textproduct: Jackson

KEY MESSAGES

- A significant cold front could produce multiple rounds of thunderstorms on Tuesday and Tuesday night. Those storms will be capable of severe weather and excessive rainfall.

- Mainly dry weather is expected from Wednesday night to Friday with temperatures averaging about 5 degrees below normal.

LONG TERM

(Tuesday night through Sunday) Issued at 445 AM EDT MON JUL 20 2026

At the start of the long term period, the area sits ahead of a potent cold front. This front is initially expected to extend across the eastern Great Lakes to Lower OH Valley from a sfc low in Canad to the south and southeast of James Bay. Also at that point, a shortwave trough is expected to be rotating through the Great Lakes to OH and TN Valleys.

A model sounding from the 00Z suite of data shows conditions at 01Z Wednesday (9 PM Tuesday) as follows: MLCAPE around 2000 J/kg, Effective Bulk shear of 35-40 kts, 0-1 km SRH around 170 m2/s2 and 0-3 km SRH near 290 m2/s2, and DCAPE near 1300-1400 J/kg. Different models also suggest that PWAT could remain between 1.75 and 2.00 inches ahead of the cold frontal passage during the late evening and into the night. The above parameters highlight an environment favorable for organized cells to sustain updrafts given models sounding hodographs showing a critical angle of 92 degrees (near textbook orthogonal flow). With DCAPE of 1300 J/kg, wet microbursts are also favored, where severe downburst winds of 60-70 mph gusts or more could be possible. While low-level kinematics could still support discrete or semi-discrete storms near sunset, the high DCAPE and potential strong cold pool development and forcing from the front suggest storms will likely consolidate quite rapidly into a bowing QLCS/MCS by around or shortly after sunset. In summary, the greatest weather threat appears to be strong to severe damaging wind gusts, though isolated tornadoes and large hail around quarter-size cannot be ruled out. As such, the SPC has put the area in a Day 2 Enhances Risk (Level 3 of 5) for Severe Weather, covering an area near and north of the Mountain Parkway with a Slight Risk (Level 2 of 5) for Severe Weather elsewhere.

To add to a busy Tuesday evening mean PWATS of 1.75 to 2.00 inches across the area fall within the 97th to 99th percentile against climatology. Integrated water vapor transport will also approach the 99th percentile of climatology during this timeframe. With days of repetitive rainfall having already primed soils, any storms late in the evening into the overnight could produce additional periods of heavy or torrential rainfall which could lead to isolated to scattered instances of flash flooding. As such, the WPC has all of the forecast area in a Slight Risk (Level 2 of 4) for Excessive Rainfall meaning isolated to scattered instances of flash flooding will remain possible into the evening.

The cold front is expected to be south of the forecast area by Wednesday morning, though isolated to scattered showers and storms will linger through the morning, with chances tapering by evening, as high pressure builds into the area. Quiet conditions are expected across Eastern Kentucky from Wednesday night through the better half of Friday. However, models and ensembles depict the next system ejecting out of the Central Plains later Friday and Friday night into the Tennessee Valley and then gradually across portions of the Southern Appalachians/Southeast. This scenario leads to renewed shower and storms chances Friday evening, through Sunday. At present, chances look to remain isolated to scattered in nature (15-35% chance), with the best chances further south nearer to the VA and TN borders.

Temperatures will generally be 5 degrees below normal to start the extended, ranging from the upper 70s to low 80s Wednesday and Thursday following the cold frontal passage Tuesday night. Temperatures then generally warm to the mid to upper 80s for highs this weekend. Overnight lows will range from the upper 60s to around 70 for Tuesday night, settled into the upper 50s to lower 60s Wednesday and Thursday nights, and trend milder into the mid to upper 60s for most locations each night Friday though Sunday.

AVIATION

(For the 06Z TAFS through 06Z Monday night) ISSUED AT 235 AM EDT MON JUL 20 2026

At issuance time, a mixture of low clouds/stratus as well as fog was over the south near a stalled boundary while further north valley fog had formed and there also a few passing low and mid clouds there as well. In some areas the fog and or stratus was resulting in IFR or lower reductions. Further fog and or stratus development during the first 6 hours of the period is the main aviation concern. South of a KJKL to KSJS line, recent trends and guidance support reductions to near or below airport mins for a few hours through 14Z with KSME and KLOZ expected to be affected. KSJS and KJKL should eventually have MVFR to IFR reductions as fog lifts into those areas. At this point, VFR is expected to remain throughout the entire period for KSYM and KIOB. Fog and any low clouds should dissipate between 12Z and 15Z, giving way to prevailing VFR conditions through the remainder of the period. With the boundary lingering over the area isolated to scattered showers and storms may affect locations generally south of a KSME to KLOZ to KJKL to KLOZ line after 16Z. Winds will be light and variable outside of any storms.

JKL WATCHES/WARNINGS/ADVISORIES

None.