Alert archive / Mississippi / Mesoscale Discussions in 2018

Mesoscale Discussion 1102

July 20, 201826 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jul 20, 2018, 1:23 PM CDT for 26 counties in Mississippi. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
Jul 20, 2018, 1:23 PM CDT (18:23 UTC)
Expired
Jul 20, 2018, 3:00 PM CDT
In force
97 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 26 counties

Attala County, MS, Carroll County, MS, Choctaw County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Jasper County, MS, Jones County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Warren County, MS, Washington County, MS, Winston County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 45 km from the middle of the area, began a volume at 18:26 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 6.4 hours before the alert went out and 44 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, Jackson, MS at 12:00Z on 2018-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1428 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, Jackson, MS at 12:00Z on 2018-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 56 square meters per square second.193958Sfc1 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
1428 J/kg
Mixed-layer CIN
-119 J/kg
Mixed-layer LCL
986 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
56 m²/s²
0-3 km storm-relative helicity
153 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.7

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 19, 8:02 PM CDTMesoscale DiscussionSPCCoahoma, Tunica118 min
Jul 19, 8:54 PM CDTSevere Thunderstorm WatchSPCCoahoma, DeSoto, Lafayette, Marshall, Panola, Quitman and 2 more114 min
Jul 19, 11:21 PM CDTMesoscale DiscussionSPCAttala, Bolivar, Calhoun, Carroll, Coahoma, Grenada and 17 more114 min
Jul 20, 2:11 PM CDTSevere Thunderstorm WatchSPCClarke, Covington, Forrest, Hinds, Jasper, Jefferson Davis and 14 more3 hr
Jul 20, 5:54 PM CDTMesoscale DiscussionSPCAlcorn, Benton, Chickasaw, Coahoma, DeSoto, Itawamba and 13 more3 hr
Jul 20, 6:22 PM CDTTornado WatchSPCAlcorn, Benton, Calhoun, Chickasaw, Coahoma, DeSoto and 16 more8 hr

Nearby

Mesoscale Discussions in Mississippi, 2018Every mesoscale discussion in 2018

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.