Alert archive / Mississippi / Mesoscale Discussions in 2021

Mesoscale Discussion 1314

July 18, 2021Ashley County, Chicot County, Drew County, Arkansas; 17 parishes in Louisiana; 21 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2021, 2:14 PM CDT for Ashley County, Chicot County, Drew County, Arkansas; 17 parishes in Louisiana; 21 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 18, 2021, 2:14 PM CDT (19:14 UTC)
Expired: Jul 18, 2021, 4:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

All 41 counties

Ashley County, AR, Chicot County, AR, Drew County, AR, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Bolivar County, MS, Claiborne County, MS, Copiah County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Sunflower County, MS, Warren County, MS, Washington County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 129 km from the middle of the area, began a volume at 19:17 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, 7.2 hours before the alert went out and 119 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: 505 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 870 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

692 
ACUS11 KWNS 181914
SWOMCD
SPC MCD 181914 
MSZ000-ARZ000-LAZ000-182115-

Mesoscale Discussion 1314
NWS Storm Prediction Center Norman OK
0214 PM CDT Sun Jul 18 2021

Areas affected...Northeast Louisiana...west-central Mississippi

Concerning...Severe potential...Watch unlikely 

Valid 181914Z - 182115Z

Probability of Watch Issuance...5 percent

SUMMARY...Locally strong/damaging wind gusts will be possible this
afternoon. No WW is expected this afternoon.

DISCUSSION...A loosely organized line of storm associated with a
weak MCV in southern Arkansas is continuing to move southeastward
into a destabilizing airmass. 2000-2500 J/kg MLCAPE has developed as
a very moist boundary layer has warmed to near or above 90 F. An
earlier cluster of storms this morning has left an outflow boundary
across parts of central Mississippi. The greatest potential for
damaging wind gusts will be along and southwestward of this boundary
where storms may become slightly better organized. Overall,
low-level/deep-layer shear are weak and should keep intense
thunderstorm activity relatively localized. A few damaging downburst
winds are possible this afternoon. The marginal and localized threat
is not expected to require a WW.

..Wendt/Dial.. 07/18/2021

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

ATTN...WFO...JAN...LZK...SHV...

LAT...LON   32689328 33249247 33809128 33869067 33438999 32898949
            32428921 32008941 31719027 31409116 31669212 31899269
            32249314 32689328

Nearby

Mesoscale Discussions in Mississippi, 2021 Mesoscale Discussions in Louisiana, 2021 Mesoscale Discussions in Arkansas, 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.