Alert archive / Alabama / Mesoscale Discussions in 2015

Mesoscale Discussion 1978

November 18, 20154 states

The Storm Prediction Center issued this mesoscale discussion at Nov 18, 2015, 5:21 AM CST for 4 states. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Nov 18, 2015, 5:21 AM CST (11:21 UTC)
Expired: Nov 18, 2015, 7:15 AM CST
In force: 114 min
Issued by: the Storm Prediction Center

All 23 counties

Baldwin County, AL, Choctaw County, AL, Clarke County, AL, Dallas County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Perry County, AL, Sumter County, AL, Tuscaloosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 116 km from the middle of the area, began a volume at 11:23 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.

Tornado Watch 552Nov 18, 8:25 AM CST

The nearest sounding before it

Jackson, MS (KJAN), launched 00:00Z, 11.4 hours before the alert went out and 201 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: 107 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 916 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 309 m²/s²
0-3 km storm-relative helicity: 502 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 18, 1:14 AM CST	Mesoscale Discussion	SPC	Choctaw, Clarke, Fayette, Greene, Hale, Lamar and 8 more	2 hr
Nov 18, 2:49 AM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Greene, Hale, Marengo and 4 more	6 hr
Nov 18, 7:22 AM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Bibb, Butler, Chilton, Clarke and 14 more	83 min
Nov 18, 8:25 AM CST	Tornado Watch	SPC	Autauga, Baldwin, Barbour, Bullock, Butler, Clarke and 22 more	8 hr
Nov 18, 10:51 AM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Barbour, Bullock, Butler, Coffee and 17 more	114 min
Nov 18, 1:39 PM CST	Mesoscale Discussion	SPC	Barbour, Coffee, Covington, Crenshaw, Dale, Geneva and 3 more	2 hr
Nov 18, 2:16 PM CST	Tornado Watch	SPC	Coffee, Dale, Geneva, Henry, Houston	6 hr
Nov 18, 5:35 PM CST	Mesoscale Discussion	SPC	Franklin, Gadsden, Gulf, Jefferson, Leon, Liberty and 1 more	115 min
Nov 17, 6:53 PM CST	Mesoscale Discussion	SPC	Concordia	97 min
Nov 17, 7:45 PM CST	Tornado Watch	SPC	Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberia and 25 more	7 hr
Nov 17, 11:11 PM CST	Mesoscale Discussion	SPC	Livingston, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington	94 min

Nearby

Mesoscale Discussions in Alabama, 2015 Mesoscale Discussions in Mississippi, 2015 Mesoscale Discussions in Louisiana, 2015 Every mesoscale discussion in 2015

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.