Expires:No;;329310 FXUS63 KJKL 170553 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 153 AM EDT Mon Aug 17 2026 .KEY MESSAGES... - The potential for showers and thunderstorms will persist through Monday. - Some of the storms could arrive as organized clusters with a possibility for strong to damaging wind gusts. - Excessive rainfall may occur where storms are most persistent, or train, leading to flash flooding. && .UPDATE... Issued at 821 PM EDT SUN AUG 16 2026 Convection, some of it severe has blown up over the northern part of the area this evening, and the POP has been raised to accommodate it. Persistent or training cells have largely been outside our area so far, but problems could arise shortly and it will be monitored. && .SHORT TERM...(This evening through Monday night) Issued at 425 PM EDT SUN AUG 16 2026 Late this afternoon, an upper level ridge was centered in northeastern portions of TX and extending into parts of the Southeast and TN Valley. A shortwave trough is passing through the eastern Great Lakes to the Lower to Middle OH Valley while another shortwave trough/MCV is upstream over the IA to MO vicinity. At 500 mb, a trough extended from Hudson Bay to Ontario to northern Great Lakes and was approaching the Ontario and Quebec area. At the surface, an area of low pressure was moving through James Bay to Ontario and Quebec border region with a warm front lifting through NC and parts of the mid Atlantic while a cold front trails into the mid MS Valley to KS and OK border region. For the most part, cumulus thus far has struggled to persist and develop vertically. An outflow boundary/wind shift, has moves into areas near the I-64 corridor and is nearly stationary. A thunderstorm did develop in its vicinity in Rowan County and moved across Elliott County and then into Lawrence County. Recent mesoanalysis has MLCAPE on the order of 2000 J/kg near the WV and KY border and 2000 to 2500 J/kg near Lake Cumberland with 1500 to 2000 J/kg over the remainder of the area or central part of the CWA. Mid level lapse rates are generally 5.5C to around 6C while low level lapse rates are more substantial between 7 and 8C/km. Effective shear is 20 to 25KT in the norht and east, with lesser values further south. Over the next few hours, MLCAPE per SPC Mesoanalysis RAP based forecasts peak in the 2000 to 2500 J/kg through around sunset with mid level lapse rates remaining around 6C/km with low level lapse rates steep for a couple more hours before diminishing to under 7C/km toward sunset. Effective shear may increase a bit as the shortwave passes through parts of the OH Valley to the Central Appalachians into the 25 to 30KT range. This may support some additional isolated to scattered convection through portions of the evening and some stray convection has developed in parts of central KY. Convection in IL and nearing IN weakens in some of the CAMS and what is left of that may pass north of eastern KY later this evening though confidence in the evolution of that. Then after midnight, the upstream shortwave/MCV should approach eastern KY from the west in the form of a potential MCS. PW though at a bit of a min at present, especially south where values are in the 1.6 to 1.7 inch range. These values should trend up during the evening and into the overnight per the 12Z HREF into the 1.8 south to 2.0 to 2.1 inch vicinity in the north of near 90th percentile south and 93 to 97th percentile in the north. Any more organized convection could produce strong wind gusts and any training could result in instances of flash flooding. SWODY1 and Day 1 EROs are in alignment with this reasoning. On Monday, the overnight shortwave/MCV and potential MCS should pass east of eastern KY early on Monday as the cold front reaches the Commonwealth. At least moderate instability with MLCAPE in the 2000 to 3000 J/kg range may develop ahead of the front on Monday with effective shear on the order of 25 to 30KT. This may support some organized convection with the south possibly more favored with expected higher instability. A Marginal to Slight Risk SWODY2 has been issued for tomorrow for those concerns with wind the primary hazard along with torrential downpours as 1.8 to 2.1 inch PW should be prevalent. Any training again would pose a risk for high water or flash flooding. The 500 mb trough axis moves further east by Monday evening and this should eventually push the cold front to the south and southeast of the JKL CWA by around midnight on Monday night leading to an eventual diminishment of convection. .LONG TERM...