177 FXUS63 KJKL 261150 AFDJKLAREA FORECAST DISCUSSION National Weather Service Jackson KY 750 AM EDT Fri Sep 26 2025
.KEY MESSAGES...
- Areas of dense fog will create hazardous travel conditions across parts of eastern Kentucky this morning. Please allow extra travel time and use low-beam headlights.
- A few light showers will be possible today and Saturday, mainly for areas near the Virginia border. Expect drier weather and more sunshine to return on Sunday.
- We are monitoring a tropical system that could influence our weather next week. The forecast is extremely uncertain, and it is too early to determine potential impacts.
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.UPDATE... Issued at 750 AM EDT FRI SEP 26 2025
Fog and low clouds prevail across most of the forecast area at update. Everything seems to be on track, so anticipate fog and low clouds gradually lifting through the morning. The Dense Fog Advisory for northern counties runs out at 10 AM EDT.
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.SHORT TERM...(Today through Saturday) Issued at 438 AM EDT FRI SEP 26 2025
At 8z, a mixture of high and low clouds with fog (locally dense) was present across eastern Kentucky, along with a few small, light rain showers over the far southeast. Temperatures range from the low to mid-60s. The latest surface analysis shows a weak cold frontal boundary now to our east, stretching from New England southwestward over the southern Appalachians and beyond to the Central Gulf Coast. The 850 hPa cold front appears to lag the surface boundary and is located just ahead of a mid-level vorticity lobe and a 500 hPa trough axis extending from the St. Lawrence Valley southwestward into eastern Texas. It appears the southern portion of the trough may already be closing off over western Kentucky and Tennessee as the more poleward portion shears off to the east.
Through the remainder of today, that weak upper low will cut off completely from the main flow aloft and drift southward into the Shoals of Alabama. Tonight and Saturday, that low will drift eastward to near or over Atlanta, GA, before drifting back north across the Southern Appalachians by the end of the day. In the meantime, the aforementioned vorticity lobe will be very slow to cross the area today, initiating weak convection (PoPs 5-35%, lowest northwest to highest southeast). Precipitation chances will become increasingly confined to the Virginia border area with time. Precipitation chances will exit to the east this evening. However, additional energy rotating around that new cutoff low will lift into far eastern Kentucky tonight, potentially initiating weak convection, primarily near and east of US-23. Additional weak convection is possible on Saturday, primarily over the eastern half of the forecast area, associated with the energy ejecting out of the weak low. Meager instability, generally less than 750 J/kg of MLCAPE, will limit overall convective vigor both days; any thunder, should it occur, will be a novelty.
In sensible terms, fog (locally dense) and low stratus this morning will lift, giving way to partly sunny skies. Any isolated to widely scattered light showers will shift southeastward with time, becoming confined mostly to areas near the Virginia-Kentucky border. A rumble of thunder cannot be entirely ruled out with the strongest activity this afternoon. It will be mild with high temperatures in the mid to upper 70s. For tonight, clouds will remain persistent over the eastern half of the forecast area, where isolated to widely scattered showers are expected to redevelop late. Better clearing is expected further west and where that persists, fog formation is especially favored in the valleys. It will be cooler, with lows ranging from the mid-50s in the western valleys to the low 60s over far eastern Kentucky. Looking ahead to Saturday, cloud cover will be thicker and more persistent across eastern portions of the area. These clouds will coincide with the highest probability for rain (likely chances in those counties adjacent to the Virginia-Kentucky border) but a shower cannot be ruled out as far west as the Pottsville Escarpment. A stray thunderstorm also cannot be ruled out. Saturday will be similarly mild again with high temperatures in the mid 70s to around 80.
.LONG TERM...(Saturday night through Thursday) Issued at 606 AM EDT FRI SEP 26 2025
The long-term period opens Saturday evening with a weak inverted surface trough over far eastern Kentucky, while a weak ~578 dam low is situated nearby over the Southern Appalachians. That upper low moves further east by Sunday, with northerly flow helping to dry out the air mass. This will result in more sunshine and mostly dry conditions. Only the far eastern counties have a slight chance of showers and thunderstorms. The evolution of the low will play an important role in how a tropical system (currently a disturbance near/over Haiti) affects the southern and central Appalachians next week. Confidence in the tropical system`s track and any potential impacts on eastern Kentucky remains extremely low. Model spread and run-to-run inconsistency is unusually large, no changes were made to the NBM from Monday onward. Nighttime ridge-to-valley temperature splits were added for Saturday and Sunday nights, along with the typical nocturnal valley fog. Temperatures are expected to start the period near seasonal norms.
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.AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 748 AM EDT FRI SEP 26 2025
Conditions varied widely from VLIFR to VFR at TAF issuance. As the morning passes, the lingering fog and low stratus will lift and allow VFR conditions to return to all terminals for this afternoon and evening under an extensive cumulus field. There is a small chance of a shower or storm over far southeastern Kentucky, especially this afternoon, but TAF site impacts are not expected at this time. Fog formation is likely again in many of the river valleys but impacts on the main terminals is uncertain at this time. Light northerly winds will be the rule during the period.
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.JKL WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 10 AM EDT this morning for KYZ044- 050>052-059-060.
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UPDATE...GEERTSON SHORT TERM...GEERTSON LONG TERM...GEERTSON AVIATION...GEERTSON
NWS JKL Office Area Forecast Discussion