Alert archive / Texas / Mesoscale Discussions in 2020

Mesoscale Discussion 1845

December 13, 20206 parishes in Louisiana; 17 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 13, 2020, 1:46 PM CST for 6 parishes in Louisiana; 17 counties in Texas. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Dec 13, 2020, 1:46 PM CST (19:46 UTC)
Expired: Dec 13, 2020, 3:45 PM CST
In force: 119 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

All 23 counties

Acadia Parish, LA, Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Jefferson Davis Parish, LA, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Newton County, TX, Orange County, TX, Polk County, TX, San Jacinto County, TX, Tyler County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 12 km from the middle of the area, began a volume at 19:48 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

Lake Charles Mun, LA (KLCH), launched 12:00Z, 7.8 hours before the alert went out and 184 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 879 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 302 m²/s²
0-3 km storm-relative helicity: 387 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 13, 1:00 AM CST	Mesoscale Discussion	SPC	Hansford, Hemphill, Hutchinson, Lipscomb, Moore, Ochiltree and 2 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2020 Mesoscale Discussions in Louisiana, 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.