378
FXUS64 KOHX 121150
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
650 AM CDT Wed Mar 12 2025

...New UPDATE, FIRE WEATHER...

.KEY MESSAGES...
Updated at 642 AM CDT Wed Mar 12 2025

- Scattered showers and thunderstorms (30 to 60 percent chance)
  late Wednesday night and Thursday with no severe storms
  anticipated.

- Severe thunderstorms possible at times Friday night through
  Saturday night. This includes potential for tornadoes, damaging
  straight line winds and large hail. Details are very uncertain
  at this time.

- Heavy downpours will occur and very breezy conditions are
  expected Friday night through Saturday night.

&&

.UPDATE...
Issued at 642 AM CDT Wed Mar 12 2025

The new day 3 convective outlook from the SPC brings an enhanced
risk area all the way to Nashville. So more or less all of Middle
Tennessee west of I-65 is under an enhanced risk of severe storms
Friday night. At this time, the primary impacts look to be
damaging straight-line winds, and a few tornadoes are also
possible. There is a lesser risk in other parts of Middle
Tennessee. Confidence in severe storm development Friday night is
medium. However, confidence is low in determining specific timing
of severe storms. There is also a risk of severe storms Saturday
and Saturday night, mainly in areas south of I-40. Details such
as timing and specific threats are still unclear for Saturday and
Saturday night.

&&

.SHORT TERM...
(Tonight through Thursday Night)
Issued at 1055 PM CDT Tue Mar 11 2025

Very dry high pressure will remain in control across the southern
states through Wednesday. We will be in store for another warm,
spring-like day with highs again well into the 70s with some spots
possibly topping 80.

Late in the day, a compact upper level trough will produce stormy wx
with a slight risk for severe storms over the ArkLaTex. This system
will weaken as it moves our way Wednesday night and Thursday.
Although we do not expect severe storms here, there will be
showers with some rumbles of thunder. Mid level lapse rates may
be just enough, combined with a few hundred J/kg cape and fairly
low wet bulb zero levels to produce small hail in a couple of the
scattered cells Thursday.

&&

.LONG TERM...
(Friday through next Wednesday)
Issued at 1030 PM CDT Tue Mar 11 2025

After Thursday`s upper low departs, our attention will immediately
turn to a much more substantial system expected to bring major
impacts all along the MS Valley to the OH/TN Valleys down to the
Gulf Coast. All modes of severe wx will be possible across a wide
area from late Friday through Saturday and into Saturday night.

The upper level system will come out of the Rockies Friday, spinning
up a deep surface low pressure and cold front over the Central
Plains. An expansive warm sector will be established downstream,
generally along the Mississippi Valley, where a robust southerly low-
level jet will advect warm, moist air from the Gulf. Thunderstorms
are expected to fire up along and east of the advancing front
along the Ms Valley, and this activity will reach Middle TN Friday
night into Saturday morning. It is uncertain how these storms
will behave as they move into our area. Conditions will not be
that impressive early in the evening, but the approaching line
combined with a 60KT LLJ could change the situation pretty
quickly. A surge of 500 J/kg MLCAPE and rapidly increasing deep
layer shear could maintain or bring new development of storms
including some supercells late Friday night. This is of greatest
concern for areas west of I-65.

Uncertainties abound as we go later into Friday night and on through
Saturday. A southern stream shortwave will come in from the west,
interacting with the large scale storm system, spinning up a
secondary low over our area. This rapidly evolving system with
several "moving parts" will make specifics of thunderstorm strength
and evolution very complex and uncertain. However, some key
parameters will be in place for significant severe wx potential
through Saturday including potential tornadoes, damaging winds,
large hail, and torrential downpours. We will just have to see how
updated models refine things over the next few days and hopefully
we can get a better handle on how this situation will unfold. We
may see 2 main natches of storms, Friday night and Saturday
afternoon, but that may depend on where you are. The greatest
risk Friday night will be over the west half and the greatest
risk for Saturday could shift to the east half. But again, with
such a complex setup, the scenario we have discussed over the past
24 hours could change. Regarding rainfall, very heavy downpours
are expected at times. Latest models show 2 to 3 inches of rain
through the event, but just as we have discussed with the severe
storm forecasts, the exact timing and locations impacted by heavy
rain could change. Generally speaking, we are looking for
localized flash flooding and rises along small streams. The flood
threat along major rivers appears relatively low.

Looking ahead to early next week, the pattern looks dry and a
little cooler, nothing extreme.

&&

.AVIATION...
(12Z TAFS)
Issued at 607 AM CDT Wed Mar 12 2025

VFR conditions for the TAF period. Clear skies today with high to mid-
level clouds building in this evening into the overnight.
Southerly winds 5-10 knots.

&&

.FIRE WEATHER...
Issued at 642 AM CDT Wed Mar 12 2025

There is an elevated fire weather risk this afternoon across
Middle Tennessee for minimum RH values of 25-35% and surface wind
gusts of 10-15 mph. Owing to tomorrow`s rain chances and higher
dew points, the elevated risk will not extend beyond today.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      78  55  74  55 /   0  10  30   0
Clarksville    77  55  73  54 /   0  20  30   0
Crossville     72  48  69  50 /   0   0  20   0
Columbia       76  55  74  55 /   0  10  30   0
Cookeville     73  52  71  52 /   0   0  30   0
Jamestown      72  49  70  50 /   0   0  20   0
Lawrenceburg   76  55  72  55 /   0  10  40  10
Murfreesboro   76  53  74  53 /   0  10  30   0
Waverly        76  56  73  55 /   0  20  30   0

&&

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

$$

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