Area Forecast Discussion
Issued by NWS Jackson, KY

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814 FXUS63 KJKL 221330 AAA AFDJKL Area Forecast Discussion...UPDATED National Weather Service Jackson KY 930 AM EDT SUN MAY 22 2016 .UPDATE... Issued at 930 AM EDT SUN MAY 22 2016 13z SFC analysis shows high pressure building into the state from the west. The drier air associated with this is also helping to clear out the clouds, though lingering fog lifting will slow that process for an hour or so. The dense fog has cleared out with just some patchy spots left behind. This will all be gone by 10 am with mostly sunny skies through the morning hours. However, we are still looking for a chance of showers and thunderstorms in our far east later today in concordance with the latest HRRR and NAM12. Currently, temperatures are varying from the low 50s where the fog is just clearing to upper 50s in places enjoying full sunshine. Dewpoints, meanwhile are generally in the low to mid 50s with light winds from the northwest. Added some of the latest ensemble model data from the ShortBlend and adjusted these per the latest obs and trends. These updated grids have been sent to the NDFD and web servers along with a conclusion of the NPW and freshened HWO/ZFP. UPDATE Issued at 802 AM EDT SUN MAY 22 2016 Hourly grids have been freshened up based on recent observations as well as satellite trends mainly to update temps...dewpoints...and sky. This led to no substantial changes...however. && .SHORT TERM...(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. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 803 AM EDT SUN MAY 22 2016 Fog or low some cases such as at SME and LOZ down to airport minimums should improve to vfr by the 13Z to 14Z timeframe. Daytime heating should steepen 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. Thunder cannot be completely ruled out...with these...but confidence and probabilities were too low to include in the TAF attm. Fog should again develop late in the period...but is not expected to bring reductions below MVFR at the TAF sites. Winds should average at 10 kt or less mainly out of the north to northwest. && .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...JMW AVIATION...JP is the U.S. government's official web portal to all federal, state and local government web resources and services.