Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 284
The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 3:56 PM CDT for 12 counties in Alabama; 23 counties in Mississippi. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- Mar 27, 2021, 3:56 PM CDT (20:56 UTC)
- Expired
- Mar 27, 2021, 5:30 PM CDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 35 counties
Cullman County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Jefferson County, AL, Lamar County, AL, Marion County, AL, Morgan County, AL, Pickens County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Itawamba County, MS, Kemper County, MS, Leake County, MS, Lee County, MS, Leflore County, MS, Lowndes County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Noxubee County, MS, Oktibbeha County, MS, Pontotoc County, MS, Webster County, MS, Winston County, MS
The radar
The Columbus AFB radar (KGWX), 31 km from the middle of the area, began a volume at 20:55 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, 8.9 hours before the alert went out and 150 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.
- Mixed-layer CAPE
- 1085 J/kg
- Mixed-layer CIN
- -47 J/kg
- Mixed-layer LCL
- 610 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 164 m²/s²
- 0-3 km storm-relative helicity
- 219 m²/s²
- Significant tornado parameter
- 1.0
- Supercell composite
- 5.2
The text
As transmitted.
490
ACUS11 KWNS 272056
SWOMCD
SPC MCD 272056
ALZ000-MSZ000-272230-
Mesoscale Discussion 0284
NWS Storm Prediction Center Norman OK
0356 PM CDT Sat Mar 27 2021
Areas affected...Portions of northern/central MS/AL
Concerning...Severe potential...Watch possible
Valid 272056Z - 272230Z
Probability of Watch Issuance...40 percent
SUMMARY...It remains unclear whether robust storms will develop this
afternoon. If they do, then isolated large hail, strong wind gusts,
and perhaps a tornado may occur. Watch issuance is possible.
DISCUSSION...It appears that convective temperatures have been
breached across east-central MS into northern/central AL, as
multiple lightning flashes have recently been observed in otherwise
showery convection. Temperatures in the 80s and dewpoints in the mid
to upper 60s are supporting MLCAPE in the 1500-2000 J/kg range.
Along with 45-55 kt of effective bulk shear, this environment
conditionally supports a supercell threat. The main uncertainty is
whether multiple robust storms will develop since the main forcing
for storms is just a broad area of weak low-level warm advection.
Still, if current radar trends continue, then isolated large hail
and strong/gusty winds may become a threat this afternoon. A tornado
cannot be ruled out either, although the low-level flow is not that
strong per KBMX and KGWX VWPs. Convective trends will be closely
monitored for possible watch issuance.
..Gleason/Thompson.. 03/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MEG...JAN...
LAT...LON 34378646 33158685 32708796 32498871 32798969 33069057
33679050 34198923 34458798 34548705 34378646SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 27, 2:05 AM CDT | Mesoscale Discussion | SPC | Colbert, Lauderdale, Limestone | 115 min |
| Mar 27, 11:55 AM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Jackson, Lauderdale, Lawrence, Limestone and 1 more | 3 hr |
| Mar 27, 1:51 PM CDT | Tornado Watch | SPC | Colbert, Jackson, Lauderdale, Limestone, Madison | 7 hr |
| Mar 27, 3:25 PM CDT | Tornado Watch | SPC | Bolivar, Washington | 10 hr |
| Mar 27, 6:42 PM CDT | Mesoscale Discussion | SPC | DeSoto, Tunica | 2 hr |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Alabama, 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.