Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 230220 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 1020 PM EDT SUN MAY 22 2016 .UPDATE...
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Issued at 1020 PM EDT SUN MAY 22 2016 Radar trends indicate that the boundary layer has finally begun to stabilize. Updated the forecast package to remove thunder. Also took the opportunity to freshen up the zones and to lower overnight lows slightly...mainly for a few spots in our east. Hourly obs are already showing temps approaching advertised lows in a few locations. Very dry air has managed to settle into the area with afternoon dew points dropping into the lower to mid 40s and this will help mitigate overnight fog potential. Dew points are higher in areas that saw rainfall this evening and as such expect any overnight fog to develop in these areas first. Would also expect those areas that received rainfall may even see some locally dense fog. However, attm felt threat wasn`t widespread enough to highlight but will monitor and pass on any concerns to incoming shift. UPDATE Issued at 822 PM EDT SUN MAY 22 2016 Convection continues to fire this evening across mainly our eastern most counties. High res, short term models do not show any definitive decrease in activity until after sunset. Based on current radar trends this seems reasonable. Current forecast has everything handled well. Updated grids to bring them in line with hourly trends. No updates to the zones attm.
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&& .SHORT TERM...(This evening through Monday night) Issued at 330 PM EDT SUN MAY 22 2016 19z SFC analysis shows low pressure just off to the east of Kentucky with high pressure building in from the west. This high is bringing some drier air to eastern Kentucky, but not quick enough to prevent the formation of instability CU and some light showers in the far east. Thunder has developed further east in West Virginia with some healthier showers. The latest near term models still predict some convective development in the far east through the first part of the evening. Plenty of sunshine at the start of the day, until the CU developed, helped send temperatures into the low and mid 70s across the area this afternoon. Dewpoints mixed down into the low to mid 40s most places, as well. This deep mixing is allowing some gustiness to develop with the northwest to north winds over the western parts of the CWA where gusts are reaching to between 15 and 20 mph. Elsewhere, northwest winds of around 10 mph are common. The models are in good agreement aloft through the short term portion of the forecast as they all pivot the eastern trough southeast and off the coast of North Carolina by midday Monday. This now closed low then lifts north along the coast into Tuesday morning while heights rebound for Kentucky and even some ridging works into the western parts of the Ohio Valley. Given the model agreement have favored a general blend for weather details with a lean toward the HRRR and NAM12 this evening and on through the night. Sensible weather will feature a small chance for scattered showers and stray thunderstorms over the far eastern tip of Kentucky through sunset. Otherwise, skies will be mostly clear overnight facilitating the development of a small to moderate ridge to valley temperature split along with valley fog - locally dense. The fog may become more extensive in the far east for places that manage to see any rain in the late afternoon/early evening. For Monday, another great day of weather will be on tap with temperatures hitting the low to mid 70s again along with comfortable humidity levels and plenty of sunshine for most of the area. Look for some extra clouds around in the far east as the high will only make limited progress east into Monday and more CU is expected to develop there by mid to late afternoon. Expect a similar night Monday night to tonight with another moderate ridge to valley temp split on tap along with patchy valley fog, probably less extensive than Monday morning thanks to another full day of drying. Again started with the ShortBlend for most elements of the forecast with some terrain adjustments to temperatures both tonight and Monday night for ridge to valley splits. During the latter part of the forecast the SuperBlend was used as the init with only minor adjustments to sky cover and temps/dewpoints. .LONG TERM...(Tuesday through Sunday) Issued at 400 PM EDT SUN MAY 22 2016 Broadening and deamplifying upper ridging will move overhead Tuesday as a surface ridge slides across the southern Appalachians toward the Atlantic coast. A continued warming trend will ensue as highs soar into the upper 70s to lower 80s as a dry airmass remains in place. An upper low across lower Alberta and Saskatchewan into the northern U.S, with an associated trough extending through the intermountain west into the Great Basin, will then begin to nudge eastward by midweek. Backing flow aloft along with leeside cyclogenesis across the Great Plains will bring a steady dose of return flow into eastern Kentucky. Showers and thunderstorms will be possible as early as Wednesday morning across the Bluegrass region into the Lake Cumberland region, but will likely hold off until later in the afternoon or evening when a shortwave impulse approaches the region. May very well see additional waves or changes in the timing to this one which could spark scattered storms Wednesday given warm sector positioning. Storm chances will continue through the remainder of the week into the weekend with a stagnant airmass in place, but any source of low level forcing in terms of a front will likely hang up well northwest of the Ohio Valley as parent upper forcing turns north near or west of the Great Lakes. A fairly sharp west to east gradient in precipitation coverage could occur as an upper ridge now looks to build across the eastern U.S. by late week into the weekend. Areas along the higher terrain of far eastern Kentucky would still likely see isolated storms due to orographic lift, but larger scale synoptic forcing could be minimal to nil. Will have to wait and see if the upper low lifting near the Great Lakes can turn east and bring any more widespread showers and storms into next weekend. Temperatures will continue to ride above normal with highs generally in the low 80s and lows in the low 60s. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 822 PM EDT SUN MAY 22 2016 Convection continues to fire this evening across mainly our eastern most counties. High res, short term models do not show any definitive decrease in activity until after sunset. A few thunderstorms have fired north of SJS within the last several minutes and these cells are moving towards SJS. Consequently updated the forecast to reflect VCTS for an hour or two. Otherwise, convection is expected to die down after sunset. With much drier air within the boundary layer, fog is not expected to be as prevalent tonight as it was this morning. Thus fog should develop late tonight mainly in the river valleys where there is a better source of moisture. But fog is not expected to bring reductions below VFR for any extended periods of time at our forecast terminals. SME`s relative river valley locations makes it most prone to any fog that does develop. Winds will be light but generally out of the north-northeast through the period. && .JKL Watches/Warnings/Advisories...None. && $$ UPDATE...RAY SHORT TERM...GREIF LONG TERM...GUSEMAN AVIATION...RAY

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