Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 211748 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 148 PM EDT Tue Mar 21 2017 .UPDATE... Issued at 1157 AM EDT TUE MAR 21 2017 Temperatures have warmed into the mid 60s across far southern Kentucky to about 30-40 miles north of the Tennessee state line. Farther north into northeast Kentucky, a stratus deck has kept temperatures in the low 50s with no signs of this mixing out anytime soon. Have accordingly lowered high temperatures for this afternoon north of Mountain Parkway. May very well need to bump them near the Tennessee border given approaching mid-high clouds and stratus remain north/west through peak heating. As mixing continues across south central to southeastern Kentucky, at least up through about 2500 feet, frontal boundary and subsequent surface undulations should remain confined to the Volunteer state as high pressure builds into the Ohio Valley. Have therefore lowered PoPs to only maintain slight chance mention across southern Wayne to Bell Counties late this afternoon through this evening as elevated convection works southeast out of the Midwest and across the Tennessee Valley. Trends continue to point to showers/storms remaining south of the Commonwealth, so outside of any outflow boundaries from preexisting convection working into eastern Kentucky, mainly dry conditions should remain in play through the day. && .SHORT TERM...(Today through Wednesday) Issued at 435 AM EDT TUE MAR 21 2017 Convection near the cold front continues to move east southeast to southeast from near Manchester southeast into southwest Virginia. After a lull in lighting activity cloud top temps from GOES 16 test not yet operational imagery were near -51C with multiple cloud to ground lighting strikes in the southeast Leslie, southern Perry extreme western Letcher County and on into Harlan County near Cumberland and Black Mountain. These will probably exit into VA a bit earlier than the initial forecast grids per cloud top temp and radar trends. The cold front will continue to sag southeast before slowing down or stalling out over the TN Valley. The boundary should reside approximately near the I 40 corridor by midday. North of the boundary, a considerable amount clouds are expected, but very little if any convection is expected today. Convective allowing models which did not handle overnight convection well, develop convection near the vicinity of the confluence of the OH and TN Rivers and then track it along the boundary generally south of the area as a couple of surface waves of low pressure move along the boundary. There is some uncertainty as to how far the boundary will get before height falls associated with a shortwave trough to move across the OH Valley region this evening. Also, recent GFS and ECMWF have some weaker convection near the TN border during the evening. Locations further to the north should only experience an increase in clouds especially at mid and high levels as the shortwave moves through. Showers and possibly a couple of thunderstorms could affect parts of the Lake Cumberland region and the TN border during the evening and some slight chance to chance pops have been used during that time period in that area. Otherwise as one of the surface waves of low pressure reach the Carolinas and high pressure builds south from Ontario, the boundary will sag further south of the area with cold air advection in its wake anticipated along with a gradual decrease in clouds from north to south. Temperatures generally along and north of the I 64 corridor could fall to the freezing mark or just below tonight with lows mainly ranging through the 30s elsewhere. Locations along the TN border may not fall below 40 however. The high will bring colder and drier air into the region overnight and on Wednesday and below normal high temperatures are expected with the far north probably not reaching 45 and the far south climbing to about 55. This high and airmass will set the stage for a rather cold late March night to start the long term period. .LONG TERM...(Wednesday night through Monday) Issued at 401 AM EDT TUE MAR 21 2017 Fairly meridional pattern setting up through the long term period that will lead to multiple chances of precip. The period does begin with high pressure east of the region along the Mid Atlantic coast Wednesday night. There will be a period where decoupling and radiational cooling can occur early on before some mid to high clouds stream into the region. After this high pushes east as an upper level ridge will build across the region. This ridging the return flow around the surface high will put us securely in the warm sector by Thursday. This will lead spring like temperatures through most of the period. Then we focus attention on vertically stacked system ejecting out of the Front Range Friday and moving into the Ohio and Tennessee Valleys Saturday into Sunday. There remains some timing differences and therefore kept close to the blended guidance. However did opt to cap POPs at likely given the timing uncertainty at this point. Also in terms of storms it does look like we get cutoff from better instability by convection along and near the Gulf coast. This seems reasonable given this lines up well with SPC severe probability climatology for this time of year. Overall looks like QPE of around 0.75 inches is possible Saturday into Sunday night. There could be a few showers Monday wrapping around surface low, but ridging will build east ahead of next upper level trough. && .AVIATION...
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(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 148 PM EDT TUE MAR 21 2017 Stratus continues to hold strong this afternoon, mainly along of and north of Mountain Parkway. Have begun to see this mix out slightly with LOZ/SME returning to VFR criteria while JKL/SJS/SYM remain socked in underneath MVFR ceilings. All terminals should return to VFR levels by late this afternoon as mixing continues and a frontal boundary, currently along the Kentucky/Tennessee border, edges southward ahead of drier air filtering in from the north. Increasing pressure as this occurs will allow for an uptick in northerly winds to near 10 knots tonight as ceilings lift. Pilots heading south toward TYS/BNA/MEM/ATL need to be on the lookout for thunderstorms later this afternoon and this evening. CB chances currently look to remain south of much of the Kentucky airspace, with a stray shower/storm possible near the Tennessee border.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GUSEMAN SHORT TERM...JP LONG TERM...DJ AVIATION...GUSEMAN is the U.S. government's official web portal to all federal, state and local government web resources and services.