Area Forecast Discussion
Issued by NWS Jackson, KY

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798 FXUS63 KJKL 232324 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 724 PM EDT Wed Aug 23 2017 .SHORT TERM...(This evening through Thursday night) Issued at 256 PM EDT WED AUG 23 2017 High pressure will build east over the region and continue to influence our weather through Thursday night. This will keep skies generally clear with light winds. The drier air has been a bit slower than anticipated to work into eastern Kentucky today and given the higher than expected moisture going into tonight, we can expect to see some pretty robust fog development in the valleys tonight. Fog will likely become dense at times in the valleys and will toss in a mention into the HWO. While drier air should mix down tomorrow afternoon, should still see some pretty decent fog again for Thursday night, which is not all that uncommon for this time of year. Overnight lows each night will dip into the 50s, but the cooler night will likely be Thursday night with the drier air in place going into the overnight period. This could allow us to threaten a few record lows Thursday night. .LONG TERM...(Friday through Wednesday) Issued at 325 PM EDT WED AUG 23 2017 The models, with the exception of the CMC, are in pretty good agreement with the longwave pattern aloft through the extended portion of the forecast. They all depict the broad northeast trough slowly easing away from the area while troughing associated with `Harvey` moves onshore over the western Gulf of Mexico through the start of the weekend. This will place eastern Kentucky under the influence of northwest flow with only weak bits of energy passing through in the mid levels. Additional troughing will take shape to the northwest of the area at the start of the new work week while most models keep the upper low associated with Harvey`s remnants stuck to the Texas coast. This becomes the main concern and confidence crusher in the forecast going forward. Should `Harvey` remain in place - woe to the western Gulf Coast - Kentucky will be shielded from its influence by building heights locally. That is, at least until the developing upper low from the west moves closer as we head deeper into the week - perhaps luring more of Harvey`s upper support northeast into the Lower Mississippi Valley and Deep South. However, with the agreement of the GFS and ECMWF will lean toward the idea that through the extended the core of the tropical storm remains to our southwest and hold off its major impacts on our weather. Sensible weather will feature beautiful weather through at least Sunday with cool temperatures for this time of year and limited showers or thunderstorm chances as sfc high pressure holds on over the area. The forecast gets more murky for Monday through Wednesday with shower and thunderstorm chances still mainly driven by the diurnal cycle. However, this could change dramatically if the upper low to the southwest actually gets picked up and starts to move east sooner than the blends suggest. Heavy rains from this are still a concern for the area in the latter part of the forecast, though the models are favoring a less impactful scenario. Made mainly mostly terrain based adjustments to the lows each night, though the higher PoPs later in the forecast should limit the ridge to valley differences. Also, adjusted the PoPs to gear them more toward a diurnal cycle than initially represented by the SuperBlend. && .AVIATION...
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(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 724 PM EDT WED AUG 23 2017 An area of surface high pressure will continue to build across eastern KY tonight. This is leading to general NW flow and some drier air continues to spill southeast. The mostly clear skies will combine with above elements for fog development especially in the valleys and some of this could be dense at times. That said, did opt to keep IFR to MVFR fog at most sites toward dawn, with SJS the lowest given the tendency for lower VIS in northerly flow patterns. This will lift around 13Z to 14Z for most and VFR conditions return for all sites through the rest of the period. The winds will remain light and generally northerly flow.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KAS LONG TERM...GREIF AVIATION...DJ is the U.S. government's official web portal to all federal, state and local government web resources and services.