Special Weather Statement, NWS Nashville, TN

Area Forecast Discussion
National Weather Service Nashville TN
839 PM CDT Mon May 3 2021

.UPDATE...
FOR EVENING DISCUSSION.

&&

.DISCUSSION...

Upper level ridging influences strong enough to suppress
convective development has occurred this afternoon into these
early evening hours across mid state region keeping our area
dry and relatively cloud free. However weakening upper level
ridging influences anticipated by consensus model blends as mid
to late evening hours progress. What that will potentially bring,
if a forcing mechanism aloft like a shortwave passage in
developing southwesterly flow aloft occurs across mid state region,
is potential for rapid strong to severe thunderstorm development.
OHX 05/00Z sounding showing an atmosphere primed for strong
convection with sfc based CAPES well over 3,000 J/KG, LI -11, low
LCL/LFC heights, SFC-3 km SRH values around 220 M2/S2, and at
least in lower levels indication of a right turning hodograph,
with PW values approaching 1.4 inches. Latest HRRR model trends
are showing some bullseye of heavy rainfall amounts across mid
state region during overnight hours too and that trend will need
continued monitoring. Adjusted afternoon forecast to show
transition from a mostly clear with little vertical extent to
cumulus field environment early this evening to an environment
supportive of robust convective development mainly after midnight
tonight. Tweaked hourly temperature, dewpoint, wind speed, wind
direction, sky, and pop grids and blended them with previously
associated forecasted values. With continuance of strength of
southerly low level flow tonight, raised overnight low
temperatures on average by a couple of degrees across mid state
region. Remainder of forecast continues to be on track.

Again, the key player here is how long these strong enough upper
level ridging influences that having been suppress convective
development hang around mid state region this evening and
potentially into the overnight hours. If they actually hold
longer than consensus model blends advertise, development of
showers and thunderstorms may not occur as soon as previously
thought for the late evening through overnight time frame.
If these upper level ridging influences weaken more rapidly than
expected, strong convection could develop sooner than later.
Basically mid state continues to be in a wait and see mode as
these evening hours progress.

&&

.AVIATION...
00Z TAF DISCUSSION.

Currently have VFR conditions at all TAF sites. Developing VCTS
are possible after 02-03Z and continue intermittently through the
overnight hours. Will leave the CIGs VFR...but if a storm pops up
in or around a terminal CIGs and VISs could drop to IFR. Another
more definite round of showers and thunderstorms expected after
11Z which should bring MVFR conditions. There may be a break in
the late afternoon with a return to VFR after 18-20Z.

Wind will turn southerly and gust 15-20KT.

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

DISCUSSION......JB Wright
AVIATION........12

Hazardous Weather Outlook
National Weather Service Nashville TN
813 PM CDT Mon May 3 2021

TNZ005>011-023>034-056>066-075-077>080-093>095-041000-
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-
813 PM CDT Mon May 3 2021

This Hazardous Weather Outlook is for Middle Tennessee.

.DAY ONE...Tonight.

Some severe thunderstorms will be possible mainly after midnight
tonight across mid state region, especially northwest portions.
Main threats are damaging winds and large hail. Formation of a
tornado or two could also be possible, especially across northwest
portions. Brief heavy rainfall causing localized flooding will also
be possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Rounds of showers and thunderstorms are expected through the day
and into at least the evening hours Tuesday. Severe storms are
possible with all threats possible, including damaging winds,
large hail, isolated tornadoes, and brief heavy rainfall
resulting in localized flooding.

.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.

Spotter Thunderstorm Reporting Criteria...
Tornado
Funnel Cloud
Flooding
Hail >= 1/2 Inch
Winds > 50 MPH(Measured)
Structural Damage
Trees or Power Lines Down

Special Weather Statement
National Weather Service Nashville TN
1150 PM CDT Mon May 3 2021

TNZ007-008-027-040530-
Robertson TN-Davidson TN-Sumner TN-
1150 PM CDT Mon May 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL DAVIDSON...WESTERN
SUMNER AND SOUTHEASTERN ROBERTSON COUNTIES UNTIL 1230 AM CDT...

At 1150 PM CDT, Doppler radar was tracking a strong thunderstorm near
Joelton, or 11 miles south of Springfield, moving northeast at 35
mph.

Half inch hail will be possible with this storm.

Locations impacted include...
Gallatin, Hendersonville, Goodlettsville, White House, Millersville,
Greenbrier, Ridgetop, Cross Plains, Portland, Joelton, Orlinda,
Mitchellville, Whites Creek and Cottontown.

This includes the following highways...
 Interstate 65 between mile markers 93 and 121.
 Interstate 24 between mile markers 32 and 43.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3646 8636 3623 8680 3634 8692 3635 8691
      3664 8658 3663 8656 3664 8655 3664 8654
      3665 8651 3665 8649
TIME...MOT...LOC 0450Z 231DEG 29KT 3634 8680

Schaper

Special Weather Statement
National Weather Service Nashville TN
1156 PM CDT Mon May 3 2021

TNZ008>010-028>031-040530-
Wilson TN-Trousdale TN-Sumner TN-Clay TN-Jackson TN-Macon TN-
Smith TN-
1156 PM CDT Mon May 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN SMITH...NORTHWESTERN
JACKSON...NORTHEASTERN SUMNER...NORTHEASTERN WILSON...NORTHWESTERN
CLAY...MACON AND TROUSDALE COUNTIES UNTIL 1230 AM CDT...

At 1155 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Westmoreland to 11 miles west of Lafayette
to near Hartsville to 10 miles northeast of Lebanon. Movement was
east at 35 mph.

Penny size hail will be possible with these storms.

Locations impacted include...
Lafayette, Gainesboro, Hartsville, Westmoreland, Red Boiling Springs,
Bethpage, Whitleyville, Dixon Springs, Oak Grove, Pleasant Shade,
Dickerson Chapel Recreation Area and Bugtussle.

LAT...LON 3662 8575 3657 8570 3647 8565 3630 8567
      3628 8630 3640 8630 3647 8633 3658 8640
      3664 8621
TIME...MOT...LOC 0455Z 259DEG 31KT 3652 8628 3648 8623 3640 8619 3632
8621

Schaper