482 FXUS63 KJKL 182013 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 413 PM EDT Wed Jun 18 2025 .KEY MESSAGES... - Showers and thunderstorms are expected at times through Thursday, with the potential for high water or flash flooding. - Some storms this evening into tonight and on Thursday could produce strong to damaging wind gusts. - Seasonably warm high temperatures are forecast through most of the week, with heat then building during the weekend and especially the first half of next week. && .SHORT TERM...(This evening through Thursday night) Issued at 355 PM EDT WED JUN 18 2025 Late this afternoon, an upper level ridge was centered east of the southeast US Coast while an upper trough extended from the Northern Great Lakes to mid MS Valley to the Arklatex vicinity. One or more weaker shortwaves were moving across the OH Valley and Great Lakes regions in advance of the trough axis. Meanwhile upper level ridging was centered off the Baja of Mexico coast and extended into the Southwest Conus to parts of the Southern Plains as well as north into parts of the Northern Rockies. Further northwest, an upper level low was nearing the coast of BC with an associated south that was nearing the Pacific Northwest. At the surface, a frontal zone extended from low pressure in Quebec to a sfc low in IL and then south and southwest to the Southern Plains. Locally over eastern KY heating of a moist airmass into the 80s dewpoints in the upper 60s near the VA border and low to mid 70s elsewhere has resulted in MLCAPE analyzed at 1500 to 2500 J/kg with MUCAPE near 3000 J/kg. Shear is rather low end generally 20 to 25KT in the east with a min in shear near the I-75 corridor while shear increases further west nearer to the approaching boundary and trough. Low level lapse rates are currently analyzed from near 6.5C/km or 7.5C/km with mid level lapse rates of 5.5 C/km to 6.5C/km while DCAPE is roughly in the 600 to 800 J/kg range. A few pulse type storms have developed and move across the area this afternoon and a strong to locally severe gust could occur with any storms that might manage to develop though given the minimal shear a lull in the activity is anticipated for eastern KY for the next several hours. The upper level trough axis should approach eastern KY this evening and tonight, crossing the area later Thursday into Thursday evening and then east of the area by late Thursday night. A cold front should precede this across the area from midday Thursday into early THursday evening, trialing from low pressure tracking across the Great Lakes to the St Lawrence Valley and Northeast through Thursday night. Meanwhile, a preceding shortwave trough in advance of the front has led to ongoing linear convection from IN and IL south into western KY. This should continue east per CAMS at least maintaining a cold pool with the activity likely to near the KCVG and northern KY area before sunset and perhaps reach the I-64 corridor counties near sunset while the southern portions of the linear convection should near the Lake Cumberland region a couple of hours later in the evening, progressing further east and southeast into the overnight hours. RAP has mid level lapse rates becoming slightly better over the next 6 hours at near 6C/km with some CAPE remaining tough some CIN will also begin to develop over the area by late evening. Effective wind shear should increase to 20 to 30KT at that time. Although there will be lesser instability over far eastern KY as compared to locations further west the threat for strong to damaging winds will linger, especially western portions of the area and possibly to the WV and VA borders. Shear will be slightly better from northwest of the I-64 corridor to west of Lake Cumberland and in those areas a brief spin up tornado cannot be completely ruled out with the liner convection/QLCS. The recent SPC Outlook has expanded the Slight Risk further into east KY while brushing the 3 northwestern counties with an enhanced risk. Torrential downpours remain a threat and areas that receive multiple rounds of stronger thunderstorms could experience high water or localized flash flooding. Following this prefrontal convection, renewed convection is anticipated ahead of the front on Thursday with some daytime heating. Some of this convection could also become strong and produce strong to locally damaging winds gusts. With the moist airmass remaining ahead of the front, torrential downpours will remain a threat and areas that receive multiple rounds of stronger thunderstorms could experience high water or localized flash flooding. Chances for showers and storms will diminish from northwest to southeast by late Thursday afternoon to early evening near and north of I-64 and near or just after sunset further southeast. Clearing skies with high pressure building in and slackening winds following recent rainfall should set the stage for fog formation perhaps not only in valleys but perhaps more widespread. Dense fog is also a possibility, but confidence was not high enough to mention dense just yet. .LONG TERM...(Friday through Wednesday) Issued at 330 PM EDT WED JUN 18 2025 The period is expected to begin with an upper level trough axis extending from Quebec to the mid Atlantic coast to the coast of the Carolinas an upper level ridging extending form the Gulf across the Southern Plains to northern Mexico while an upper level low should be nearing the Pacific Northwest with an associated trough moving into the western Conus. At that point a sfc ridge of high pressure is expected to be centered over northeast TN/Southern Appalachians while the boundary that will have crossed eastern KY during the short term period should have pushed into the Carolinas to northern GA. Meanwhile a frontal zone should generally extend from the St Lawrence Valley to the northern Great Lakes to northern Plains to MT at that point. The upper level ridge is expected to build north and northeast to end the week and into the weekend into the Lower to Middle MS Valley to Southeast/Appalachians to OH Valley, becoming centered over the Commonwealth with 594+ dm heights by late Sat over the state. Heights are expected to rise even further on Sunday with 596+ dm heights over much of the OH Valley and arts of the Central Appalachians by late Sunday. Meanwhile as the ridge builds in the eastern Conus, a trough should evolve over the western Conus to northern Plains regions. The upper level ridge is progged to begin to gradually weaken by Monday to Wednesday though ECMWF guidance generally remains stronger with the upper ridge centered over the Southern Appalachians at midweek while GFS guidance is weaker and more enlongated with the ridge from the OH Valley to the mid Atlantic states/portions of the northeast Coast. Meanwhile the one or more shortwave troughs should move from the northern Rockies/Northern Plains to the northern Great Lakes and toward the St Lawrence Valley. Lower height solutions would have weaker capping and more chances for diurnally driven convection while the recent ECMWF operational runs are drier solution. The consensus of guidance is for increasing heat from the weekend into the first half of next week with precipitation free weather through Monday. Heat indices should peak near or in excess of 100 by Monday to Wednesday. NBM probs as well as ENS and GEFS based probabilistic guidance have increasing chances for convection into midweek. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 200 PM EDT WED JUN 18 2025 At issuance time, MVFR was reported across much of the Commonwealth with some breaks in the clouds leading to VFR in a few areas such as KSYM initially. Some redevelopment of showers and storms has already begun with these leading to brief IFR to the lower end of MVFR. Overall, a trend toward VFR is anticipated with daytime heating and mixing during the first 3 to 6 hours of the period outside of convection where brief MVFR to IFR is anticipated. Within stronger showers and storms gusts to 30KT is also possible. A lull in the activity is expected for a couple of hours either side of 00Z with MVFR prevailing. However, one or more lines or areas of showers and storms should near the area by the 03Z to 06z timeframe with reductions to MVFR and IFR as it passes and gusty and erratic winds perhaps to 40KT in the strongest cells. An overall trend to prevailing MVFR should occur for the bulk of the area as the lower levels saturate and a cold front approaches during the last 12 hours of the period. Additional showers and storms are possible at times as well, especially before 12Z when brief lowering of ceilings are possible along with some strong and erratic gusts. && .JKL WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...JP LONG TERM...JP AVIATION...JP