Alert archive / Tennessee / Frost Advisories in 2018

Frost Advisory 3, NWS Morristown, TN

April 20, 201811 counties in Tennessee; 7 counties in Virginia

NWS Morristown, TN issued this frost advisory at Apr 20, 2018, 3:18 PM EDT for 11 counties in Tennessee; 7 counties in Virginia. It took effect at Apr 21, 2018, 4:00 AM EDT. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued: Apr 20, 2018, 3:18 PM EDT (19:18 UTC)
In effect from: Apr 21, 2018, 4:00 AM EDT
Expired: Apr 21, 2018, 9:00 AM EDT
In force: 5 hr
Issued by: NWS Morristown, TN

Counties Blount County, TN, Carter County, TN, Cocke County, TN, Greene County, TN, Hancock County, TN, Hawkins County, TN, Johnson 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), 72 km from the middle of the area, began a volume at 19:21 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

Roanoke, VA (KRNK), launched 12:00Z, 7.3 hours before the alert went out and 295 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: 1406 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: -19 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 19, 7:01 PM EDT, 20 hours 17 minutes earlier.

Area forecast discussion, Apr 19, 7:01 PM EDT, 20 hours 17 minutes before

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Nearby

Frost Advisories in Tennessee, 2018 Frost Advisories in Virginia, 2018 Every frost advisory 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.