Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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856 FXUS63 KJKL 171050 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 650 AM EDT Wed Jul 17 2024 .KEY MESSAGES... - Showers and thunderstorms will impact the region through early next week, with the highest probability and greatest coverage today. - Some minor flooding of low-lying areas will also be possible through this evening, if storms pass repeatedly over the same locations. - A welcomed relief from the heat follows for Thursday through the middle of next week, with afternoon high temperatures in the upper 70s to lower 80s. && .UPDATE... Issued at 650 AM EDT WED JUL 17 2024 Made some refinements to PoPs for the next 24 hours based on latest radar trends and CAMS. Thunderstorms have developed ahead of a weak mid-level circulation that has developed overnight in association with the MCS activity over central Kentucky. The leading edge of this circulation is taking advantage of a weakly unstable atmosphere to produce the showers and thunderstorms. This activity will continue to move northeast through this morning across eastern and southeastern Kentucky. && .SHORT TERM...(Today through Thursday) Issued at 328 AM EDT WED JUL 17 2024 The models are in very good agreement through the short term regarding the upper level pattern and surface patterns. The trough will shift southeast with time, occupying the northeastern portion of the CONUS by early Thursday and spreading 500 mb height falls across the Ohio and Tennessee valleys today through Thursday. The surface cold front will gradually ease southeast, moving through the Commonwealth primarily late this afternoon through the overnight tonight. This will result in an active period of showers and thunderstorms across eastern Kentucky, providing beneficial rainfall to much of the area. A large MCS continues to push east and southeast across much of the Commonwealth early this morning. CAMS and SPC Mesoanalysis depict meager instability over areas mainly north of the Mountain Parkway, with greater instability towards the KY-80/Hal Rogers Parkway corridor, especially along and west of Interstate 75. Would thus expect new convection to develop at times along and ahead of the current MCS activity and impact southwestern and southern parts of the forecast area the remainder of this morning. Meanwhile, to the north of the Mountain Parkway would expect primarily rain with embedded heavier showers owing to the weaker instability this morning. By afternoon, the cold front will be moving southeast across the northern part of the forecast area. Any partial clearing along and to the south of the front will destabilize the atmosphere and allow for development of additional showers and thunderstorms. Much of the rain will be beneficial, but will need to monitor for training of the heaviest cells over any one area which may result in some localized flooding issues in low-lying areas. With the high humidity and cloud cover today, highs will be much cooler than in recent days, with highest temperatures in the south where clouds and convective activity may be able to hold off the longest. Convection will gradually diminish from northwest to southeast Wednesday night with the loss of heating and as the front eases off to our southeast. Lows will range from the mid to upper 60s. For Thursday, despite the front stalling well to the southeast of the region, the trailing upper trough will be moving southeast across the Ohio River Valley in the afternoon and early evening. Despite cooler surface temperatures, residual moisture and instability from steepening lapse rates aloft will result in a continued chance for afternoon showers and thunderstorms across the southeastern half of the forecast area. Temperatures will only reach the upper 70s to lower 80s across the area with cool dry air advecting in with surface high pressure nosing into the area from the north behind the cold front. .LONG TERM...(Thursday night through Tuesday) Issued at 415 AM EDT WED JUL 17 2024 The extended will start off with large scale trough aloft in place over the eastern CONUS east of the Rocky Mountains, with a cold front extending southward from northern New England, through the Mid-Atlantic region and into the Gulf Coast states and eventually the southern Plains. A surface low is progged to be in place over eastern Texas, with its own surface cold front extending across southern and western Texas Thursday night. A large ridge of high pressure is forecast to slowly push into the Ohio and Tennessee Valleys Thursday night through Friday night, and will bring dry weather to the area to finish out the week. A few showers and storms might push across the VA and TN borders into portions of southeastern KY Friday and Friday night, as a wave of low pressure moves eastward along the cold front that will be in place to our south. By early Saturday, a stronger wave of low pressure is forecast form along the western end of the cold front, and then move eastward along it. As the wave moves our way, it will cause the cold front to make a northward push over the weekend, bringing showers and storms to the area. Used a blend of the latest runs of the GFS, ECMWF, WPC analysis, and GFS Ensemble guidance to construct the forecast. We will see much better rain chances Sunday through Wednesday, as the subtropical high strengthens and expands westward toward the southeastern CONUS. As this occurs, the surface cold front will be pushed even further north. We will also see an increased flux of moisture into the region due to southerly flow from the offshore ridge. Waves of low pressure moving along the front will also act as triggers for showers and storms heading into the middle of next week. Now for some good news, it appears that temperatures through out the extended will be a few degrees below normal, as a cooler and less humid air mass moves into the region behind the cold front, as it moves off our south to start things off. In a nutshell, the first few days of the extended should be mostly dry, with high pressure mostly in control. From Sunday onward, however, the pattern will become quite active, with a northward moving cold front, waves of low pressure moving along it, and a westward expanding subtropical ridge combining to bring enhanced rain chances to eastern KY. As always, we will keep a close eye on the potential for locally heavy rain Sunday through Tuesday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 115 AM EDT WED JUL 17 2024 VFR conditions prevail for the most part, though pretty much all TAF sites will have at least brief periods of sub-VFR conditions in and near showers and thunderstorms, especially from late Wednesday morning into Wednesday evening, but also possibly at times during the remainder of the early morning hours this morning as a decaying convective system moves across parts of the area. The reductions to MVFR or lower may be more widespread near KSYM between 12Z and 18Z with anticipated greater coverage of convection. Generally light and variable winds are expected through 14Z outside of any thunderstorms, with southwest to west winds thereafter at generally less than 10KT with higher gusts in and near any storms. Winds should begin to shift to the northwest upon frontal passage from northwest to southeast later this afternoon through tonight. Fog will become at concern at most if not all TAF sites, especially after 03z Thu. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CMC SHORT TERM...CMC LONG TERM...AR AVIATION...CMC