Alert archive / Tennessee / Areal Flood Advisories in 2021

Areal Flood Advisory 182, NWS Nashville, TN

October 6, 2021Coffee County, Grundy County, Warren County, Tennessee

NWS Nashville, TN issued this areal flood advisory at Oct 6, 2021, 9:15 PM CDT for Coffee County, Grundy County, Warren County, Tennessee. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
Oct 6, 2021, 9:15 PM CDT (02:15 UTC)
Expired
Oct 7, 2021, 12:15 AM CDT
In force
3 hr
Issued by
NWS Nashville, TN
Area
Storm-based polygon

Counties Coffee County, TN, Grundy County, TN, Warren County, TN

The radar

The Northeast Alabama radar (KHTX), 69 km from the middle of the area, began a volume at 02:16 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 00:00Z, 2.3 hours before the alert went out and 95 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 00:00Z on 2021-10-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 595 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 00:00Z on 2021-10-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 81 square meters per square second.19395878Sfc1 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
595 J/kg
Mixed-layer CIN
-52 J/kg
Mixed-layer LCL
871 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
81 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.2
Supercell composite
2.7

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Nashville, TN wrote its last area forecast discussion before this areal flood advisory went out at Oct 6, 6:10 PM CDT, 3 hours 5 minutes earlier.

Area forecast discussion, Oct 6, 6:10 PM CDT, 3 hours 5 minutes before
Area Forecast Discussion
National Weather Service Nashville TN
610 PM CDT Wed Oct 6 2021

.UPDATE...
FOR 00Z AVIATION DISCUSSION.

&&

.DISCUSSION...

Airmass continues to destabilize this afternoon. Southeast areas
were recently upgraded to a slight risk and we have seen a few
rotating cells on radar. Strongest storm is now in northwestern
Cumberland Co but appears to be remaining below severe limits at
this time. No wind or svr wx reports thus far.

On the other side of the coin is the flood threat. Moisture axis now
set up across the Plateau where appreciable amounts have occurred,
particularly across portions of the southern plateau. We are
expecting a stronger impulse to gain strength by this evening across
northeastern AL. Energy will transfer northward across eastern
portions of the mid state with another round of heavier showers and
thunderstorms. It looks as though the bulk of the rainfall will
occur this evening with the heaviest amounts to the east of I-65.
Note however, Lawrence county was ambushed with upwards of 5 inches
of rainfall yesterday. Will therefore keep the Flash flood watch
going for all the current counties. There was some contemplation in
regard to pulling the watch for our westernmost counties. However,
given the heavier rainfall that fell prior, along with the very low
ffg values, will opt to keep the watch in tact. The watch will
remain in effect through Thursday morning. Otw, look for overnight
rainfall amounts to range from a quarter inch west to up to 1 1/2
inches along the Plateau. Pops tonight will range from 50% west to
likely to categorical along the Plateau.

Moving on, the upper low will be lifting off to the north on
Thursday with drier air moving in. Rainfall chances will decrease
down to just a 20-30 percent chance by Thursday evening.

For the near term temps, looking warmer than normal, especially with
low temps which will run a good 10 to 15 degree above normal.

In the ext fcst, upper ridging still expected to build into the
region through the weekend. A weakening frontal boundary will bring
both a brief and low percentage chance of showers for early next
week. Otw, its looking quite warm with elevated heights and warm
850 mb temps. Look for highs to hold in the 80s with lows in the
lower to mid 60s. That equates to about 12 to 15 degrees above
normal.

&&

.AVIATION...
00Z TAF DISCUSSION.

Upper level impulse will work northward this evening across
primarily the eastern half of the mid state. Airmass is rather
unstable and strong to severe storm potential will remain for CSV
through 03Z. Aft 03Z, showers to continue through at least 08Z to
10Z. Elsewhere, western and central middle TN taf sites will lean
toward NSW aft 06Z. Across the east, convective coverage should
begin to decrease late tonight with this trend continuing into the
day on Thursday.

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday morning for Bedford-Coffee-
Cumberland-Giles-Grundy-Lawrence-Marshall-Van Buren-Warren-Wayne.

&&

DISCUSSION......21
AVIATION........21
Hazardous weather outlook, Oct 6, 5:01 AM CDT, 16 hours 14 minutes before
Hazardous Weather Outlook
National Weather Service Nashville TN
501 AM CDT Wed Oct 6 2021

TNZ005>011-023>034-056>066-075-077>080-093>095-071000-
Stewart-Montgomery-Robertson-Sumner-Macon-Clay-Pickett-Houston-
Humphreys-Dickson-Cheatham-Davidson-Wilson-Trousdale-Smith-Jackson-
Putnam-Overton-Fentress-Perry-Hickman-Lewis-Williamson-Maury-
Marshall-Rutherford-Cannon-De Kalb-White-Cumberland-Bedford-Coffee-
Warren-Grundy-Van Buren-Wayne-Lawrence-Giles-
501 AM CDT Wed Oct 6 2021

This Hazardous Weather Outlook is for Middle Tennessee.

