Alert archive / Mississippi / Mesoscale Discussions in 2017

Mesoscale Discussion 889

May 27, 201714 counties in Alabama; 18 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 27, 2017, 11:46 PM CDT for 14 counties in Alabama; 18 counties in Mississippi. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 27, 2017, 11:46 PM CDT (04:46 UTC)
Expired: May 28, 2017, 12:45 AM CDT
In force: 59 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 32 counties

Bibb County, AL, Calhoun County, AL, Clay County, AL, Cleburne County, AL, Fayette County, AL, Jefferson County, AL, Lamar County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Leflore County, MS, Lowndes County, MS, Monroe County, MS, Montgomery County, MS, Noxubee County, MS, Oktibbeha County, MS, Tallahatchie County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS

The radar

The Columbus AFB radar (KGWX), 30 km from the middle of the area, began a volume at 04:46 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

Birmingham, AL (KBMX), launched 00:00Z, 4.8 hours before the alert went out and 163 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: 1881 J/kg
Mixed-layer CIN: -85 J/kg
Mixed-layer LCL: 1085 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 183 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 10.1

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.

Issued	Product	Office	Counties	Lasted
May 27, 9:07 PM CDT	Severe Thunderstorm Watch	SPC	Blount, Cherokee, Colbert, Cullman, DeKalb, Etowah and 13 more	8 hr
May 28, 2:11 AM CDT	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 23 more	2 hr
May 28, 2:53 AM CDT	Severe Thunderstorm Watch	SPC	Calhoun, Chambers, Chilton, Clay, Cleburne, Coosa and 6 more	4 hr
May 28, 10:59 AM CDT	Mesoscale Discussion	SPC	Baldwin, Covington, Escambia, Geneva, Mobile	2 hr
May 27, 9:26 PM CDT	Mesoscale Discussion	SPC	DeSoto	94 min
May 27, 9:59 PM CDT	Tornado Watch	SPC	Alcorn, Benton, DeSoto, Itawamba, Lafayette, Lee and 9 more	2 hr
May 28, 12:18 AM CDT	Severe Thunderstorm Watch	SPC	Alcorn, Benton, Bolivar, Calhoun, Carroll, Chickasaw and 27 more	6 hr
May 28, 4:59 AM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, Humphreys, Leflore, Sunflower, Washington	2 hr

Nearby

Mesoscale Discussions in Mississippi, 2017 Mesoscale Discussions in Alabama, 2017 Every mesoscale discussion in 2017

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.