Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 191100 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 700 AM EDT Sun Mar 19 2017 .UPDATE...
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Issued at 700 AM EDT SUN MAR 19 2017 The forecast was on track so far this morning. The latest obs were ingested into the hourly forecast grids to establish new trends, but no major changes to the forecast were needed.
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&& .SHORT TERM...(Today through Monday) Issued at 302 AM EDT SUN MAR 19 2017 The majority of the short term period should be mild and dry, as a ridge of high pressure settles over the region. Cloud cover will be fairly widespread early this morning, but will slowly erode from southwest to northeast today, as the ridge begins to expand eastward. This clearing trend is then expected to continue through late this afternoon, with mostly clear skies anticipated across the entire area by early this evening. Light winds will prevail through out the period as well, generally out of the north today at less than 5 mph. The winds should shift around to the east and then south late tonight, as an area of low pressure and its associated surface front approach from the north. The light winds and clear conditions tonight will set the stage for fairly well defined ridge and valley temperature differences. Our valleys should easily fall into the upper 20s overnight, setting the stage for a frost event. The ridgetops around the area will also be cold, but with slightly warmer minimum values in the low to mid 30s. Some frost will also be possible on ridgetops, but the most widespread frost should be confined to the deepest and most sheltered valleys. High temperatures today look to be a bit below normal, with max readings ranging from the upper 40s north of the Mountain Parkway to the lower 50s south of the parkway, due to the presence of cloud cover and northerly flow during part of the day. A nice warm up is likely in store for Monday, as southerly winds become more well established and increase in intensity slightly. The anticipated good sunshine and southerly flow should allow temperatures to max out in the lower to mid 60s across the area. Toward the end of the period, Monday afternoon to be exact, there will be rain chances coming back into the picture for eastern Kentucky. However, the latest model data is all suggesting that the trough of low pressure and its surface front will be slowing down a bit compared to earlier model runs, probably due to a slightly strong ridge developing across the region. That being said, decided to slow down the onset of precipitation on Monday by several hours. The new forecast will feature the first precipitation moving into eastern Kentucky between 18 and 19Z, as opposed to late Monday morning as was previously forecast. This precipitation should expand slowly southward Monday afternoon, as a cold front moves southward through the Ohio River Valley. .LONG TERM...(Monday night through Saturday) Issued at 440 AM EDT SUN MAR 19 2017 The 0Z models runs continue to be fairly progressive with the long wave patter through about the middle of, before amplifying toward the end of the period. The 0Z ECMWF trended a bit slower with the evolution of the smaller scale features for Tuesday into Tuesday evening. Early in the period, a surface cold front will sag south from the Ohio Valley to the Tennessee Valley and slow down or even stall for a time late Monday night into Tuesday evening as a couple of surface waves of low pressure move along it. This, in response to a couple of passing mid level shortwaves and at times some upper level dynamics, is expected to lead to unsettled weather across East Kentucky from the start of the long term period into Tuesday night. We have maintained some slight chances for thunder Monday night, and again for Tuesday into Tuesday afternoon, with at least marginal to weak instability in place. More southern locations appear to be a bit more favored for thunder chances and more precipitation. Drier weather will return on Wednesday and looks to last through Friday as ridging should generally dominate the weather through this period initially at the surface and then upper ridging building north and northeast from the Gulf of Mexico and working across the southeastern Conus. At the same time, a trough should move across the Intermountain West and Rockies and moves into the Plains nearing the Mississippi Valley at the end of the period. Ridging should generally dominate the weather through this period. However, the boundary should return north as a warm front and possibly bring a few showers by late Thursday into Thursday night while surface low pressure begins to organize over the Plains and tracks into the Great Lakes in response to the mid and upper level trough moving across the Rockies and Plains. This should put the region in the warm sector for Friday and Saturday. Both the trough axis and surface system should approach the area on Saturday, with precipitation chances increasing once again. There are model timing differences with the axis of the upper level ridge moving across the Temperatures will start out above normal, before trending colder behind the front at midweek. Another freeze continues to remain possible on Thursday morning although the pressure gradient and resulting mixiness and anticipated dry airmass may lead to less frost formation compared to what is expected tonight. Temperatures should moderate to above normal once again to end the week. && .AVIATION...
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(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 700 AM EDT SUN MAR 19 2017 Mostly VFR conditions were in place early this morning across eastern Kentucky. The exceptions with the airports were JKL and SJS, where MVFR CIGS were occurring. These two airports should transition to VFR by 15Z this morning. The rest of the TAF sites were VFR. BKN to OVC CIGs due to low and mid level cloud were in place at LOZ, SME, and SYM at TAF issuance. LOZ and SME should transition to VFR by 14 and 13Z respectively, with BKN low clouds at 3 to 4K expected by then. The clouds will slowly erode away as the day goes, with scattered clouds expected area wide by 16 to 17Z this afternoon. Winds during the period should be light and will shift from the north or northwest to the east and south this and tonight.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...AR LONG TERM...PG/JP AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.