400 FXUS63 KJKL 211909 AFDJKLAREA FORECAST DISCUSSION National Weather Service Jackson KY 309 PM EDT Sun Sep 21 2025
.KEY MESSAGES...
- A few thunderstorms could become strong to severe this afternoon and evening, especially for the western half of eastern Kentucky. The main threat will be isolated damaging wind gusts. Additional strong to severe thunderstorms are possible on Monday.
- Widespread, beneficial rainfall is expected this week, which will help to improve ongoing drought conditions.
- An additional threat for strong thunderstorms may develop on Thursday, but there is still high uncertainty in the forecast for late this week.
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.SHORT TERM...(This evening through Monday night) Issued at 309 PM EDT SUN SEP 21 2025
A split-flow pattern continues with the southern stream becoming more active across the center of the country. A quasi-stationary longwave trough remains trapped to the south of a blocking high over central Canada. Disturbances continue to move through the west- southwesterly flow across the Ohio Valley, resulting in an unsettled weather pattern for the short-term.
A Marginal Risk for severe storms remains in effect given CAPE values approaching 2000 J/kg along with a band of mid-latitude westerlies producing effective shear values in the 20 to 25 kts range. This is supportive of pulsy convection capable of producing gusty winds and half-inch hail, with an isolated instance of damaging winds possible if a storm were to become organized.
Warm advection remains into tonight, but models indicate increasing stability despite stronger shear moving over the area. Would thus expect shower and thunderstorm chances to continue, but not as strong or widespread as this afternoon into early this evening.
A better threat for a few stronger storms arrives Monday as a stronger upper tropospheric disturbance and the core of stronger mid- level winds move across the area coincident with peak diurnal heating in the mid- to late afternoon period. The SPC has thus continued a Marginal Risk for severe storms for all of eastern Kentucky for Monday. The upper tropospheric disturbance does not exit the area until late Monday night, keeping showers and thunderstorm chances in the forecast.
.LONG TERM...(Tuesday through Sunday) Issued at 309 PM EDT SUN SEP 21 2025
A stronger upper disturbance rounds the base of the longwave trough Monday into Tuesday which becomes stretched from southeastern Canada southwest to the center of the country, with an upper low becoming established over the center of the country. Additionally, a seasonally strong westerly jet stream becomes established Tuesday from the Four Corners region east to the Mid-Mississippi Valley. This jet then becomes increasingly more southerly with time through Friday morning as a high-amplitude trough becomes established from the Great Lakes to the northern Gulf of America. By next Saturday, the GFS and ECMWF begin to diverge as to whether this trough closes off into an upper low over eastern Kentucky, or whether the associated trough becomes embedded within a highly amplified upper trough over the eastern U.S.
A very active weather pattern is expected Tuesday through Friday, with the potential for excessive rainfall each day (Marginal Risks Monday and Tuesday, Slight Risks Wednesday and Thursday), as well as one or more severe weather threats later Wednesday through Thursday, with the highest uncertainty involving how much instability is available within a strong warm advection pattern with strong mid- level winds. Interests in the eastern Kentucky region should remain weather aware and keep monitoring forecasts as this pattern evolves.
High temperatures will continue to trend downward each day as unsettled weather continues through the period, with low temperatures remaining elevated through at least Thursday night. There will be the potential for cooler low temperatures Friday night and beyond with the potential for cold advection depending on the evolution of the mid-level pattern.
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.AVIATION...(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 750 AM EDT SUN SEP 21 2025
Valley fog has developed early this morning but is expected to dissipate by 14Z without affecting any TAF sites. Showers and storms should develop between 16Z today and 02Z Monday. Isolated to scattered storms could affect some or all of the TAF sites during that time with reductions to MVFR or lower anticipated. Winds outside of showers and storms will be light and variable, becoming light out of the south to southwest at 5 to 10 KT after about 15Z.
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.JKL WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...CMC LONG TERM...CMC AVIATION...GREIF
NWS JKL Office Area Forecast Discussion