Alert archive / Tennessee / Mesoscale Discussions in 2018

Mesoscale Discussion 1496

September 24, 2018Limestone County, Madison County, Alabama; 22 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Sep 24, 2018, 3:54 PM CDT for Limestone County, Madison County, Alabama; 22 counties in Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 24, 2018, 3:54 PM CDT (20:54 UTC)
Expired
Sep 24, 2018, 6:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
5%
All 24 counties

Limestone County, AL, Madison County, AL, Bedford County, TN, Cannon County, TN, Clay County, TN, Coffee County, TN, DeKalb County, TN, Franklin County, TN, Giles County, TN, Grundy County, TN, Jackson County, TN, Lincoln County, TN, Macon County, TN, Marshall County, TN, Moore County, TN, Overton County, TN, Putnam County, TN, Rutherford County, TN, Smith County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, White County, TN, Wilson County, TN

The radar

The Northeast Alabama radar (KHTX), 64 km from the middle of the area, began a volume at 20:54 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

Nashville Metro, TN (KBNA), launched 12:00Z, 8.9 hours before the alert went out and 79 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, Nashville Metro, TN at 12:00Z on 2018-09-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 58 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, Nashville Metro, TN at 12:00Z on 2018-09-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 105 square meters per square second.1939Sfc1 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
58 J/kg
Mixed-layer CIN
-57 J/kg
Mixed-layer LCL
821 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
105 m²/s²
0-3 km storm-relative helicity
220 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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Nearby

Mesoscale Discussions in Tennessee, 2018Mesoscale Discussions in Alabama, 2018Every mesoscale discussion in 2018

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.