Area Forecast Discussion
Issued by NWS Jackson, KY

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085 FXUS63 KJKL 132111 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 411 PM EST Wed Dec 13 2017 .SHORT TERM...(This evening through Thursday night) Issued at 404 PM EST WED DEC 13 2017 A potent clipper type system was moving southeast across the Midwest today, headed for the upper Ohio Valley by late tonight. It is bringing an increasing pressure gradient and warm air advection to Kentucky this afternoon. An increase in mid level moisture was resulting in radar returns moving over the area, but very dry low levels were resulting in virga. Despite the combination of wind and dry air, verification for the RFW has been hard to find. Much of the area has seen RH below 25%, but the 20 ft winds above 15 mph have been much more limited so far, and not coincident with the lowest RH. There is still time for winds to pick up more by early evening, and the RFW will be left to ride. If conditions do not materialize, it`s possible it could be lifted early. During the night, the clipper system`s cold front will pass through. With a return to cold air advection, the low levels will moisten in the upslope flow once again, and low clouds should develop. If the top of the convective moist layer can reach cold enough levels, we could see some flurries, but forecast soundings look marginal for this. Have included a chance in all but our far southwest counties for late tonight into Thursday morning. The system quickly departs to the east on Thursday and a weak surface ridge will build in from the west. Cold air advection will ease and become more neutral, and the moisture in forecast soundings become very shallow. We should see low clouds start to break up, but whether or not the whole area sees it by the end of the day is uncertain. High clouds will start to thicken during the day, which would limit sunshine even where low clouds do scatter out. .LONG TERM...(Friday through Wednesday) Issued at 411 PM EST WED DEC 13 2017 The extended portion of the forecast begins on Friday with an amplified upper level pattern in place with a stout ridge in the western CONUS transitioning to a trough in the east. On Friday, a decent short wave passes through the OH Valley but current model trends keep the majority of the lift and moisture to the north of the CWA so Friday will remain dry in addition to Saturday as a weak ridge quickly passes through the area. The upper level pattern transitions to a more progressive through the weekend before the next system develops with a stronger shortwave diving to the south and developing over the lower MS Valley area. This combined with another wave passing to the north. This set up will bring a much needed surge of moisture northward with precip developing into eastern Kentucky by Sunday morning and lasting into Monday evening. Concerning the top down of Sunday morning. At this point, surface temps will be border line for any sleet or freezing rain development. It appears with surface temps warming up ahead for this event, will keep a snow and rain mix in the morning hours and warming quickly into the late morning hours. Thus, will not expect any accumulation as well. With the drier pattern taking over again and the main storm track remaining to the north, the last two days of the extended will likely be dry at this point. This is especially the case with the outlooks and climatology. The last half of the extended looks to be at or just above normal as well. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 200 PM EST WED DEC 13 2017 Breezy VFR conditions will prevail into this evening. Southwest winds gusting 20-25 kts should be common by late today. A cold front will pass through tonight and winds will veer toward the northwest. Winds will gradually ease later tonight. An MVFR ceiling is expected to develop from northwest to southeast behind the front between about 04z and 07z and persist through the rest of the period. && .JKL WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM EST this evening for KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. Lake Wind Advisory until midnight EST tonight for KYZ051-052-060- 079-080-083>085-106. && $$ SHORT TERM...HAL LONG TERM...SHALLENBERGER AVIATION...HAL

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