Alert archive / Tennessee / Frost Advisories in 2020

Frost Advisory 6, NWS Morristown, TN

April 21, 202015 counties in Tennessee; 7 counties in Virginia; Cherokee County, Clay County, North Carolina

NWS Morristown, TN issued this frost advisory at Apr 21, 2020, 3:21 AM EDT for 15 counties in Tennessee; 7 counties in Virginia; Cherokee County, Clay County, North Carolina. It took effect at Apr 22, 2020, 5:00 AM EDT. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued: Apr 21, 2020, 3:21 AM EDT (07:21 UTC)
In effect from: Apr 22, 2020, 5:00 AM EDT
Expired: Apr 22, 2020, 10:00 AM EDT
In force: 5 hr
Issued by: NWS Morristown, TN

All 24 counties

Cherokee County, NC, Clay County, NC, Blount County, TN, Campbell County, TN, Carter County, TN, Claiborne County, TN, Cocke County, TN, Greene County, TN, Hancock County, TN, Hawkins County, TN, Johnson County, TN, Monroe County, TN, Scott County, TN, Sevier County, TN, Sullivan County, TN, Unicoi County, TN, Washington County, TN, City of Bristol, VA, City of Norton, VA, Lee County, VA, Russell County, VA, Scott County, VA, Washington County, VA, Wise County, VA

The radar

The Knoxville radar (KMRX), 37 km from the middle of the area, began a volume at 07:23 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 nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 00:00Z, 7.4 hours before the alert went out and 281 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: 1468 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 112 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this frost advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Morristown, TN wrote its last area forecast discussion before this frost advisory went out at Apr 21, 3:01 AM EDT, 20 minutes earlier.

Area forecast discussion, Apr 21, 3:01 AM EDT, 20 minutes before

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The office that day

Everything else NWS Morristown, TN issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 21, 2:35 AM EDT	Wind Advisory	MRX	Carter, Johnson, Unicoi	19 hr

Nearby

Frost Advisories in Tennessee, 2020 Frost Advisories in Virginia, 2020 Frost Advisories in North Carolina, 2020 Every frost advisory 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.