788
FXUS64 KOHX 250105
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
805 PM CDT Tue Sep 24 2024

...New UPDATE...

.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...
(00Z TAFS)
Issued at 624 PM CDT Tue Sep 24 2024

Showers and a thunderstorm could impact BNA/MQY/CSV/SRB through
the evening hours before rain chances decrease. Models show MVFR,
possibly IFR stratus developing behind a weak front that will move
through the terminals overnight. Showers will lift from the south
and should impact SRB/CSV near dawn and continue off and on
through the rest of the forecast period. The shower activity will
likely reach BNA/MQY during the afternoon. CKV will remain dry
for the taf period. Winds overnight and through the day on
Wednesday are expected to be 5 kts or less.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      67  80  64  78 /  60  50  40  90
Clarksville    62  79  59  78 /  30  30  30  80
Crossville     61  72  57  70 /  80  80  70 100
Columbia       65  79  59  75 /  60  40  40  90
Cookeville     64  73  60  72 /  70  60  60 100
Jamestown      62  73  59  71 /  80  70  70 100
Lawrenceburg   65  78  59  74 /  60  50  50  90
Murfreesboro   65  79  61  76 /  60  50  50 100
Waverly        62  78  58  77 /  30  30  30  80

&&

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

$$

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