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FXUS64 KOHX 211541 AAB
AFDOHX

Area Forecast Discussion...UPDATED
National Weather Service Nashville TN
1041 AM CDT Sat Aug 21 2021

.UPDATE...
FOR MORNING DISCUSSION.

.DISCUSSION...

Incredibly active flash flood situation ongoing for western
portions of Middle Tennessee this morning where 8 to 12 inches of
rain has been reported so far in locations in and around Houston,
Humphreys, Dickson, and Hickman Counties. Some of the rainfall
amounts that we`re seeing are a good 20%-25% of the TOTAL rainfall
amounts we see in a year around here. MRMS radar estimates show a
swath of 14 inches of rainfall with a few pixels of 17 inches.
Even though this is likely an overestimation, it`s still quite
impressive to see amounts that high since this morning. In the 4-5
years we`ve been using this radar rainfall estimation this
product, we think this is the highest we`ve seen it as it`s maxed
out the color scale.

There`s no wonder we were able to get incredible rainfall
rates/amounts this morning as the 12Z sounding from the office
recorded Precipitable Water (PW) value of 2.37 inches which is
well above the Daily Max of 2.21 inches for August 21st. The good
news is...rainfall rates and amounts are on the downward trend
finally which should help some of the hardest areas hit this
morning. Flood waters should begin receding here soon especially
those in Dickson and Houston Counties. However, still a
dire/catastrophic situation ongoing in Humphreys and Hickman
Counties!!! In addition, we are continuing to monitor the flash
flood threat for Maury, Perry, and Lewis Counties as another 1-3
inches of rain will be possible in these counties.

With that said, continued the Flash Flood Watch until 3pm. Off and
on thunderstorms will be possible outside of the Flash Flood
Watch too. Please stay tuned to any and all warnings and please
do not travel into these hard hit flooded counties if you do not
have to!

Outside of the flood threat, we are monitoring the potential for a
strong thunderstorm or two later this afternoon mainly across
Southern Middle Tennessee. Although this threat seems rather
secondary at the moment to the ongoing flash flooding. Stay safe
out there everyone and help us remind everyone Turn Around Don`t
Drown and Move to Higher Ground!

&&

.AVIATION...
12Z TAF DISCUSSION.

BNA/MQY/CKV/CSV...Messy set of TAF`s this morning. A surface
boundary has set up just west of Nashville and has provided the
focus for a band of excessive rainfall and is moving slowly
eastward. We`ll start the TAF`s with generally low ceilings and
visibilities owing to widespread showers, with TEMPO TSRA/CB`s for
the embedded convective cells. Rain should gradually lessen in
intensity and coverage during the next several hours while
ceilings improve, but the HRRR brings in another round of storms
later this afternoon.

.OHX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 3 PM CDT this afternoon for Bedford-
Cheatham-Dickson-Giles-Hickman-Houston-Humphreys-Lawrence-Lewis-
Marshall-Maury-Montgomery-Perry-Stewart-Wayne-Williamson.

$$

DISCUSSION......Hurley
AVIATION........08