Alert archive / Georgia / Mesoscale Discussions in 2017

Mesoscale Discussion 1801

December 20, 2017Chambers County, Lee County, Macon County, Alabama; 16 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2017, 11:46 AM CST for Chambers County, Lee County, Macon County, Alabama; 16 counties in Georgia. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued
Dec 20, 2017, 11:46 AM CST (17:46 UTC)
Expired
Dec 20, 2017, 1:45 PM CST
In force
119 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Chambers County, AL, Lee County, AL, Macon County, AL, Butts County, GA, Coweta County, GA, Fayette County, GA, Harris County, GA, Henry County, GA, Jasper County, GA, Jones County, GA, Lamar County, GA, Meriwether County, GA, Monroe County, GA, Muscogee County, GA, Pike County, GA, Spalding County, GA, Talbot County, GA, Troup County, GA, Upson County, GA

The radar

The Atlanta radar (KFFC), 64 km from the middle of the area, began a volume at 17:48 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

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 5.8 hours before the alert went out and 68 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, Peachtre/Fal Fld, GA at 12:00Z on 2017-12-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 11 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, Peachtre/Fal Fld, GA at 12:00Z on 2017-12-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 242 square meters per square second.1939587897Sfc1 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
11 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
572 m above ground
0-6 km bulk shear
76 kt
0-1 km storm-relative helicity
242 m²/s²
0-3 km storm-relative helicity
276 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

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Nearby

Mesoscale Discussions in Georgia, 2017Mesoscale Discussions in Alabama, 2017Every 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.