Area Forecast Discussion
Issued by NWS Jackson, KY

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182 FXUS63 KJKL 220840 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 440 AM EDT SUN MAY 22 2016 .SHORT TERM...
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(Today through Monday) Issued at 425 AM EDT SUN MAY 22 2016 Early this morning, a trough extended from Eastern Canada south into the Eastern Conus. A ridge extended from Mexico north into the Plains and Upper MS Valley region, while a trough encompassed much of the Western Conus. A shortwave moving through the Eastern Conus trough is rotating away from the region at this time. However, another couple of shortwaves are dropping south into the Great Lakes region and Northeast Conus. Clouds have largely cleared across the region and fog has formed in some valley locations and some of the AWOS and ASOS sites around the region have reported dense fog at times. The main concern early this morning is the fog and dense fog across the region. Since skies have cleared over the vast majority of the area with the VA border counties being the exception and generally light winds are being reported outside of the highest terrain, the fog may become more widespread and dense toward dawn. A dense fog advisory remains in effect for the southwest portion of the CWA and trends will continue be monitored for any potential expansion of this over the next few hours. What fog develops should lift and dissipate through about 9 or 10 AM EDT or about 2 to 3 hours or so after sunrise. Otherwise, relatively cold air aloft and the shortwaves rotating down through the trough and generally passing to our east should combine with daytime heating for steepening lapse rates and a rather extensive CU field by this mid afternoon across the central and eastern portions of the CWA. Some showers should also develop and a thunderstorm or two cannot be ruled out. Rising heights are expected overnight tonight as the southern portion of the trough closes off to a closed low that meanders toward Eastern VA and the axis of the mid level ridge nears. At the same time, sfc high pressure will also build into the area. This should set the stage from clearing skies tonight along with slackening winds. Temperatures especially in valley locations should reach or fall below afternoon crossover temperatures anticipated to be in the mid to upper 40s and fog should develop again tonight. With some solar insolation today and drier air advecting in, confidence in the areal extent of the fog and whether or not it might become dense is not all that high. However, what dense fog that does develop will probably be across the eastern or southeaster valley locations. Daytime heating under the influence of the ridge should produce a CU field on Monday afternoon, especially across eastern sections of the area as the Slow moving upper low meandering toward the Mid Atlantic coast should bring or keep the atmosphere relatively moist near 850 mb. The airmass will moderate a bit as well with mid 70s in most areas. .LONG TERM...(Monday night through Saturday) Issued at 420 AM EDT SUN MAY 22 2016 A strong upper level closed low, along with surface low pressure, will be positioned just off the coast of the eastern Carolina`s as of 0z Tuesday, and should continue to ride up the Atlantic seaboard Monday night through Tuesday. As it slowly moves away, heights will begin increasing across the Commonwealth as steep upper level ridging moves in. At the surface, broad high pressure will take hold, allowing for mostly clear conditions, light and variable winds, and temperatures rising to near 80 degrees. By Tuesday night, a shortwave will move through the upper level ridging pattern. This, in addition to southerly winds tapping into warm...moist...unstable Gulf Coast air, will provide the ingredients necessary to invoke convective activity across the region beginning Wednesday and continuing through Wednesday night. Best instability for thunderstorm development will be during the afternoon and into the evening, before a surface inversion and decreasing lapse rates effectively cut off thunder potential between 3 and 6z Thursday. Several more shortwaves are expected to traverse KY for the latter half of the workweek. Continued southerly flow and warm/moist advection will keep precip chances in the forecast from Thursday through the weekend, with afternoon heating leading to thunderstorm concerns, followed by quick decreases in instability overnight. Unfortunately, model solutions lose considerable agreement between Friday and Saturday, so stuck with a model blend for pops from this point on, which generally keeps chance pops to round out the extended portion of the forecast. Each day during the extended should expect similar temperatures in the upper 70s and low 80s.
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&& .AVIATION...(For the 06Z TAFS through 06Z Sunday night) ISSUED AT 220 AM EDT SUN MAY 22 2016 The clearing form the west and northwest has led to improvement in CIGS to VFR as far southeast as JKL and SJS. However, dense fog has developed or been reported at least at times at SME and SYM with some indefinite ceilings. As clearing continues to move into to the remainder of the area, additional areas of dense fog should develop. At this time, dense fog is expected to also affect LOZ, JKL, and SYM at least briefly by 11Z. For now, we expect that drier air moving into the northwest should lead to improvement or at least limit dense fog at SYM. Improvement to VFR should occur in all locations 12z to 14z, however, daytime heating should steepened lapse rates and lead to redevelopment of a substantial CU field by 17Z along with the threat of some instability showers at SYM, SJS, and JKL. Winds will be generally be out of the west-northwest through the forecast period, averaging 10 kt or less. && .JKL Watches/Warnings/Advisories... Dense Fog Advisory until 9 AM EDT this morning for KYZ068-069- 079-080-083>085. && $$ SHORT TERM...JP LONG TERM...JMW AVIATION...JP

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