Special Weather Statement, NWS Nashville, TN

Area Forecast Discussion
National Weather Service Nashville TN
912 PM CDT Tue Mar 30 2021

.UPDATE...
FOR EVENING DISCUSSION.

&&

.DISCUSSION...

Showers continue to develop to our west as a surface frontal
boundary lifts northward. Evening balloon here at the office
highlighted PWAT values of 1.12", little instability, and shear
values around 20-30kts. In terms of severe weather potential, the
better dynamics appears to be south of I-40 closer to the AL/TN
border and our southwestern counties where some instability could
creep in overnight behind the warm front. Can't rule out damaging
wind gusts or an isolated tornado, but the overall threat appears
to be low. Our main concern heading into the rest of the evening
is the flash flooding potential. PWAT values are already up to
1.2" with values as high as 1.6" closer to Memphis. Latest MRMS
data from West TN has some rainfall rates of 1" per hour, which
would be concerning for our area. Our FFG is very low given our
saturated grounds and it will not take a lot to overwhelm some
local creeks and streams. Heaviest band of showers will likely
enter our NW counties in the next few hours, reach downtown just
after midnight, and move towards the Plateau by early morning.
Latest CAMs guidance has all of Middle TN receiving 1+" with some
areas seeing amounts closer to 2-3". 2-3" would be especially
concerning if the heaviest rain bands line up over the swath that
saw the most rainfall over the weekend. Flash Flood Watch remains
in effect as flash flooding is looking increasingly likely
overnight. Heaviest showers will exit the area by mid- morning as
our cold front will help move things out swiftly. Could see some
lingering showers in the afternoon, but overall the majority of
our heavy rainfall will fall overnight.

&&

.AVIATION...
00Z TAF DISCUSSION.

Expect decreased flight categories through the TAF period as a
line of showers/t'storms (some heavy at times) moves from west to
east through the area. Expect for cigs to begin dropping by 04Z at
CKV, 06Z for BNA/MQY, and 09Z for CSV associated with periods of
SHRA and TSRA. Heaviest downpours could lead to periods of IFR to
LIFR vis.

Gusty southerly winds will begin to become northerly across the
area between 08Z and 14Z beginning with CKV and ending with CSV.
Sustained winds in the 10-15kt range with gusts upwards of
15-25kts are expected.

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Wednesday morning for Bedford-Cannon-
Cheatham-Clay-Coffee-Cumberland-Davidson-De Kalb-Dickson-
Fentress-Giles-Grundy-Hickman-Houston-Humphreys-Jackson-Lawrence-
Lewis-Macon-Marshall-Maury-Montgomery-Overton-Perry-Pickett-
Putnam-Robertson-Rutherford-Smith-Stewart-Sumner-Trousdale-Van
Buren-Warren-Wayne-White-Williamson-Wilson.

&&

DISCUSSION......Adcock
AVIATION........Adcock

Hazardous Weather Outlook
National Weather Service Nashville TN
506 AM CDT Tue Mar 30 2021

TNZ005>011-023>034-056>066-075-077>080-093>095-311015-
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-
506 AM CDT Tue Mar 30 2021

This Hazardous Weather Outlook is for Middle Tennessee.

.DAY ONE...Today and tonight.

Flooding along many rivers and streams is ongoing as a result of
weekend rainfall event.

Some strong to severe thunderstorms may be possible for locations
approaching central and western portions of Tennessee River Valley
Region tonight. Main concern will be damaging winds.

A flash flood watch is in effect for all of middle Tennessee starting
this evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Several river and stream levels will remain elevated through at
least midweek, some continuing through Sunday...with some warnings
and advisories continuing also.

Some strong to severe thunderstorms may be possible for locations
approaching central and western portions of Tennessee River Valley
Region through early Wednesday morning. Main concern will be
damaging winds.

A flash flood watch is in effect for all of Middle Tennessee through
Wednesday evening. With already significant saturated ground
conditions, 1 to 2 inches...with locally higher amounts around 3
inches...of rainfall possible. Rainfall will cause excess runoff and
localized flash flooding, including adding additional water level
rises on already elevated area rivers and creeks.

It is expected to turn colder late week with several frosty nights.
A widespread freeze is expected Thursday night.

.SPOTTER INFORMATION STATEMENT...

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

12

Special Weather Statement
National Weather Service Nashville TN
1104 PM CDT Tue Mar 30 2021

TNZ006-023>026-056-057-059-310445-
Hickman TN-Williamson TN-Dickson TN-Humphreys TN-Cheatham TN-
Montgomery TN-Houston TN-Perry TN-
1104 PM CDT Tue Mar 30 2021

...SIGNIFICANT WEATHER ADVISORY FOR DICKSON...SOUTHEASTERN
MONTGOMERY...NORTHWESTERN WILLIAMSON...CENTRAL CHEATHAM...
SOUTHEASTERN HOUSTON...NORTH CENTRAL PERRY...HUMPHREYS AND NORTHERN
HICKMAN COUNTIES UNTIL 1145 PM CDT...

At 1103 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Tennessee Ridge to near McEwen to 7 miles
south of Hurricane Mills. Movement was east at 50 mph.

Winds in excess of 40 mph will be possible with these storms.

Locations impacted include...
Dickson, Ashland City, Waverly, Centerville, White Bluff, Kingston
Springs, Pegram, McEwen, Burns, Hurricane Mills, Fairview, Charlotte,
Vanleer, Slayden, Bon Aqua, Cheatham Dam, Lyles, Bucksnort, Pinewood
and Nunnelly.

This includes the following highways...
 Interstate 40 between mile markers 140 and 189.
 Interstate 840 between mile markers 1 and 11.

LAT...LON 3646 8723 3623 8702 3588 8714 3578 8789
      3606 8780 3625 8781
TIME...MOT...LOC 0403Z 257DEG 43KT 3625 8782 3609 8768 3587 8780

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