textproduct: Jackson

KEY MESSAGES

- Showers and isolated thunderstorms may redevelop this afternoon into the evening before tapering off from northwest to southeast through Thursday morning.

- Much cooler air settles in Thursday and Friday. Lows on Thursday night will dip into the mid to upper 30s in valleys, bringing the potential for fog and localized patchy frost.

- A warming trend begins this weekend with highs returning to the mid to upper 70s by Sunday.

- Periodic chances for showers and thunderstorms return to the area for the upcoming weekend and into early next week.

LONG TERM

(Thursday night through Tuesday) Issued at 224 AM EDT WED MAY 6 2026

The long term forecast period opens on the backside of the shortwave troughing responsible for the active weather described above. As that feature ejects east, subtle midlevel height rises and a building surface high pressure system suggest that a clearing trend will emerge on Thursday evening. A shift to more northwesterly winds aloft will advect a drier, continental airmass into the region, but surface winds will be light and variable given the weak pressure gradient. Collectively, this suggests that Thursday night's sensible weather will be driven by localized topographic effects.

Assuming that clearing trend comes to fruition, ridge-valley temperature splits are expected to emerge after sunset on Thursday evening. Sheltered and shaded hollows will see the most efficient radiational cooling and thus the coolest overnights. Temperatures in the mid 30s there could pose a risk for patchy frost development by Friday morning. In the main stem river valleys, the presence of additional moisture should insulate MinTs in the upper 30s/lower 40s. Given that similar post-frontal set-ups have recently produced patchy valley fog, fog was added to the grids along the Cumberland, Kentucky, Red, Licking, and Levisa/Tug Fork Rivers with tonight's forecast package. Greater fog coverage may be needed in future forecast updates, especially if grounds are wet by any additional rainfall on Thursday. The risk for frost/fog lowers as elevation increases, and ridgetop locales are the most likely to remain in the mid 40s on Thursday night.

Thursday night's surface high is forecast to quickly pass through the forecast area on Friday. Its proximity allows Friday's daytime hours to stay dry and mild, but southwesterly surface flow emerges on its backside by Friday afternoon. These winds will advect a relatively warmer airmass into the region for the end of the week. Highs rebound into the upper 60s/lower 70s on Friday afternoon, and lows stay near the 50 degree mark on Friday night amidst increasing cloud cover. A midlevel disturbance arriving around midnight on Saturday morning will work with the warmer air to produce some AM showers and storms, but misalignment with the diurnal instability cycle and the shallow nature of the antecedent moisture return will limit the intensity ceiling of this convection. LREF mean PWATS peak at a piddly 0.80 inches in the Bluegrass on Saturday morning, then decrease the further one goes into the higher terrain of SE KY on Saturday afternoon. The better forcing with this system is also contained to northern portions of the forecast area, as the parent disturbance aloft looks to eject NE and abandon the surface boundary on Saturday afternoon. Any early-day activity along the I-64 corridor should accordingly weaken as it moves deeper into the CWA after sunrise, and Saturday's PoPs accordingly follow a North-South gradient. Rain chances above 40% are limited to locations north of the Mountain Parkway, and the Cumberland River Basin may stay dry.

The above boundary becomes diffuse across the forecast area on Saturday night, resulting in seasonably mild and calm conditions. Another night of ridge-valley splits is possible, but with less concern for frost and fog. Given the lack of post-frontal cold air advection, temperatures are generally forecast to remain above the 50 degree mark on Saturday night. This gives Sunday's temperatures a head start and sets the stage for more widespread showers and storms on Sunday afternoon/evening. Sunday's setup features more vertically stacked southwesterly flow and thus a more effective warm air advection/moisture return regime. Breezy southwesterly flow will yield highs in the upper half of the 70s and dewpoints in the upper 50s/lower 60s on Sunday afternoon. LREF mean PWATs climb to around 1.15 inches in this same time frame, which suggests that Sunday's showers and storms will be more meaningful than Saturday's. The risk for severe weather does not currently appear particularly high, but the currently-available ML/AI/analog guidance collectively resolves marginal-esque probabilities in Southern Kentucky with this setup. It is possible that those pieces of guidance are picking up on the potential for a more favorable strong storm environment to emerge on the warm side of the previous day's stalled out boundary. The LREF joint probabilities for marginally favorable convective parameter spacing (>500 J/kg CAPE, <-25 J/kg CIN, and > 30 knots effective bulk shear) are in the 30-40% range south of the Mountain Parkway. While the higher probabilities are confined to the south in the Tennessee Valley, the progression of Saturday's boundary and the related convective model trends on Sunday are worth watching.

Broader longwave troughing digs into the Greater Ohio River Valley on Monday, setting up a postfrontal northwesterly flow regime from the surface to the midlevels. Expect a cooler and drier airmass to move into the commonwealth for the start of the next work week as a result. After skies clear from west to east on Monday, drier weather persists on the backside of that trough through Tuesday. The progressive nature of the overarching synoptic pattern means that the aforementioned trough is likely to lift into New England by mid week though. Quasi-zonal flow should emerge over the forecast area in its wake, but forecast models diverge from there. There is significant disagreement surrounding the timing and evolution of a potential system at the very end of the period, but there is a stronger signal for a warming trend out ahead of it. The CPC Days 8- 14 Temperature Outlook, which begins at the end of the period on Wednesday, May 13th, suggests that temperatures are trending above- normal for mid-May in Eastern Kentucky. This is good news for our frost-sensitive interests, but they are encouraged to pay close attention to Thursday night's frost forecast in the mean time.

AVIATION

(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 201 PM EDT WED MAY 6 2026

At TAF issuance, shower activity has mostly diminished across the area. A weak wave riding the boundary may push renewed light shower activity back to the north for several hours late this afternoon and evening but should still remain southeast of I-64. MVFR to IFR ceilings and visibilities are prevalent and are expected to remain through the majority of the TAF period. Conditions should improve beyond 14Z at most locations into MVFR or VFR conditions. Winds are generally under 10 knots becoming light and variable tonight. There may be periods of patchy fog this evening generally after 06Z.

JKL WATCHES/WARNINGS/ADVISORIES

None.