Alert archive / Mississippi / Mesoscale Discussions in 2020

Mesoscale Discussion 1871

December 24, 20204 states

The Storm Prediction Center issued this mesoscale discussion at Dec 24, 2020, 1:02 AM CST for 4 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Dec 24, 2020, 1:02 AM CST (07:02 UTC)
Expired: Dec 24, 2020, 2:00 AM CST
In force: 58 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 40%

Counties Baldwin County, AL, Covington County, AL, Escambia County, AL, Mobile County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Saint Tammany Parish, LA, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Lamar County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 33 km from the middle of the area, began a volume at 07:03 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 517Dec 24, 1:40 AM CST

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 7.0 hours before the alert went out and 129 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: 29 J/kg
Mixed-layer CIN: -49 J/kg
Mixed-layer LCL: 705 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 273 m²/s²
0-3 km storm-relative helicity: 337 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Dec 24, 1:42 AM CST	Tornado Watch	SPC	Baldwin, Butler, Clarke, Conecuh, Covington, Crenshaw and 4 more	7 hr
Dec 24, 5:23 AM CST	Mesoscale Discussion	SPC	Bay, Gulf, Walton, Washington	2 hr
Dec 24, 12:11 PM CST	Mesoscale Discussion	SPC	Gadsden, Jefferson, Leon, Liberty, Madison, Taylor and 1 more	94 min
Dec 24, 3:28 PM CST	Mesoscale Discussion	SPC	Baker, Bradford, Clay, Columbia, Duval, Gilchrist and 5 more	92 min
Dec 23, 8:40 PM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 25 more	5 hr
Dec 23, 10:51 PM CST	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Cameron, East Baton Rouge, East Feliciana and 18 more	114 min

Nearby

Mesoscale Discussions in Mississippi, 2020 Mesoscale Discussions in Alabama, 2020 Mesoscale Discussions in Florida, 2020 Every mesoscale discussion in 2020

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.