Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 151952 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 252 PM EST Fri Dec 15 2017 .SHORT TERM...
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(This evening through Saturday night) Issued at 252 PM EST FRI DEC 15 2017 Current conditions across the area features a lingering low level stratocumulus layer slowly pushing to the east. In fact, the western edge is now beginning to cross in the Somerset and Fleming County area. With drier air working in and westerly winds pushing the layer out, will begin to see clearing and lifting skies heading into tonight. In fact, the lingering cloud cover stunted the high temps for today leaving a rather cold night on tap with low temperatures dropping into the lower 20s. The clearing skies will continue into the day for tomorrow with stout southwest winds engaging during the day. This will bring warm air advection into eastern Kentucky with high temperatures during the day rebounding into the upper 40s to around 50. The slightly moist air will be slow to enter the area for Saturday leaving dew points in the mid 20s. Concerning Sunday night, models have significantly slow the approach of the system from the southwest and thus, the chance of the lower layer saturating in time for surface temps to be below freezing is very unlikely at this point. Warm air advection into the area will warm temperatures in time for an all rain event. Mid and upper level cloud cover quickly moving into the area will also lessen the ridge to valley differences in temperature. Thus, the short term forecast remains a temperature and cloud cover forecast. .LONG TERM...(Sunday through Friday) Issued at 230 PM EST FRI DEC 15 2017 Morning runs are in reasonable agreement with the mid/upper level pattern through the period. As usual more significant differences show up in the lower level details. The pattern remains amplified and generally progressive. However, southern stream energy is distinctively slower with an occasional pause in the movement of disturbances across the deep south. The end result is a type of split flow regime. Weather with this type of pattern is typically uneventful for those caught in the middle. But longer term solutions suggest the potential for some interesting weather, hinting that a mean split flow could persist but narrow a bit allowing both the northern and southern streams to become more interactive across our region before the end of December. At present there are three main features of interest. The first is a short wave trough passing through the mid Mississippi Valley and into the Great Lakes Sunday. This disturbance is weak and fills as it progresses northeast with time. The second is a similar type disturbance that fills as it pushes through the southern Plains and into the Tennessee Valley by Tuesday night. Of particular interest is the 12Z ECMWF, which has suddenly trended much slower with the second disturbance, bringing it through the region about 24 hours later than the GFS and Canadian. Thereafter not seeing any well defined systems or disturbances through our area until just beyond the end of the period as a deep northern stream trough approaches the Ohio Valley from the west. By Sunday we are well entrenched in the warm sector of the core track of storm systems and generally remain there through the end of the extended window. Sensible weather is best described as warmer than normal with the occasional chance of some rain. The first disturbance will bring a chance of rain to our entire area by late in the day Sunday as the system passes to our northwest. The second disturbance passing through the Tennessee Valley could provide another opportunity for some rain across the area. But confidence is low on timing with the most recent run of the European. At present will stay with the blends, which shows overrunning light rain developing mainly over the southern half of our forecast area Monday night into Tuesday, but more likely Tuesday. But keep in mind the ECMWF brings that precipitation into the area as late as Wednesday afternoon or night. The threat of precipitation returns once again by Friday as the aforementioned northern stream trough approaches from the west. On average our temperatures will run above normal, but especially with respect to daily highs running generally in the 50s, possibly approaching 60 by Monday. Sunday and Wednesday will be cooler, with highs in 40s on Sunday and around 50 Wednesday. Overnight lows will run a bit closer to normal each night, but appear to remain above freezing for many locations.
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&& .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 1231 PM EST FRI DEC 15 2017 Current conditions across eastern Kentucky feature a lingering low level stratocumulus deck that is slowly progressing east across the area. This deck will slowly lift and dissipate by the evening hours as southwest flow engages behind it. Timing this will be the key so will keep MVFR conditions through 22z to 00z at the TAF sites to time this. After this, skies will give away to a cirrus layer and clearing skies heading into tomorrow as high pressure passes through. Expect the winds to remain west and gusting to 20 knots at some place before becoming light and variable by 00z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SHALLENBERGER LONG TERM...RAY AVIATION...SHALLENBERGER

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