Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 052000 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 300 PM EST Mon Dec 5 2016 .SHORT TERM...(This evening through Tuesday night) Issued at 300 PM EST MON DEC 5 2016 An are of low pressure aloft is forecast to move out of the southern Plains/western Gulf coast region this evening, and will be our primary weather maker through tomorrow night. Most of the latest model data is suggesting that precipitation onset will still be a couple of hours later than the night shift forecast was indicating. The new forecast will reflect a blend of the latest model data with precipitation onset anticipated around 1Z this evening in our far southern counties, or roughly two hours later than previously forecast. Based on the expected temperature profiles, precipitation will be in the form of all rain across eastern Kentucky. The best chance for rain will occur from late tonight through Tuesday afternoon. The rain should begin to taper off Tuesday afternoon and evening, with the last rain showers exiting the area between 9 and 10Z Wednesday. Area wide we can expect around an inch of rain from this event. Temperatures are expected to run at or slightly below normal through tonight, with a non diurnal temperature progression tonight. There will likely be a period of time tonight during which temperatures actually begin to increase, as winds also increase and shift more to the south and widespread precipitation sets in. Highs on Tuesday are expected to top out in the 50s, with lows in the 40s tonight and the 30s Tuesday night. .LONG TERM...(Tuesday night through Sunday) Issued at 510 AM EST MON DEC 5 2016 Models are finally showing better agreement with mid/upper level features through the extended and have even seen some trends towards better agreement in sensible weather elements. A broad trough moving through the Intermountain west at the start of the period will reach the Ohio Valley Wednesday night, passing through during the day Thursday. The 0Z GFS and Canadian, having been the more consistent runs, are a bit stronger with the mid level features of this system than the 0Z ECMWF. Regardless the boundary layer and sfc features associated with this disturbance are quite weak. Timing is similar with all solutions now, with the ECMWF only slightly slower. Overall trends are for lower pops and less QPF potentials. However, this system will still usher in some very cold air into the region, with H850 temperatures bottoming out close to -15C. The high pressure system building in behind this disturbance will settle down directly over the Commonwealth Friday night, allowing temperatures to drop into the low to mid teens by Saturday morning. Would not be surprised if morning lows flirted with some single digits Saturday in our typically colder valley spots. Thereafter return flow develops rather quickly, pulling plenty of moisture northward back through the MS valley and into the OH. If initial indications are correct, fairly strong isentropic lift will bring overspreading precipitation back into our area as early as Sunday. Too early to capture details at this time, but with the cold air in place imagine that precipitation will probably fall as a wintry mixture at the onset early Sunday morning before transitioning to just rain through the day. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) ISSUED AT 1238 PM EST MON DEC 5 2016 Widespread cloud cover will persist across eastern Kentucky through the end of the TAF period. These clouds are associated with both a departed area of low pressure aloft and a second upper level system that will approach from the southwest this evening and tonight. MVFR CIGS are expected through between 5 and 7Z tonight. After that, much lower clouds are forecast to move in, with IFR TO LIFR CIGS of around 500 feet expected. The first rain showers should begin moving across the TN border into eastern KY between 1 and 2Z this evening, with the rain becoming widespread by between 6 and 8Z area wide. SME and LOZ can expect rain to affect their sites around 5Z, JKL by 6Z and SYM and SJS between 8 and 9Z. IFR to MVFR VSBYs will be possible with any rain showers, with the lower VSBY associated with the more intense rain showers we will experience late tonight.These low CIGS are expected to persist through the end of the TAF period once they set in. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AR LONG TERM...RAY AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.