Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 160556 AAC AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 156 AM EDT Mon Oct 16 2017 .UPDATE...
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Issued at 147 AM EDT MON OCT 16 2017 Hourly grids have been freshened up based on recent observations and trends. Breaks in the low clouds have been noted on satellite imagery over parts of western OH and Indiana. There were no substantial changes at this time other than adjustments to sky cover in the north based on recent trends. Northwest winds will continue overnight, advecting in a colder and drier airmass behind the cold front that moved through on Sunday evening. UPDATE Issued at 1019 PM EDT SUN OCT 15 2017 Cold front has cleared eastern Kentucky. However, the H850 trough is only about 125 miles behind the surface front, following close behind and now moving to the southeast across our area. This feature is kicking off a second band of showers which is currently moving across our southwestern zones. HRRR has picked up on this new development and brings it east-northeast across the southeastern half of our forecast area over the next several hours, though weakening with time. Consequently had to adjust PoPs to account for this activity. Also made adjustments to the temps and dew points as the cooler, drier air appears to be moving in more rapidly than originally forecast, again the result of the H850 trough which is typically a useful feature for timing the more credible cooler and drier air into some given region. UPDATE Issued at 759 PM EDT SUN OCT 15 2017 Strong, fast moving cold front is a little more than half way through the forecast area. Expectations are that it will exit eastern Kentucky between 9 and 10 p.m. this evening. Winds along and just behind the front have been gusting as high as 40-45 mph through the late afternoon and early evening. But there seems to have been a decreasing trend over the last hour or so. There has also been some isolated thunder through the evening as well. But the threat of thunder should end in the next hour or so. Frontal boundary will continue to push east overnight as northwesterly winds gradually drop off. Clouds will also linger until closer to dawn. Adjusted PoPs, sfc temps and dew points for the early evening update, mainly in an attempt to better capture changes in sensible elements associated with the frontal zone as it pushes across the area.
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&& .SHORT TERM...(This evening through Monday night) Issued at 317 PM EDT SUN OCT 15 2017 A broken line of showers well ahead of the approaching cold front is moving across the area. The lack of instability has limited the strength of the convection, but instability is a little greater in the southwest part of the area where 18Z SPC mesoanalysis has CAPE over 1000 j/kg. Some lightning has shown up southwest of the forecast area in far northern TN near the KY border so will continue to carry a slight chance of thunder for the next few hours. Other scattered showers are near the front which has passed SDF and CVG. There are some gusty winds with the front with a peak wind of 36 knots at CVG and 39 knots at SDF. The front will move quickly southeast across the area late this afternoon and early evening and be southeast of KY by around 00Z. The shower chance will diminish quickly after the frontal passage and much cooler air will spread into the area. While fog will likely limit frost formation Monday night, there may still be some scattered frost in some areas. .LONG TERM...(Tuesday through Sunday) Issued at 317 PM EDT SUN OCT 15 2017 There is good model agreement with the evolution of the overall upper level flow across the United States during the coming week. Initially there will be weak troughing in the east, and weak ridging over the southwest U.S. This will transition to a slightly wavy zonal flow, but by the end of the week as troughing develops in the west, upper ridging will build in the east. Overall this means an extended period of dry weather for us, with warming temperatures. At the beginning of the period we will still be under the influence of the cool air mass which will overspread the area Sunday night, and frost remains a possibility in a few spots Wednesday morning. However on Tuesday the surface high will begin a gradual shift to the east and this will combine with a building upper level ridge late in the week to bring a warming trend, with temperatures well above normal by the end of the week. Very warm weather will continue through next weekend with readings around 10 degrees above normal. && .AVIATION...
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(For the 06Z TAFS through 06Z Monday night) ISSUED AT 158 AM EDT MON OCT 16 2017 Drier air continues to advect into the region on NW flow behind a cold front as high pressure begins to build into the region. Showers have diminished with generally MVFR CIGS remaining in the south and generally VFR CIGS observed in the north. At this point have improved SYM to VFR through the period with VFR CIGS prevailing at SJS within the next hour or two. Further south, have timed in an improvement to VFR that is more based on upstream obs and more optimistic compared to guidance. The stratocu and cumulus should lift into thin CU and mix out on Monday, so once a location improves to VFR, VFR should prevail through the end of the period. North northwest to north winds at 10KT or less should prevail through the 22Z to 00Z window, before slackening as the center of the high nears.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...SBH LONG TERM...SBH AVIATION...JP is the U.S. government's official web portal to all federal, state and local government web resources and services.