FXUS63 KJKL 211120 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 720 AM EDT Sun Jun 21 2026 .KEY MESSAGES... - Mainly dry weather is expected through this afternoon. - Showers and thunderstorms will make a return this evening or overnight tonight and Monday, possibly bringing heavy rainfall along with strong wind gusts. && .UPDATE... Issued at 627 AM EDT SUN JUN 21 2026 There are no changes to the forecast. Hourly T/Td grids using the latest hourly observation as the initialization for the forecast. && .SHORT TERM...(Today through Monday) Issued at 250 AM EDT SUN JUN 21 2026 An unusually active jet stream persists across the Ohio Valley through the short-term period. A weak disturbance will exit the area to the east this morning within west-northwesterly flow aloft, with a weak front near the I-64 corridor having served as a focus for isolated shower and thunderstorm development last evening into the overnight. Progressive shortwave ridging moves across the area today ahead of the next disturbance which will push increasing moisture northeast across much of eastern KY later today into the overnight tonight. PoPs increase from the west this evening into the overnight, but there is considerable uncertainty on location, magnitude, and timing of any MCS activity that is likely to be traversing the Ohio River Valley, with some models depicting little if any precipitation and other models depicting a very active overnight period with multiple rounds of showers and thunderstorms. Have thus opted to stick pretty close to the NBM with regards to PoPs and QPF. If convection were to enter the area from the west tonight, there is a Marginal Risk for severe storms, with damaging winds the primary threat. Storms would likely weaken as they outrun better low-level moisture and instability as they move east into far eastern Kentucky, but would still pose a threat for excessive rainfall, with a Slight Risk remaining for our far northern counties late tonight and a Marginal Risk for adjacent areas to the south and east. Additional disturbances move east from the center of the country toward and across the OH/TN Valleys Monday into Monday evening, with a surface low traversing eastward just north of the Ohio River and an accompanying cold front extending southwest through Kentucky into Tennessee. Strong moisture advection in the low levels of the atmosphere will allow for an increase in instability into eastern Kentucky, setting the stage for numerous to widespread thunderstorm activity through the daytime period, peaking in the afternoon through early evening before diminishing with the passage of the cold front. A few of these storms could be on the strong side, with damaging winds again the primary threat. A Flash Flood Watch was considered with this forecast package for all or part of the tonight through Monday period, but ultimately not issued (at least for now) owing to the considerable uncertainty with regards to convective activity tonight and Monday. This may need to be revisited later today should models allow for better clarity on the forecast details during this time. .LONG TERM...(Monday night through Saturday) Issued at 1246 AM EDT Sun Jun 21 2026 When the long term forecast period opens on Monday evening, there will likely be ongoing showers and thunderstorms across Eastern Kentucky. As discussed above, this lingering convection may initially pose a risk for gusty winds and heavy rainfall. However, the intensity of this activity is poised to decrease after sunset. The loss of diurnal heating and rain-cooled air will combine to reduce instability to below favorable values. This, in turn, should allow rainfall rates to wind down overnight, with only light showers remaining in SE KYby Tuesday morning. The parent cold front looks to finally clear the entire CWA by midday Tuesday. A shortwave trough axis propagates into the southern Appalachians in this time frame and places Eastern Kentucky in a vertically stacked northwesterly flow regime. Orographic lift could yield a few additional sprinkles in the higher southeastern terrain on Tuesday afternoon, but midlevel height rises and the advection of a cooler and drier airmass into the area should prevent any additional impacts. Expect seasonably cool afternoon highs in the upper 70s behind the boundary under clearing skies, which will then favor overnight ridge-valley temperature splits into Wednesday morning. Given the recently wet grounds, expect nocturnal radiation fog to form in at least the conventional river valleys. That fog should burn off as the sun rises on Wednesday, which will be a pleasant summer day under the influence of a postfrontal surface high pressure system. The flow aloft returns to a progressive quasi-zonal flow regime by midweek, with passing shortwave disturbances triggering occasional precipitation chances. As the aforementioned surface high shifts east into Thursday, southwesterly wind components reintroduce warm air advection and moisture return to the column. Highs accordingly return to the mid/upper 80s through the remainder of the period, but increasing model spread regarding the timing and amplitude of those late period impulses makes it difficult to pinpoint precipitation forecast details. PoPs are accordingly relegated to below the 50% mark in the blended forecast guidance used to populate the long term grids, and it may be more reasonable to describe this shower/storm activity with isolated/scattered coverage wording. In other words, expect typical summertime weather conditions towards the end of the long term forecast period. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 720 AM EDT SUN JUN 21 2026 Outside of any valley fog lingering through ~13z this morning, VFR conditions will prevail into tonight. Uncertainty arises after 02z Monday as to the magnitude, location, and timing of upstream convection which may move toward or through the area before the end of the TAF period. KIOB and KSYM would be most likely to first see such activity, perhaps as early as 02z, with the remainder of TAF sites having the possibility of convection before the end of the TAF period. The uncertainty in the forecast warrants coverage with primarily PROB30 groups. Winds will be light and variable or south to southwest at 7 kts or less through this afternoon, but will begin to increase this evening into the overnight as a cold front approaches from the west. A low-level jet will also develop, and may produce localized LLWS, especially after 06z tonight. Light winds overnight will trend southerly to southwesterly at 7 kts or less during the afternoon hours, and will likely continue into the late evening at more exposed locations such as KSME and KIOB. && .JKL WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...CMC SHORT TERM...CMC LONG TERM...MARCUS AVIATION...CMC