²/s²
0-3 km storm-relative helicity
263 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

205 
ACUS11 KWNS 240926
SWOMCD
SPC MCD 240926 
ALZ000-FLZ000-MSZ000-241130-

Mesoscale Discussion 0419
NWS Storm Prediction Center Norman OK
0426 AM CDT Sat Apr 24 2021

Areas affected...southern Mississippi and Alabama...western Florida
Panhandle

Concerning...Tornado Watch 105...

Valid 240926Z - 241130Z

The severe weather threat for Tornado Watch 105 continues.

SUMMARY...A corridor of enhanced damaging-wind risk as well as
tornado and hail threat is currently evolving over southern
Mississippi and Alabama. Another watch may eventually be needed
downstream of watch 105.

DISCUSSION...A long-lived squall line continues to move east across
LA and MS, and has recently become better oriented relative to the
deep-layer shear to enhance severe potential. The air mass continues
to moisten ahead of this line, with falling surface pressures. Very
strong shear will favor damaging gusts as well as a QLCS tornado
threat.

Ahead of this line and along the warm front, a supercell is evident
into over Clarke and Monroe Counties in AL. Surface observations
ahead of this storms continue to warm, suggesting a continued severe
threat all the way across southern AL this morning. The threat may
extend east of WW 105 prior to expiration, suggesting another watch
may be needed farther east.

..Jewell.. 04/24/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MOB...

LAT...LON   31628788 31758662 31608638 31358627 31168634 30968753
            30788869 30818891 30948887 31138881 31298876 31478837
            31628788

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 24, 1:00 AM CDTMesoscale DiscussionSPCBaldwin, Coffee, Conecuh, Covington, Escambia, Geneva and 2 more3 hr
Apr 24, 1:00 AM CDTMesoscale DiscussionSPCBaldwin, Coffee, Conecuh, Covington, Escambia, Geneva and 2 more3 hr
Apr 24, 1:23 AM CDTTornado WatchSPCBaldwin, Clarke, Conecuh, Covington, Escambia, Mobile and 2 more8 hr
Apr 24, 3:04 AM CDTMesoscale DiscussionSPCBaldwin, Mobile, Washington116 min
Apr 24, 5:22 AM CDTTornado WatchSPCCoffee, Dale, Geneva, Henry, Houston9 hr
Apr 24, 7:29 AM CDTMesoscale DiscussionSPCCoffee, Dale, Geneva, Henry, Houston91 min
Apr 24, 12:29 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Conecuh, Escambia, Marengo and 4 more2 hr
Apr 24, 1:17 PM CDTSevere Thunderstorm WatchSPCAutauga, Baldwin, Barbour, Bullock, Butler, Choctaw and 23 more8 hr
Apr 24, 1:22 PM CDTMesoscale DiscussionSPCBlount, Calhoun, Cherokee, Clay, Cleburne, Colbert and 22 more113 min
Apr 24, 3:40 PM CDTMesoscale DiscussionSPCAutauga, Barbour, Bullock, Butler, Clarke, Coffee and 19 more95 min
Apr 24, 4:52 PM CDTSevere Thunderstorm WatchSPCBibb, Blount, Calhoun, Chambers, Cherokee, Chilton and 15 more4 hr
Apr 24, 5:56 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Coffee, Dale, Henry, Houston and 1 more94 min
Apr 24, 6:13 PM CDTMesoscale DiscussionSPCCalhoun, Chambers, Cherokee, Clay, Cleburne, Coosa and 6 more2 hr
Apr 23, 8:30 PM CDTTornado WatchSPCAdams, Amite, Claiborne, Copiah, Covington, Forrest and 15 more8 hr
Apr 23, 10:29 PM CDTMesoscale DiscussionSPCAmite, Forrest, George, Hancock, Lamar, Marion and 6 more2 hr

Nearby

Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Mississippi, 2021Every mesoscale discussion in 2021

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.