Forecast Discussion from NWS Nashville

Passing this along because it is unusually well-written, which is not surprising once you see the forecaster's name at the bottom, actually the lady who is Meteorologist-In-Charge of that office now. If you live on the Tennessee side of this event, definitely worth reading. 

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FXUS64 KOHX 081130

AFDOHX

Area Forecast Discussion

National Weather Service Nashville TN

630 AM CDT Wed May 8 2024

...New AVIATION...

.SHORT TERM...

(Today through Thursday)

Issued at 125 AM CDT Wed May 8 2024

All eyes are on today`s forecast as all modes of severe weather

including flash flooding are anticipated across Middle

Tennessee. I`ll be honest, things are very complex and not clear

cut, so it`s imperative for everyone to be weather aware all day

today into tonight. This is not a "one and done" type of event.

Multiple thunderstorms at multiple parts of the day will have the

opportunity to be severe. If you are going to be out and about

today and tonight, it`s imperative for you to check the weather

before heading out and have multiple ways to get notified when

warnings are issued.

Here`s what we`re confident on:

1) The potential for flash flooding has been increasing with each

model run and even though we didn`t get much in the way of

rainfall on Tuesday, this system has the unfortunate opportunity

to place a boundary over Middle Tennessee where ample moisture

will allow thunderstorms to train over the same locations over and

over and over. This boundary will likely set up near or north of

I-40, but there`s even a possibility that it sets up in Southern

Kentucky (and Middle Tennessee skirts away from the highest

precipitation totals). But wherever that boundary sets up, heavy

rainfall and flash flooding will result.

2) There will be some impressive straight line winds along with

some potential QLCS tornadoes when the main/final line of storms

pushes through late tonight. There`s definitely much more

uncertainty on how things unfold before this main line. Timing

things during the daylight hours is extremely difficult, but the

main line should move through after dark.

3) Lapse rates are also high so think any storm that develops

today through tonight will have the potential to produce large

hail.

4) Don`t be fooled by any morning or early afternoon convection

being "the event" or limiting things. The main line coming through

tonight will pack quite the punch that won`t care if you did or

didn`t have storms earlier in the day.

Here`s what we`re not confident on:

1) Speaking of the boundary, exactly where this will set up will

be the million dollar question. Short range models are having a

difficult time initializing correctly over our area during this

overnight period, so confidence on how everything will exactly

play out today is not very high. Regardless, all the parameters

you always hear meteorologists spout off during big severe weather

events are all there with ample moisture, instability, and shear.

2) If discrete supercells can develop this afternoon and evening,

this would spell big trouble for the tornado threat and increase

the severe weather potential significantly. Think this concern is

mostly for the northern half of Middle Tennessee but once again,

it all depends on where exactly the above mentioned boundary sets

up.

It`s Spring in Middle Tennessee. We want you to be prepared and

not scared. Today and tonight is when we need you to pay attention

to the weather as things will be rapidly evolving throughout the

day.

By Thursday morning, storms rapidly move south of Tennessee giving

way to drier conditions and partly cloudy skies.

&&

.LONG TERM...

(Thursday Night through next Wednesday)

Issued at 125 AM CDT Wed May 8 2024

Friday and this weekend look fairly nice weather wise as Highs in

the 70s and Lows in the 40s and 50s will be the main weather

story. There will be some northwest flow aloft and some model solutions

do have some weak upper level impulses swinging through the area.

Kept things dry for now, but would not be surprised to see some

increases in cloud cover and possible showers.

Another upper level trough will impact the area on Monday and

Tuesday as return flow brings the southerly flow and moisture

back. Showers and thunderstorms will return to the forecast, but

nothing looks impactful at this time.

&&

.AVIATION...

(12Z TAFS)

Issued at 626 AM CDT Wed May 8 2024

Messy aviation forecast today with TSRA in the area through much

of the current TAF period. Current line of TSRA will likely begin

to stall around the I-40 corridor, so some vis impacts as that

line progresses. Rest of the day will have scattered TSRA, with

periods of low cigs/vis. Final line of TSRA will move through

around to after 03Z from NW to SE, with conditions beginning to

improve near to after the current TAF period. Winds will remain

predominately from the south.

&&

.PRELIMINARY POINT TEMPS/POPS...

Nashville      84  69  84  58 /  90  90  30  10

Clarksville    82  68  82  55 /  90  90  10  10

Crossville     79  63  78  53 /  90  80  60  20

Columbia       85  66  85  55 /  80  90  40  10

Cookeville     80  65  80  54 /  90  90  50  10

Jamestown      80  63  78  53 /  90  90  50  20

Lawrenceburg   84  66  84  56 /  70  90  40  20

Murfreesboro   85  66  84  55 /  90  80  40  10

Waverly        82  65  83  55 /  90  90  20  10

&&

.OHX WATCHES/WARNINGS/ADVISORIES...

Flood Watch through Thursday morning for Bedford-Cannon-Cheatham-

Clay-Coffee-Cumberland-Davidson-De Kalb-Dickson-Fentress-Grundy-

Hickman-Houston-Humphreys-Jackson-Lewis-Macon-Marshall-Maury-

Montgomery-Overton-Perry-Pickett-Putnam-Robertson-Rutherford-

Smith-Stewart-Sumner-Trousdale-Van Buren-Warren-White-Williamson-

Wilson.

&&

$$

SHORT TERM...Hurley

LONG TERM....Hurley

AVIATION.....Adcock