(Tuesday through Sunday) Issued at 353 PM EDT SUN AUG 16 2026 At the onset of the long term period, a strong closed upper level low will sit over Manitoba, with general troughing over the northern CONUS, especially in the vicinity of the Great Lakes. Meanwhile, a relatively flattened ridge will linger over the southern US, with eastern Kentucky finding itself in a region of zonal to slightly northwesterly flow aloft, depending on the orientation of ridging. At the surface, the previous frontal system will be south of the forecast area, having fully moved through, and surface high pressure will be building near the Middle Mississippi Valley. Behind the surface high, a secondary cold front associated with the relatively vertically stacked Canadian low will extend southward into the Upper Midwest. As these features travel eastward, building high pressure over the forecast area will keep eastern Kentucky largely dry on Tuesday. Temperatures will be fairly seasonable as well, with highs ranging from the mid to upper 80s across the forecast area. Clear skies overnight may allow a very modest ridge/valley temperature split to develop, with the limiting factor being lingering moisture. MOS guidance is rather aggressive with these splits, but given expected moisture, valley minTs have been nudged down only modestly into the low 60s for now. Of note, fog formation on Wednesday morning appears likely for much of the forecast area, particularly in typical mainstem river valleys. Dry weather will persist through much of Wednesday as surface high pressure continues to translate through the area. Meanwhile, the upper level trough will continue to dig towards the Commonwealth, with the aforementioned cold front pushing southeast. By Wednesday evening, the front will approach eastern Kentucky and rain chances will return to the area. Of note, some models depict an additional shortwave traversing the base of the trough (roughly centered over the Ohio Valley) around the time frontally forced convection approaches, or perhaps slightly before. This enhanced mid level flow may elevate shear somewhat, and depending on frontal timing, instability may also be adequate for stronger storms, although model spread remains quite high at this time. Any risk for severe weather (or lack thereof) remains dependent on how these ingredients line up, with overall risk looking quite low at this time. Meanwhile, a moist air mass will be in place ahead of the front, with LREF mean PW values generally in the range of 1.6-1.7 in (roughly 80th percentile or higher compared to climatology). This, in addition to potentially enhanced convective coverage if shortwave energy interacts with the front, could allow for at least isolated instances of flash flooding. Again, model variability remains very high at this stage, but WPC has already outlined the forecast area in a Day 4 Marginal (Level 1/4) Risk for Excessive Rainfall on Wednesday, and an additional Day 5 Marginal Risk on Thursday as the system sags south. Guidance does suggest the front will slow as it passes through the southern portion of our area and into Tennessee. Exactly how quickly this boundary progresses is still a source of uncertainty, but rain chances have been maintained through Thursday to account for this slowing motion. Any hydrological concerns will also be dependent on the speed of this frontal passage in addition to the extent of convective coverage. Following the frontal passage, troughing will continue to amplify, eventually digging all the way into the Southeast as ridging retreats towards the Four Corners region. This will usher in cooler weather, with high temperatures as low as the upper 70s for some locations on Friday (and perhaps lower if convection can take hold). Additional impulses will keep at least scattered showers and storms in the forecast each day, with rain chances generally peaking in the afternoon/evening. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 153 AM EDT MON AUG 17 2026 Aside from highly isolated weak convection, VFR conditions were noted over the terminals at the 06Z TAF issuance. Given recent rainfall, radiation fog formation is possible in the most sheltered valley locations early this morning, but modest low- level winds just off of the surface are likely to keep any more widespread fog formation in check. A cold front will approach the area during the daylight hours Monday with two or more rounds of convection possible. The first round of storms is over the Lower Ohio Valley and could reach more northern terminals by daybreak. Guidance continues to struggle with the evolution of this system, so forecast confidence in impacts at the terminals is somewhat low. Another round of convection is then expected during the afternoon and evening hours just ahead of/along the cold front. Winds will generally be light and variable early this morning, becoming southwest after daybreak before shifting northwest late in the day behind the cold front. Winds will generally remain around 10 kts or less, but could be locally strong and erratic near thunderstorms. && .JKL WATCHES/WARNINGS/ADVISORIES... Flood Watch until 6 AM EDT early this morning for KYZ058>060-068- 069-106>120. && $$ UPDATE...HAL SHORT TERM...JP LONG TERM...FAGAN AVIATION...GEERTSON