Area Forecast Discussion
Issued by NWS Jackson, KY

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261 FXUS63 KJKL 240837 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 437 AM EDT Tue Apr 24 2018 .SHORT TERM...(Today through Wednesday) Issued at 414 AM EDT TUE APR 24 2018 A strong 500mb low is currently making its way across western Kentucky and Tennessee, while the associated surface low is just slightly farther SE, moving into the Carolinas. The surface low is quite expansive, encompassing much of eastern TN as well at 12Z. This surface low will continue to strengthen throughout the day and into tonight as it moves NE across the Carolinas, reaching Virginia by 12Z Wednesday. The upper level low will shift just east of Kentucky by this point as well. After 12Z, the system will continue to ride up the eastern Atlantic seaboard, with the upper level low losing considerable strength as it becomes absorbed into a larger system over the lower Great Lakes. Meanwhile, broad high pressure will move southeastward, taking hold across Kentucky for the day Wednesday. As for sensible weather, despite light easterly winds at the surface, winds in the mid and upper levels will be due south, pulling ample moisture into the region and resulting in widespread rainfall through much of the day. There still looks to be a brief period in the late afternoon where soundings show enough instability during peak heating to produce a few rumbles of thunder. Ingredients are not overwhelming, however, especially as you head northward through the CWA, so did not go any higher than an isolated mention. QPF should generally be a half inch or lower through the day, but any heavier showers/thunderstorms could easily surpass this. Heading into the overnight, we start to see the system shift eastward and winds quickly transition to a more northward direction in the mid and upper levels, and NW in the lower levels. This will cut off some of the influx of moisture, however we will still be able to tap into wrap around moisture from the system, so expect continued scattered but light rain shower potential throughout the night. Did keep mention of numerous showers in the far SE portion of the state where upslope flow will play a large factor. By Wednesday, the system will continue to drift away from the region as drier high pressure takes hold from the west. Pops are expected to slowly diminish from west to east throughout the day, once again holding on the longest in the far SE with continued favored NW flow. Given the abundance of clouds and rain across the region, temperatures will be fairly uniform and mild. Highs both today and tomorrow will be in the low 60s, with overnight lows in the low 50s. .LONG TERM...(Wednesday night through Monday) Issued at 437 AM EDT TUE APR 24 2018 Whatever active weather there is during the period looks like it will be in the first few days. Light rain on the trailing edge of a storm system moving up the east coast could still be affecting our far eastern counties Wednesday evening, but will be on the way out. At least a brief break in precip is then expected into the day Thursday. By late Thursday, rain could again be in the picture from another upper low moving slowly across the southeast CONUS (the system currently over MT, WY, and the Dakotas). It`s uncertain how far north the rain will occur. The GFS and NAM both have light precip in our southern counties late Thursday into Thursday night, while the ECMWF keeps it to our south. Considering a similar model scenario played out in advance of the system currently bringing us rain, the American models will be given consideration and a chance POP will be carried near the TN border. Whatever plays out, the system is expected to depart Thursday night. After only a brief break, a cold front is expected to arrive Friday evening (supported by an upper level trough currently offshore of British Columbia). Moisture looks to be very meager, and the ECMWF is dry and the GFS only has very light precip in our far north. The situation does not seem to justify anything more than a slight chance of showers at the northern edge of the forecast area. After this, ridging at the surface and aloft is forecast to build into the area, resulting in dry weather Saturday through Monday, with highs nearing 80 by Monday. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 205 AM EDT TUE APR 24 2018 A storm system over the mid Mississippi Valley will meander eastward very slowly through the forecast period, expanding across eastern Tennessee through the day today. This will keep the threat of rain in the forecast. For the rest of the overnight, expect generally VFR conditions at the TAF sites as rain showers are a bit more scattered in nature across eastern Kentucky. The exception is south central Kentucky, including KSME, which will continue to see ongoing light rain through the overnight. Once we hit daybreak this morning, rain showers will be on the increase, bringing MVFR conditions to the TAF sites by this afternoon. Some of the heaviest showers could also result in brief IFR conditions as well. Isolated thunderstorms will be possible during the mid/late afternoon, though confidence on when and where these will set up remains quite low at this time. As we head into the evening, rain showers will begin to deteriorate and shift eastward, becoming more scattered in nature. However, as the best rain chances move out overnight, the CIGS and VIS (fog) will likely show a quick decreasing trend to IFR or lower to round out the TAF period. Winds will generally be light and variable under 10 knots through the period. The exception is KSYM which is still seeing some gusty conditions around 15 knots for the overnight, and KSJS which will continue to see some LLWS through a good portion of the overnight as well. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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