LONG TERM
(Sunday through Saturday)
Issued at 331 AM EDT Sat Jul 27 2024

Key Messages:

1. Showers and storms are expected each day with the best coverage on Monday and Tuesday. Localized flooding is possible Sunday through Tuesday, along with potentially stronger/more organized storms on Tuesday.

2. Hotter temperatures are expected mid to late week with less coverage of storms.

Sunday through Tuesday

At the start of the period, ridging will be centered over the area with a closed low off the Atlantic Coast and another centered near Missouri. Surface high pressure will also be just to our east.
Throughout the day, the closed low to our northwest will approach the area with the surface high gradually receding into the Atlantic.
In this pattern, broad southerly flow will advect moisture across most of the area with PWATs reaching around 2 inches, at or above the 90th percentile for this time of year. The increased moisture and height falls will support more scattered to widespread convection. The best coverage will be west of the central Valley in proximity to the greatest moisture. Locally heavy downpours can be expected with the flooding threat still remaining limited thanks to recent dry conditions.

By Monday, ridging will be completely flattened by the approaching closed low with embedded shortwaves aloft. Recent southerly flow will become more westerly and will have already advected decent moisture across the entire area, supporting scattered to widespread coverage of convection. By this timeframe, the threat for localized flooding will be more elevated based on the assumption of decent coverage on Sunday. On Tuesday, a very strong upper ridge will be more noticeable across the Southern Plains with continued troughing over our area. This will continue potential for repeated convection capable of heavy rainfall rates and localized flooding.
Additionally, deterministic and ensemble guidance suggests a more impressive thermodynamic environment than in recent days with MLCAPE potentially exceeding 2,000 J/kg. Overall flow will still be fairly weak, but effective shear of 25 kts could be sufficient to provide better storm organization. There is still a lot of uncertainty, but strong/severe convection is definitely possible on Tuesday.

Wednesday through Friday

By Wednesday, the mid/upper ridge will continue to expand from the southwest, promoting hotter temperatures than in the days prior.
Northwesterly flow aloft and hot/humid conditions will continue chances for convection with coverage likely less than early in the week. By Thursday, 500mb heights will reach near 5,940m, which is above the 90th percentile and suggests temperatures rising well into the 90s across the area. Diurnal convection may be even more lessened in comparison to Wednesday. By Friday, additional shortwaves may provide another uptick in convection.

AVIATION
(12Z TAFS)
Issued at 635 AM EDT Sat Jul 27 2024

Patchy fog this morning will dissipate over the next couple hours with VFR conditions prevailing. Iso to sct rain showers will be possible this afternoon, mainly across southern areas near CHA.
Winds remain light.

PRELIMINARY POINT TEMPS/POPS
Chattanooga Airport, TN 88 73 86 71 / 30 20 70 70 Knoxville McGhee Tyson Airport, TN 90 71 87 71 / 20 10 60 70 Oak Ridge, TN 89 70 85 70 / 10 10 70 70 Tri Cities Airport, TN 88 64 88 69 / 0 0 40 50

MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.