862 FXUS63 KJKL 251150 AFDJKLAREA FORECAST DISCUSSION National Weather Service Jackson KY 750 AM EDT Thu Sep 25 2025
.KEY MESSAGES...
- The threat for isolated flooding will continue into this morning, especially where heavy rain persists.
- Widespread rain will taper to scattered showers by late morning. A daily risk for isolated showers will then continue through the weekend, mainly near the Virginia and Tennessee border.
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.UPDATE... Issued at 750 AM EDT THU SEP 25 2025
The band of precipitation has weakened significantly, as expected, and is now over far eastern Kentucky. Behind that exiting band, anticipate isolated to scattered showers through the morning with a few thunderstorms possible, mainly this afternoon. Latest CAMs and obs have been blended into the hourly forecast to capture the latest near-term trends.
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.SHORT TERM...(Today through Friday) Issued at 342 AM EDT THU SEP 25 2025
While most of eastern Kentucky is currently experiencing a lull in rainfall, regional radar mosaic shows a pronounced band of rain with embedded convective elements extending from Southeast Ohio to Middle Tennessee. The band is pivoting slowly counterclockwise around a fulcrum point: a ~1008 mb surface low centered near Cincinnati. The low is tracking along a wavy frontal boundary extending from the Southern New England through the Mid- Atlantic southwestward along the Ohio River and then further southwest into Texas. Aloft, a positively-tilted trough axis extends southwest from a parent low over northern Michigan to over Texas. A 20 to 30 kt southwesterly flow at 850 mb continues to feed a moisture-rich airmass (PWATs of 1.7 to 1.8 inches) into the low`s circulation, ascending into a 300 mb jet over Lake Erie. This deep-layer moisture feed, along with a deep warm-cloud layer, will continue to support efficient rainfall production.
Through the remainder of the morning, the concern for isolated flooding remains, particularly if torrential downpours persist over a given area. The threat is highest near and north of I-64, where the band is pivoting more slowly. The upper-level trough will slowly translate eastward through the day, with its associated support steering the surface low with it. Consequently, the steadier precipitation will taper from west-to-east between 8 AM and noon. With better forcing over the north, southern portions of the precipitation band may tend to weaken or become broken as it transits the area, keeping overall lighter rainfall amounts in the south and heavier rainfall amounts in the north. NBM favors closer to one-third of an inch over the southeast up to 1 inch north of I-64 through 18z, though this reflects the general gradient and not the absolute max and min values (additional amounts exceeding 2 inches cannot be ruled out at isolated northern locales where heavy rainfall is most likely to persist). Once the surface low pulls away, PWATs will decrease to under 1.5 inches as the column dries aloft. There will still be sufficient low-to mid-level moisture, however, for scattered showers and perhaps some weak thunderstorms through the remainder of the day, as upper-level perturbations eject from the trough axis and interact with weak diurnal destabilization. Convective vigor and depth will be limited by the meager CAPE profiles (MLCAPE 400-800 J/kg per the RAP13), though ample shear will be present (EBWD >30 kts). As daytime heating diminishes this evening, convection will wane. Overnight, abundant low clouds and fog will persist within a saturated, moist-adiabatic layer from the surface to 800 mb as the wavy cold front seeps southeast. Meanwhile, the upper-level trough will pull away to the northeast while the southern portion of the trough shears off, with its energy consolidating into a weak closed low near or over Nashville, TN. Cyclonic flow around the low will combine with the lingering shallow moisture to promote substantial cloud cover on Friday but dry air and weak lapse rates in the mid-levels will strongly limit convection depth and vigor.
In terms of sensible weather, expect showers and embedded thunderstorms to develop from west to across eastern Kentucky through sunrise before gradually tapering from the west through the remainder of the morning. Rainfall amounts of one-third to 1 inch should be common, but locally higher amounts leading to high water and flash flooding cannot be ruled out, especially near and north of I-64. Scattered to numerous showers and thunderstorms are then possible through the remainder of the day. It will be mild with highs in the mid 70s. For tonight, expect extensive low clouds and fog, with patchy light rain or drizzle possible, and lows in the low to mid-60s. On Friday, expect a mix of sun and clouds with a low chance of showers and thunderstorms southeast of I-64; the highest chances will be near Middlesboro. It will again be mild with highs in the mid 70s for most locations.
.LONG TERM...(Friday night through Wednesday) Issued at 506 AM EDT THU SEP 25 2025
Though the weekend should tend to be drier overall, the lingering upper-level low will tend to keep ample cloud cover as well as a daily risk of isolated to widely scattered showers over portions of the area, particularly closer to the Virginia and Tennessee border. There is still significant uncertainty early to mid-week with evolution of the upper-level low. The previous discussion still covers the long-term pattern well.
Previous discussion issued at 235 PM EDT WED SEP 24 2025
For Friday, a positive upper trough axis will continue to move slowly into the central and southern Appalachians with the frontal boundary moving well southeast of the area. However, an inverted surface trough will remain just south and east of the area.
Shear axis and associated Q-Vector forcing will keep chances of showers especially areas near the KY/VA and KY/TN state-lines. CAPE looks quite limited so thunder chances quite low.
For much of the extended period from Friday through at least Monday the ensemble cluster analysis along with the latest deterministic models are showing an upper trough axis being cut-off over the Tennessee valley and central/southern Appalachians and weakening. During this period, shear axis will rotate around this upper low producing periods of better Q-Vector forcing and deformation zone forcing. An inverted surface trough is also anticipated.
Ensemble CAPE probabilities do increase for Saturday, Sunday, and Monday with afternoon values of 250-500 possible. This is likely due to more sunshine in the afternoon hours. End result will be greater coverage of diurnal showers and possibly thunderstorms. Threat for strong to severe storms is quite limited. Greatest coverage will likely remain near the KY/VA and KY/TN state-line.
For Tuesday and Wednesday, confidence is low on how this closed off and weakening upper low will effect the area. Can not rule out a slight chance of mainly diurnal convection.
Sky cover becomes less for late this weekend into early next week which will allow for better radiational cooling conditions so will modify the mins for the valley/ridge temperature differences. Nighttime and morning fog will become more likely as well some dense.
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.AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 750 AM EDT THU SEP 25 2025
At TAF issuance, conditions varied widely from LIFR to VFR across the area. Steadier precipitation over far eastern Kentucky will exit east by 13-14Z, leaving isolated/scattered showers. Generally MVFR to low VFR ceilings are expected today and a modest increase in shower and thunderstorm activity is forecast this afternoon before tapering this evening. Widespread low clouds and fog should develop tonight. Southerly winds will gradually veer west to northwest through the day, generally at less than 10 kts.
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.JKL WATCHES/WARNINGS/ADVISORIES... None.
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UPDATE...GEERTSON SHORT TERM...GEERTSON LONG TERM...GEERTSON AVIATION...GEERTSON
NWS JKL Office Area Forecast Discussion