textproduct: Jackson

KEY MESSAGES

- Well-above normal temperatures persist into the weekend, with near-record heat observed this afternoon.

- The heat and humidity could fuel isolated thunderstorms across the area at various times over the next several days.

- Rain chances increase early next week as the persistent upper level ridge starts to weaken and then retreat to the southwest.

UPDATE

Issued at 753 PM EDT THU SEP 17 2026

The forecast was updated to curb or remove some PoPs through 02Z this evening. Shower and storm activity has ceased across the area. Minor adjustments were made to the weather and sky grids to reflect the PoP revisions. Latest observational data was also incorporated into the T/Td grids. The forecast remains on track for fog to develop, mainly in valley locations late this evening and overnight before mixing out early Friday. Morning showers will work into the area from the north ahead of a decaying cold front before additional afternoon showers and thunderstorms develop.

LONG TERM

(Saturday through Thursday) Issued at 420 PM EDT Thu Sep 17 2026

The ridging feature that dominated Eastern Kentucky's sensible weather during the short term forecast period is expected to erode as the long term period progresses. A series of shortwave impulses navigating around the ridge's northeastern periphery and a closed upper level low pushing west across the Floridian Peninsula will work in tandem to suppress the ridge this weekend. It is progged to weaken to a loosely-organized, sub-590 decameter ridge over the Ozarks by Monday, a far cry from its peak intensity as a well-defined 600+ decameter "heat dome." As this weakening process occurs, the forecast area will be positioned in somewhat of a split flow regime. The stronger westerlies associated with the jet stream will remain displaced well to the north of the Ohio River through early next week, and as the ridge loses its definition, the winds aloft will weaken and become more quasi- zonal. So, this weekend's sensible weather forecast will largely be governed by smaller scale features and processes.

Some of those mesoscale forecast ingredients are hard to predict at the current temporal range. Machine learning and AI-enhanced probabilistic models are beginning to resolve a corridor of low-end severe storm potential along the NE periphery of the decaying ridge. This will need to be investigated further as convection-allowing, higher-resolution models enter the forecast guidance suite. The weak nature of the flow aloft will limit the magnitude of the shear available for any storms developing within our CWA this weekend, but if a self-sustaining MCS develops somewhere upstream, we will need to monitor its progress. This would cause the forecast to deviate from current expectations, which are more scattered, pulse-type convection during peak diurnal heating hours. Any MCS could also throw a wrench in the temperature forecast, which currently calls for highs in the upper 80s/lower 90s on both Saturday and Sunday. A few isolated hydro impacts cannot be entirely ruled out where multiple rounds of activity occur this weekend, and WPC has accordingly outlined Marginal Excessive Rainfall Outlooks that clip the northern Licking and northeastern Big Sandy River Basins.

There is still a notable increase in model spread within the NBM ensemble across multiple sensible weather forecast parameters for Monday and beyond. This is likely due to differing model solutions surrounding a deeper trough ejecting out of the Plains. Significant variations in this feature's modeled amplitude, orientation, phasing, and forward progression speed continue to preclude the discussion of specific precipitation forecast details, but models generally agree that a deeper, vertically-stacked trough will move through the Midwest and the Greater Ohio River Valley by midweek. It would take a trough like this to finally drag a meaningful cold front through the CWA. So, despite the model spread, there is a noticeable downward trend in the mean NBM forecast temperatures. Highs could dip down into the low/mid 80s by Tuesday, and then the 70s on Wednesday and Thursday. Northern and Northeastern portions of the forecast area are the most likely to reap the benefits of this cool- down, and the cooler air will also reach them first. Thus, the gradual demise of the ridge could give our area a taste of more fall- esque temperatures by the middle of the next work week. Fingers crossed, as this would be welcome relief from the record high temperature observed at our office while this discussion was being typed.

AVIATION

(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 753 PM EDT THU SEP 17 2026

Earlier shower and storm activity has ceased. VFR conditions are expected to start the TAF period. Valley fog is expected to develop anytime after 02Z late this evening, favored in typical river valley or sheltered valley locations. Model soundings suggest boundary layer winds could remain elevated late this evening and overnight, which may favor a low stratus deck over fog. Any locations that received rainfall earlier this afternoon and evening may experience locally dense pockets of fog. A fog reduction into MVFR was added for KLOZ, KSME, and KSJS in the event near-surface winds remain somewhat dampened.

Showers are possible as early as 12Z across northeastern TAF sites such as KSYM, KIOB, and KSJS ahead of a weakening cold front pushing south out of the Ohio Valley. Thunderstorm chances pick up around 18Z at all TAF sites except KLOZ and KSME, where chances begin more toward 20-21Z before tapering off shortly after the TAF period. Showers and storms could lead to MVFR or lower reductions. Winds will remain light and variable through much of the TAF period before increasing slightly Friday afternoon, while remaining below 10 kts.

JKL WATCHES/WARNINGS/ADVISORIES

None.