Area Forecast Discussion
Issued by NWS Jackson, KY

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002 FXUS63 KJKL 161833 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 133 PM EST Tue Jan 16 2018 .UPDATE... Issued at 1203 PM EST TUE JAN 16 2018 Snow has overspread all of eastern Kentucky into this morning. Reports have been coming in from around an inch to near 4 inches in places. The latest higher resolution model guidance continues to show light snow, with embedded pockets of moderate snow only gradually shifting off to the southeast through the rest of this afternoon. A band of heavier snow has fallen generally along and west of a line from Irvine to Mount Vernon, to Monticello, with 2 to 4 inches reported already. Given the additional 1 to 2 inches through the rest of the day, went ahead and included a row of counties in a warning. Bumped up the rest of the area in general, with most locations receiving 2 to 4 inches by early this evening. Have also extended the advisory up north through 7 pm, given the slower diminishment of the snow. Updates have been sent. UPDATE Issued at 755 AM EST TUE JAN 16 2018 Adjustments have been made to hourly temperature, dewpoint, and wind grids. The previous pops and sky generally had the timing covered. The heavier bands of snow appear to be somewhat transient, but will need to be monitored today. Additional snowfall today should mainly be in the 1-3 inch range for most areas. Along and north of I-64, snow should be the lightest closer to 1 inch with locally 4" possible mainly above 2000 feet elevation. The southeast counties where snow is arriving at this time should experience road conditions deteriorate over the next couple of hours. && .SHORT TERM...(Today through Wednesday) Issued at 405 AM EST TUE JAN 16 2018 ...Accumulating Snow Slowly Spreading Southeast Across East KY... Early this morning, a trough extended from Eastern Canad south into the eastern Conus. Within this trough, an upper level low was centered over the Great Lakes region with a shortwave trough rotating around it still digging south through the MS Valley. Further west, a ridge extended through the Rockies with a trough approaching the U.S. west coast. At the surface, an arctic boundary continues to sag south and southeast across East KY and is currently over the southeastern counties. Southeastern valley locations are generally in the low 30s with teens and 20s over northeast and Central Ky and some single digits in the west. A slow moving band of steadier snow that has been moderate to heavy at times has arrived across the counties north of the Mtn Parkway. The heaviest snow has been across parts of central Ky near I 65 south into parts of western and middle TN. The cold front should continue to slowly sag south across the area with the slow movement of the boundary and the post frontal band of snow slow due to the still digging shortwave. However, this shortwave should begin moving more to the east through this morning with the through trending toward more neutral. This should lead to the boundary continuing to slowly move east with a surface wave or two likely moving along it while deeper moisture persist much of the day across East KY lingering into the evening in the southeast. Also, a jet steak moving through the OH Valley to northeast should put much of the region in deeper lift when combined with the lift from the approaching shortwave. The forecast soundings trend closer to becoming isothermal nearer to -10C this morning and into the afternoon across the south and southeast. Thus, the combination of this, the deeper lift and substantial omega for a while in the DGZ will probably lead to higher snow to liquid ratios from later this morning into this evening and a bit more snow than the previous forecast. As the shortwave starts to move east and approach, the steadier moderate to at times heavy snow should continue pushing south and east, possibly not arriving at the VA border until as late as 10 AM. The steadier snow should end this morning near I-64 and north though the steadier snow will persist longer in the southeast, especially near to the VA border. With the slower onset and recent model trends of accumulating snow lingering in the far southeast and near the VA border until late this evening the end times some adjustments have been made to the end times of the winter weather advisory. Rowan County has been added a segment for the bulk of the area through 0Z this evening. Pike, Harlan, and Letcher counties will experience the latest arriving snow and latest end to the steadier snow and have been extended until midnight tonight. Once the steadier snow departs, some isolated snow showers and flurries will likely linger through some breaks in the clouds may continue in the cold advection pattern. Lows for the entire area should be in the single digits above zero although where decoupling may occur with fresh fluffy snowpack, a cold spot or two could hit zero or even a degree or two below. Low level moisture should linger through the end of the period and until or a while after the 500 mb trough axis moves through the region, the threat for isolated snow showers or flurries leading to some fluffy dusting to half inch amounts will continue into the day on Wednesday. Highs will be well below normal on Wednesday with the coldest temperatures in the southeast where the 850 mb temperatures will be colder through the day and clouds and isolated snow showers and flurries should be most persistent. .LONG TERM...(Wednesday night through Monday) Issued at 304 AM EST TUE JAN 16 2018 The extended period will be mostly dry, with cold temperatures to start, and then a warming trend expected for the latter part of the period. Bitterly cold temperatures will persist across the area Wednesday night through Thursday night, with lows expected to bottom out in the upper single digits and lowers teens Wednesday morning, and in from the mid teens to the lower 20s on Thursday morning. The warm up will first begin on Thursday, as a previously cold air mass begins to modify after a period of persist south and southwest winds. Highs on Thursday will only be in the 30s across the area, but most locations will be above freezing, which will feel quite warm compared to the bitter cold we will see across the area Tuesday night through Wednesday night. Friday will mark the true warm up, as the persistent southerly winds allow the mercury to climb into the low to mid 40s across the area. The weekend looks to be even warmer, as mostly clear skies and continued southerly winds allow the air mass that will be in place to warm even more. Highs on Saturday should easily max out in the low to mid 50s, while on Sunday we could see highs ranging from the mid 50s to lower 60s across eastern Kentucky. The southerly winds and warming conditions will be harbingers of an area of low pressure that will be our next weather maker. We could see rain showers moving into the area by early Sunday morning, as the weather system makes its way eastward across the region. The showers will be isolated to scattered at first, but will become more widespread Sunday night and Monday, as a cold front moves across the area. The latest model data suggests that this rain will persist until early Monday night before finally exiting the area. && .AVIATION...
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(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 133 PM EST TUE JAN 16 2018 Light snow and IFR conditions will gradually improve from northwest to southeast through this evening. Expect MVFR ceilings to remain in place through the rest of the period, with intermittent flurries/isolated snow showers continuing across the area. Northwest winds of 5 to 10 kts will continue through the period as well.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 7 PM EST this evening for KYZ044- 050>052-059-060-080-084>087-104-106>117-119. Winter Storm Warning until 7 PM EST this evening for KYZ058-068- 069-079-083. Winter Weather Advisory until midnight EST tonight for KYZ088- 118-120. && $$ UPDATE...GEOGERIAN SHORT TERM...JP LONG TERM...AR AVIATION...GEOGERIAN is the U.S. government's official web portal to all federal, state and local government web resources and services.