Special Weather Statement, NWS Nashville, TN

Area Forecast Discussion
National Weather Service Nashville TN
241 PM CDT Sun Jul 23 2017

.DISCUSSION...

Another hot and humid afternoon is underway across Middle Tennessee.
Throughout the morning and early afternoon hours, a couple of
outflow boundaries and weak shortwaves have traversed the mid-state
providing just enough lift to spark showers and a few thunderstorms.
Nothing has been particularly strong, but the combination of rain
and additional cloud cover has been enough to keep us from reaching
into the mid to upper 90s this afternoon.  Heat Index values have
still reached triple digits in many places and with the heavier,
more widespread rains not expected until the evening hours, the Heat
Advisory is still warranted, so we will allow to to run its course
and expire at 7 pm this evening.

Regarding those upcoming evening storms, another stronger impulse is
still expected to drop southward and spark more widespread activity
after 6 pm this evening.  There will still be plenty of instability
to fuel convection, however, with the lack of shear, no organization
is expected. This means clusters of thunderstorms will develop
and push slowly southward across the area. The slow movement will
provide moderate to heavy rainfall and an outside shot at some
decent gusty winds. The bulk of the convection should begin to
wane by 10 or 11 pm as we lose the heating of the day.

Monday through Wednesday should be relatively quiet.  Some afternoon
storms are possible Monday afternoon closer to the Alabama state
line as this will be where the best instability will reside.  A
stray thunderstorm won't be out of the question Tuesday and
Wednesday afternoons.  Of greater importance to everyone will be the
afternoon highs, which are expected to fall back towards normal
values.  This means low 90s and with dew points expected to remain
in the low 70s, it will still be hot and humid, but we should remain
below Heat Advisory criteria.

By late Thursday afternoon, under an admittedly unpredictable
northwesterly flow, models are depicting the approaching of a mid-
level disturbance that will bring showers and thunderstorms into the
region.  This activity is expected to linger into the overnight
hours Thursday and most likely into Friday.  Forecast soundings
during this time frame suggest a little more shear with which to
work, so some of these storms could become strong, especially
Friday afternoon as the bulk of the energy approaches Middle
Tennessee. Due to the northwesterly flow (and some model to model
inconsistencies in timing), I'll refrain from adding in any
strong wording to the Hazardous Weather Outlook for now, however,
it may need to be added in subsequent forecasts.

If there's good news in today's forecast package, it's that models
are progging cooler temperatures next weekend. While the Euro
holds onto rain into Saturday, Friday through Sunday's high
temperatures look below normal.

&&

.AVIATION...
18Z TAF DISCUSSION.

Upper level impulse will approach from the northwest by late this
afternoon. pva enhancement over the middle TN area will lead to an
increase in shower and tstm activity by 00z. Will include vcts
and prob 30's to cover the convection. Activity not quite expected
to be widespread enough to warrant tempo. Rainfall chances will
diminish after 06z with fog vsbys dropping to as low as 3-5sm
late. Look for partial haze during the 12z-18z timeframe.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      75  91  74  91  73 /  50  20  10  10  10
Clarksville    73  89  72  89  71 /  40  20  10  10  10
Crossville     69  84  69  84  67 /  60  20  10  20  10
Columbia       73  89  73  89  71 /  50  30  20  20  10
Lawrenceburg   73  88  72  89  71 /  50  40  20  20  20
Waverly        73  89  72  90  72 /  50  20  10  20  10

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT this evening FOR Bedford-Cheatham-
Davidson-Dickson-Giles-Hickman-Houston-Humphreys-Lawrence-Lewis-
Macon-Marshall-Maury-Montgomery-Perry-Robertson-Rutherford-Smith-
Stewart-Sumner-Trousdale-Wayne-Williamson-Wilson.

&&

DISCUSSION......Unger
AVIATION........21

Hazardous Weather Outlook
National Weather Service Nashville TN
523 AM CDT Sun Jul 23 2017

TNZ005>011-023>034-056>066-075-077>080-093>095-241030-
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-
523 AM CDT Sun Jul 23 2017

This Hazardous Weather Outlook is for portions of Middle
Tennessee.

.DAY ONE...Today and Tonight

Hot weather will continue today...and a Heat Advisory remains in
effect for areas west of the Cumberland Plateau. Maximum afternoon
heat index values will range from 100 to 106 degrees. In addition,
scattered thunderstorms are expected to develop late today and
tonight, especially in areas north of Interstate 40 and east of
Interstate 65. A few of those storms could become strong to
severe, with damaging winds, hail and heavy downpours.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Scattered thunderstorms will continue on Monday, as a weak cold
front sags slowly into the Mid State. Most storms are expected to
be over southern and eastern sections, and few storms along the
northern Cumberland Plateau could become strong to severe, with
damaging winds, hail and heavy downpours.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

Special Weather Statement
National Weather Service Nashville TN
502 PM CDT SUN JUL 23 2017

TNZ009-029-232230-
Trousdale TN-Macon TN-
502 PM CDT SUN JUL 23 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN MACON AND TROUSDALE
COUNTIES UNTIL 530 PM CDT...

At 502 PM CDT, Doppler radar was tracking a strong thunderstorm over
Hartsville, moving southeast at 10 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Hartsville.

LAT...LON 3647 8595 3643 8598 3640 8598 3638 8605
      3633 8611 3629 8613 3633 8617 3632 8619
      3634 8621 3634 8622 3635 8623 3634 8624
      3637 8627 3651 8612
TIME...MOT...LOC 2202Z 313DEG 8KT 3639 8617

Shamburger