Alert archive / Tennessee / Flash Flood Watches in 2020

Flash Flood Watch 3, NWS Morristown, TN

February 12, 202023 counties in Tennessee; Lee County, Virginia; Cherokee County, Clay County, North Carolina

NWS Morristown, TN issued this flash flood watch at Feb 12, 2020, 3:03 AM EST for 23 counties in Tennessee; Lee County, Virginia; Cherokee County, Clay County, North Carolina. It took effect at Feb 12, 2020, 7:00 PM EST. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued
Feb 12, 2020, 3:03 AM EST (08:03 UTC)
In effect from
Feb 12, 2020, 7:00 PM EST
Expired
Feb 13, 2020, 10:00 AM EST
In force
15 hr
Issued by
NWS Morristown, TN
Flood severity
None
All 26 counties

Cherokee County, NC, Clay County, NC, Anderson County, TN, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Campbell County, TN, Claiborne County, TN, Grainger County, TN, Hamilton County, TN, Hancock County, TN, Knox County, TN, Loudon County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Morgan County, TN, Polk County, TN, Rhea County, TN, Roane County, TN, Scott County, TN, Sequatchie County, TN, Sevier County, TN, Union County, TN, Lee County, VA

The radar

The Knoxville radar (KMRX), 93 km from the middle of the area, began a volume at 08:02 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 00:00Z, 8.1 hours before the alert went out and 268 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 00:00Z on 2020-02-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 39 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 00:00Z on 2020-02-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 12 square meters per square second.1939587897117Sfc1 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
39 J/kg
Mixed-layer CIN
-26 J/kg
Mixed-layer LCL
814 m above ground
0-6 km bulk shear
74 kt
0-1 km storm-relative helicity
12 m²/s²
0-3 km storm-relative helicity
222 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 flash flood watch went out at Feb 12, 12:36 AM EST, 2 hours 27 minutes earlier.

Area forecast discussion, Feb 12, 12:36 AM EST, 2 hours 27 minutes before
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Hazardous weather outlook, Feb 11, 2:52 PM EST, 12 hours 11 minutes before
Hazardous Weather Outlook...UPDATED
National Weather Service Morristown TN
252 PM EST Tue Feb 11 2020

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-121000-
Cherokee-Clay-Scott-Campbell-Claiborne-Hancock-Hawkins-Sullivan-
Johnson-Morgan-Anderson-Union-Grainger-Hamblen-Northwest Cocke-
Cocke Smoky Mountains-Northwest Greene-Southeast Greene-
Washington-Unicoi-Northwest Carter-Southeast Carter-Roane-Loudon-
Knox-Jefferson-Northwest Blount-Blount Smoky Mountains-
North Sevier-Sevier Smoky Mountains-Sequatchie-Bledsoe-Rhea-Meigs-
McMinn-Northwest Monroe-Southeast Monroe-Marion-Hamilton-Bradley-
West Polk-East Polk-Lee-Wise-Russell-
252 PM EST Tue Feb 11 2020 /152 PM CST Tue Feb 11 2020/

This Hazardous Weather Outlook is for portions of southwest North
Carolina...east Tennessee and southwest Virginia.

.DAY ONE...Tonight

No hazardous weather is expected.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Another storm system will approach the Tennessee valley and
southern Appalachians Wednesday and Wednesday night. This system
will strength the winds across the area with southerly winds
increasing to 25 to 40 mph with gusts up to 70 mph possible late
Wednesday through early Thursday morning.

A line of showers will cross the area Wednesday night into early
Thursday morning. Locally heavy rainfall may be possible. Strong
to marginally severe thunderstorms may also be possible in the
southern Tennessee Valley, with the potential for isolated
damaging wind gusts.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.

Nearby

Flash Flood Watches in Tennessee, 2020Flash Flood Watches in North Carolina, 2020Flash Flood Watches in Virginia, 2020Every flash flood watch 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.