Alert archive / Mississippi / Mesoscale Discussions in 2021

Mesoscale Discussion 950

June 13, 20214 counties in Alabama; 8 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jun 13, 2021, 1:25 PM CDT for 4 counties in Alabama; 8 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 13, 2021, 1:25 PM CDT (18:25 UTC)
Expired: Jun 13, 2021, 3:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 265

Counties Choctaw County, AL, Greene County, AL, Marengo County, AL, Sumter County, AL, Clarke County, MS, Kemper County, MS, Lauderdale County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Scott County, MS, Winston County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 144 km from the middle of the area, began a volume at 18:25 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

Jackson, MS (KJAN), launched 12:00Z, 6.4 hours before the alert went out and 152 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2570 J/kg
Mixed-layer CIN: -25 J/kg
Mixed-layer LCL: 869 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

527 
ACUS11 KWNS 131826
SWOMCD
SPC MCD 131825 
ALZ000-MSZ000-132030-

Mesoscale Discussion 0950
NWS Storm Prediction Center Norman OK
0125 PM CDT Sun Jun 13 2021

Areas affected...east-central MS...west-central AL

Concerning...Severe Thunderstorm Watch 265...

Valid 131825Z - 132030Z

The severe weather threat for Severe Thunderstorm Watch 265
continues.

SUMMARY...A developing thunderstorm cluster of northeast
MS/northwest AL at 120pm is forecast to congeal and move southward
into east-central MS and west-central AL.  The potential for strong
to severe gusts (50-70 mph) is expected to increase coincident with
the organization into a small cluster.  The threat for severe will
probably maximize during the 3-5pm period.

DISCUSSION...Visible satellite imagery shows a thunderstorm cluster
continuing to expand in spatial coverage across northeast MS and
adjacent parts of northwest/west-central AL.  The boundary layer to
the south of the storms is very unstable (2800 J/kg MLCAPE)
according to the 1pm Jackson, MS raob.  Although the flow in the
lowest 5 km is weak (at or below 15 kt), flow strengthens to 25-35
kt in the mid levels.  A gradual storm-scale evolution from
individual cells to a multicell cluster or two is forecast through
the mid afternoon.  The more intense cores will favor water-loaded
downdraft/microburst potential this afternoon.  Widely scattered
50-60 mph gusts are possible (localized gusts 60-70 mph) and wind
damage will accompany these gusts.

..Smith.. 06/13/2021

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

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

LAT...LON   31848795 32068918 32428956 33098941 33468900 33068786
            32698765 32138768 31848795

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 13, 10:45 AM CDT	Mesoscale Discussion	SPC	Choctaw, Colbert, Cullman, Fayette, Franklin, Greene and 10 more	60 min
Jun 13, 12:22 PM CDT	Severe Thunderstorm Watch	SPC	Choctaw, Clarke, Fayette, Greene, Hale, Lamar and 9 more	9 hr
Jun 13, 12:51 PM CDT	Mesoscale Discussion	SPC	Mobile	114 min
Jun 13, 3:43 PM CDT	Mesoscale Discussion	SPC	Covington, Jasper, Jones, Leake, Newton, Scott and 1 more	2 hr

Nearby

Mesoscale Discussions in Mississippi, 2021 Mesoscale Discussions in Alabama, 2021 Every 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.