824
FXUS64 KOHX 250546
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
1246 AM CDT Wed Sep 25 2024

...New AVIATION...

.UPDATE...
Issued at 750 PM CDT Tue Sep 24 2024

Scattered showers and storms are continuing to push across Middle
Tennessee with the last line extending from Perry County
northeastward to Robertson County. The trend of that line has been
downward over the last 30 minutes. IR satellite have shown a
general warming of cloud top over the last hour. The 00z OHX
sounding shows MUCAPE values still above 1000 J/kg but mlCAPE
around 500 J/kg which indicates that the low levels have been
fairly worked over. Some gusty winds may be possible with the
strongest cells over the next hour or two but I`m not expecting
anything severe. Shower and storm coverage will decrease as we
approach midnight. Some additional showers should begin to lift
into the area from the south late tonight into tomorrow as upper
level energy pivots around the upper low. The forecast is on track
and no major changes were made.

&&

.SHORT TERM...
(Rest of today through Wednesday)
Issued at 1114 AM CDT Tue Sep 24 2024

After parts of the area had morning showers and a few storms,
much of Middle Tennessee was experiencing a midday break. We do
expect showers and storms will build up again through the
afternoon and we continue to be under a marginal to slight risk
(level 1 to 2 out of 5) for severe storms with gusty winds.

Variably cloudy skies will allow for periods of sunshine and
heating into the 80s this afternoon. 1500-2000 J/kg ML cape still
looks on target today. The biggest differences from previous days
will be more forcing and much more shear. A couple of impulses
will precede an approaching surface front. Also, shear will
strengthen with 40KT deep layer shear and 500mb winds reaching
50KT. These factors will boost storm coverage and potential for
embedded damaging wind gusts. The tornado risk is very low, but
not zero.

Short range models seem to depict the general scenario well,
although exact timing and placement of main bands may be off.
Generally, bands of showers and storms will fire up this
afternoon with the main focus over our northwest counties starting just
after lunchtime. Then the focus will shift to Nashville Metro
southwest to Lawrenceburg area mainly 2 PM to 8 PM, then gradually
shifting east of I-65 into the evening from 6 PM to midnight.

The front moving in today will stall out tonight and Wednesday as
an upper level low pressure system cuts off just to our west.
This will keep showers and a few storms scattered across the area
tonight through Wednesday. The extra clouds and scattered rain
will limit Wednesday`s temps to the 70s for most areas. As shower
activity lessens in the nighttime hours, some partial clearing and
patchy fog will form.

&&

.LONG TERM...
(Wednesday Night through next Tuesday)
Issued at 1114 AM CDT Tue Sep 24 2024

Confidence continues to increase for soaking rainfall late this
week as the remnants of tropical system Helene impact the region.
The center of Helene is expected to move onshore Thursday evening
along the Florida Gulf Coast as a major hurricane. By that time,
heavy rain and gusty winds will have spread well north of the
center as the tropical moisture begins to interact with the
cutoff upper level low just to our west. The best time for
widespread and possibly heavy rainfall will be Thursday afternoon
through Friday morning. Although the heaviest rain with Helene is
expected to our east, Middle Tennessee is still in line for 2 to 3
inches of rain Thursday afternoon into Friday morning based on
the latest WPC QPF. The higher end amounts are expected over the
Plateau. Additional showers outside that time period could push
the late week event totals toward 4 or 5 inches. However, if the
track is farther east or the main swath of rain moves through
quickly, event totals could be lower. Model statistics give us at
least 80 percent chance for more than 1 inch late this week, so
we should be excited for some drought relief.

After the main swatch moves through by Friday afternoon, we will
have on and off scattered showers through the rest of the weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 1242 AM CDT Wed Sep 25 2024

A deep upper trough to our west continues to amplify and looks to
have some impact on the weather across Middle Tennessee for the
next several days. In the near-term, mainly light showers continue
to stream across the Cumberland Plateau as remnants of yesterday`s
active weather. We do expect some radiation fog and low ceilings
to develop toward morning, as well as re-development of more light
rain, but this will affect mainly the Cumberland Plateau and
adjacent areas, with less impact on the remainder of our
terminals.


&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      80  63  77  67 /  50  30  70  90
Clarksville    78  59  78  66 /  20  20  70  80
Crossville     71  57  69  60 /  80  60  90  90
Columbia       79  59  76  64 /  40  30  80  80
Cookeville     73  60  71  63 /  70  50  90  90
Jamestown      73  59  70  62 /  70  60  80  90
Lawrenceburg   78  59  75  63 /  50  30  80  90
Murfreesboro   78  61  76  65 /  60  40  80  90
Waverly        78  58  77  63 /  20  20  70  80

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE.......Reagan
SHORT TERM...13
LONG TERM....13
AVIATION.....Rose