.DAY ONE...Today and tonight.

A flash flood watch is in effect through tonight for southern
locations approaching Tennessee/Alabama Border Region and across
central and southern portions of Cumberland Plateau Region.
Rainfall amounts of one to three inches, with locally higher
amounts, will be possible.

Isolated strong to severe thunderstorms will be possible this
afternoon and evening across most of Middle Tennessee. With
any strong to severe thunderstorms that do develop, main threats
will be strong to damaging winds and potentially large hail.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Showers and scattered thunderstorms continuing across eastern
portions of mid state region could cause continuing flooding
concerns across this area through at least Thursday afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any
information about observed severe weather to the NWS
while following all local, state, and CDC guidelines.

JB Wright

In the hours before

Local storm report, Oct 6, 8:50 PM CDT, 25 minutes before
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Local storm report, Oct 6, 9:02 PM CDT, 13 minutes before
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Local storm report, Oct 6, 9:04 PM CDT, 11 minutes before
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Local storm report, Oct 6, 9:08 PM CDT, 7 minutes before
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Local storm report, Oct 6, 9:09 PM CDT, 6 minutes before
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Local storm report, Oct 6, 9:14 PM CDT, 1 minute before
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The office that day

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

IssuedProductOfficeCountiesLasted
Oct 6, 7:04 PM CDTSpecial Weather StatementOHXRutherford41 min
Oct 6, 7:11 PM CDTAreal Flood AdvisoryOHXCumberland, Fentress, Pickett3 hr
Oct 6, 7:12 PM CDTSevere Thunderstorm WarningOHXDickson, Hickman33 min
Oct 6, 7:14 PM CDTTornado WarningOHXFentress31 min
Oct 6, 7:16 PM CDTAreal Flood AdvisoryOHXPutnam, White3 hr
Oct 6, 7:22 PM CDTAreal Flood AdvisoryOHXDeKalb, Warren, White3 hr
Oct 6, 7:32 PM CDTAreal Flood AdvisoryOHXHumphreys, Perry3 hr
Oct 6, 7:44 PM CDTAreal Flood AdvisoryOHXBedford, Rutherford3 hr
Oct 6, 7:44 PM CDTSevere Thunderstorm WarningOHXFentress, Pickett26 min
Oct 6, 7:48 PM CDTFlash Flood WarningOHXGiles5 hr
Oct 6, 7:54 PM CDTSpecial Weather StatementOHXCoffee51 min
Oct 6, 8:07 PM CDTAreal Flood AdvisoryOHXDavidson, Maury, Williamson113 min
Oct 6, 8:17 PM CDTSpecial Weather StatementOHXHumphreys28 min
Oct 6, 8:28 PM CDTAreal Flood AdvisoryOHXHumphreys4 hr
Oct 6, 8:52 PM CDTFlash Flood WarningOHXCumberland, Fentress, Overton, Pickett, Putnam, White3 hr
Oct 6, 8:56 PM CDTFlash Flood WarningOHXHumphreys, Perry4 hr
Oct 6, 8:59 PM CDTFlash Flood WarningOHXPerry, Wayne4 hr
Oct 6, 10:24 PM CDTFlash Flood WarningOHXBedford3 hr
Oct 6, 10:40 PM CDTAreal Flood AdvisoryOHXHouston, Humphreys, Montgomery3 hr
Oct 6, 10:56 PM CDTAreal Flood AdvisoryOHXBedford, Cannon, Coffee, Rutherford3 hr
Oct 6, 10:57 PM CDTSpecial Weather StatementOHXCannon33 min
Oct 6, 11:35 PM CDTAreal Flood AdvisoryOHXCannon, DeKalb, Rutherford, Smith, Wilson3 hr
Oct 7, 12:24 AM CDTAreal Flood AdvisoryOHXDeKalb, Jackson, Putnam, Smith, Trousdale, Wilson2 hr
Oct 7, 1:45 AM CDTRiver Flood AdvisoryOHXBedford8 hr
Oct 7, 9:29 AM CDTRiver Flood AdvisoryOHXPerry20 hr

Nearby

Areal Flood Advisories in Tennessee, 2021Every areal flood advisory in 2021

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.