Area Forecast Discussion
Issued by NWS Jackson, KY

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374 FXUS63 KJKL 251455 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1055 AM EDT Tue Oct 25 2016 .UPDATE... Issued at 1055 AM EDT TUE OCT 25 2016 14z sfc analysis shows high pressure sliding by to the north of Kentucky. This high, along with light to calm winds, settling quicker than anticipated originally, and clear skies through the night led to another cold morning with frost reported in some of the valley locations, along with some areas of dense fog along the rivers. The fog has cleared off now and temperatures are rebounding with near full sunshine back up through the 40s and into the lower 50s. Dewpoints, meanwhile, are generally in the lower 40s and winds still light. Have updated the forecast to fine tune the T and Td grids through the afternoon - incorporating the latest ShortBlend guidance along with current obs and trends. These have been sent out to the NDFD and web servers. A zone update, mainly to remove the dense valley fog wording was also issued. UPDATE Issued at 657 AM EDT TUE OCT 25 2016 Drier air is starting down across the higher terrain with the dewpoint at Black Mountain now down to 28 and falling quickly now. This should be the start of mixing down the drier air as we go through the day today. RH`s look to bottom out between 20 and 30 percent under sunny skies. Fortunately, winds will be rather light today, to limit the fire danger. Based on the fog channel, it looks like the fog is most prevalent in the eastern valleys, and forecast has this covered well. No changes warranted this morning except to freshen up temperature and dewpoint grids. && .SHORT TERM...(Today through Wednesday) Issued at 300 AM EDT TUE OCT 25 2016 Mid level ridge axis will slowly work eastward over the next 24 to 36 hours, keeping our weather dry through Wednesday. Temperatures have settled into the 30s in the colder valley locations early this morning. Despite the chilly start to the day, afternoon highs should rebound nicely with 850mb temperatures a degree or two higher than yesterday. This will put highs generally into the mid 60s across northern Kentucky to around 70 in southern Kentucky. Model soundings show some very dry air just off the surface that will likely mix down into the afternoon and evening hours with dewpoints crashing to around 30. While the ridge will start to move east of the area tonight, we should remain under its influence and would expect at a minimum for valley locations to decouple. Given the drier air in place, it seems reasonable that a few of the eastern valleys could approach the freezing mark. However, it appears temperatures for most will stay in the mid to upper 30s with lower 40s on the ridges. While temperatures may stay above cross over temperatures tonight, limiting fog or frost formation, we are close enough to freezing in some of our far eastern valleys to include a mention of some patchy frost late tonight. By Wednesday, heights continue to build with 850mb temperatures warming to just over +12C. This would support highs into the low to mid 70s, making for another beautiful eastern Kentucky fall day. Went slightly under guidance for dewpoints on Wednesday as models are bringing moisture back into the area much too fast, despite the southwest winds. .LONG TERM...(Wednesday night through Monday) Issued at 356 AM EDT TUE OCT 25 2016 An upper trough axis will swing through the Great Lakes to Tennessee Valley Wednesday night, as a surface low tracks across the upper Ohio Valley and lower Great Lakes. Moisture from the Gulf of Mexico will advect into eastern Kentucky downstream of these features as an attendant cold front moves toward the lower Ohio Valley, bringing a chance for showers to the Bluegrass region near or shortly after midnight. Have inserted isolated thunder mention at this juncture as elevated instability continues to look to be present with MUCAPE values of a few hundred J/kg. Surface-based instability of 500-1000 J/kg may be realized Thursday afternoon ahead of the cool front before a secondary surge of energy across the lower Great Lakes along with a surface ridge building into the Ohio Valley push the front into eastern Kentucky. Deep layer shear of 25-35 knots through the afternoon may be enough to generate a couple of sustained/organized updrafts, capable of producing gusty downdraft winds underneath any shower or storm. High pressure parking overhead will lead to a crisp Friday morning as valley temperatures bottom out in the mid-upper 30s with ridgetops remaining in the low-mid 40s. However, a quick return of warm air advection will take place Friday morning/afternoon as an upper high builds across Texas with anticyclonic flow stretching through eastern Kentucky. Following high temperatures in the mid-upper 60s Thursday, Friday looks to potentially be the beginning of a prolonged warm period as highs climb into the upper 60s to mid 70s. Upper ridging looks to continue to meander much of the Gulf of Mexico through the Mississippi Valley and Great Plains through the weekend as northern stream energy traverses south central to southeastern Canada into the northern United States. Current trends have pointed toward warm and dry conditions remaining in place for the most part across eastern Kentucky into next week, but will have to monitor southern extent/strength of aforementioned energy regarding sensible weather locally. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 657 AM EDT TUE OCT 25 2016 Mainly VFR conditions and light winds will be seen through Tuesday night. Some patchy dense valley fog is expected early this morning, but should not impact the TAF sites. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...KAS LONG TERM...GUSEMAN AVIATION...KAS is the U.S. government's official web portal to all federal, state and local government web resources and services.