textproduct: Nashville

KEY MESSAGES

Updated at 540 AM CST Thu Dec 26 2024

- Showers move in early tomorrow morning, increasing to storms on Saturday afternoon and evening. Rain totals could start piling up by Sunday morning with 2-4 inches possible Friday through Sunday.

- Strong storms look much less likely on Saturday, but can not be ruled out just yet.

- Minor flooding is becoming a possibility by Saturday night.

SHORT TERM

(Today) Issued at 153 AM CST Thu Dec 26 2024

As part of this current system we've been talking about for the last several days, very light rain is being shown on radar north of I-40 and west of I-65. When I say very, a hundredth of two is the extent this area will see. These light showers will move out before sunrise and set the stage for a mostly cloudy day with warm temperatures, but we should remain dry.

LONG TERM

(Tonight through next Thursday) Issued at 153 AM CST Thu Dec 26 2024

Today's dryness, however, will quickly vanish tonight. The first of two systems that will bring quite a bit of rain to the mid-state is due to arrive in our western zones shortly before sunrise Friday morning. This first system remains relatively benign. Showers will spread across Middle TN throughout the day. With the compact nature of these showers, Friday shouldn't be a washout for anyone. For example, those west of I-65 should be dry after the lunch hour and the Plateau should hold off until shortly before lunch. However, showers will probably linger into the early evening hours on the Plateau. Overall, this first system should bring 0.75 to 1.25 inches of rain to the mid-state. Completely acceptable rainfall numbers. The problem is, our second system will enter the area pretty quickly on the heels of the first.

After a lull in the activity Friday night, the second system of the weekend is progged to move into the mid-state Saturday afternoon. This is the one that could create some issues. First off, the severe threat: while not completely out of the picture, severe chances look low. While many severe weather parameters look to be in place, we're still carrying a sub-30% chance of reaching 300 J/Kg. I think to see any severe weather, we need to see north of that. However, with a medium or better chance of seeing at least a couple hundred J/Kg, convective storms will be possible. This means that, coupled with almost saturated forecast soundings and the potential for efficient rainfall processes to be in place, QPFs for this second system (and the weekend on the whole) continue to increase. Current 3-day totals, from Friday into Sunday morning are now running 2-4 inches, with the potential to see more. Why do I say this? There are at least a couple GEFS members showing upwards of 5 inches. While that makes for a small percentage of members, it's not completely out of the question to see QPFs come up some more in subsequent forecasts as deterministic solutions of the GFS and NAM are both now showing 4+ inch swaths occurring at least somewhere in Middle TN (obviously the exactly location of these is very much uncertain, but with the GFS showing a heavy swath in the same general vicinity the last couple of nights, it can't be completely ignored yet). Bottom line, we could be looking at least at some minor flooding come Saturday night.

New Year's Week is still looking quite uncertain as extended guidance remains in disagreement. However, these warmer-than- normal temperatures should vanish sometime next week as both models are showing cold air arriving in Middle TN by the middle to the end of the week.

AVIATION

(12Z TAFS) Issued at 540 AM CST Thu Dec 26 2024

Very light showers currently making their way through the western half of Middle TN shouldn't have any impacts on terminals. Dry conditions in store for the remainder of the day with light winds generally out of the southeast at all sites. Rain will approach CKV early Friday morning, bringing MVFR cigs with it. These lower cigs and precip may start to close in on BNA just before 12Z Friday. All other terminals can expect rain to hold off until after 12Z. BKN to OVC mid and high clouds to remain in place throughout the period.

PRELIMINARY POINT TEMPS/POPS

Nashville 60 48 60 54 / 10 50 100 70 Clarksville 58 48 61 54 / 10 90 100 70 Crossville 55 42 53 48 / 0 10 90 80 Columbia 57 47 59 54 / 10 60 100 60 Cookeville 58 45 56 52 / 0 20 90 80 Jamestown 57 42 55 49 / 10 20 90 80 Lawrenceburg 57 47 57 53 / 10 50 100 70 Murfreesboro 59 48 59 54 / 0 40 100 80 Waverly 57 47 60 54 / 10 90 100 70

OHX WATCHES/WARNINGS/ADVISORIES

None.