Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 030856 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 356 AM EST Sat Dec 3 2016 .SHORT TERM...
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(Today through Sunday) Issued at 356 AM EST SAT DEC 3 2016 Surface high pressure will continue to overspread the state throughout the day today, passing just to our east by 6Z tonight. Overall this will result in light winds at the surface with llvl stratus clouds continuing to pull into the region from the NE through at least mid day in many locations. Llvl winds will begin to lighten and become more variable as the center of the high passes to our north and then heads east, allowing the llvl clouds to begin breaking up throughout the afternoon. Meanwhile, aloft, a shortwave will begin digging across the northern plains throughout the day, shifting eastward. This shortwave is expected to reach the Mississippi River Valley by Sunday, then move across the Ohio River Valley and points to the north by 0Z Monday. The upper level wind pattern will feature a jet streak across the Ohio River Valley ahead of the shortwave, increasing in strength as the shortwave nears. Mid/upper level winds will be westerly across KY and then SW just to our east. This will effectively pull moisture from the Gulf of Mexico northward and then eastward into the state. As such, this will result in high clouds expected to push northward into the CWA by later this afternoon. Moisture and clouds will continue to build this evening with the nearing mid/upper level wave, however it will have a hard time overcoming the bubble of dry air at the surface with the surface high pressure center still in place just to our east. Latest forecast soundings show moisture finally overcoming the drier air between 6 and 9Z at KSME and KLOZ in our southern CWA, between 6 and 12Z in the mid sections, and a few hours later in the northern CWA. Despite W to SW flow aloft, temperatures in the mid and upper levels will still be on the cooler side as precip moves into the region overnight Saturday, below freezing through much of the column. As such, even as temperatures at the surface may be at or above freezing at precip onset, rain may still mix with snow for the first couple of hours. However, temperatures will quickly warm as we head into the daytime hours, with the surface high continuing eastward and allowing warmer return flow at the surface. All precip will change over to rain during this time, with generally no snow accumulation or impacts expected. Rain is expected to continue through the day Sunday as the mid/upper level shortwave closes in on the region. This will produce generally between 0.10 and 0.20 inches or rain across the CWA, an overall light system but much needed none the less. .LONG TERM...(Sunday through Friday) Issued at 309 PM EST FRI DEC 2 2016 Active weather is store during the extended period, as a series of weather systems are poised to bring multiple rounds of precipitation to eastern Kentucky. The first round of precip is expected Sunday and Sunday night, as two phased areas of low pressure aloft move across the region. One system is expected to move across the northern CONUS, while a second area of low pressure is still forecast to traverse the Gulf Coast. The area between these two weather systems is where our precipitation will come from to end the weekend and kick off the upcoming work week. Some locations north of the Hal Rogers Parkway may see a few snow flakes mixing with the rain early Sunday morning, but the latest model data is suggesting that most precipitation will be in the form of rain Sunday. The best chance for precipitation looks to be Sunday afternoon and evening, as the southern stream system moves by to our south, bringing Gulf of Mexico moisture into the area. This initial round of precipitation should be coming to and end early Monday morning, as the causative weather systems move off to our east. After a brief respite, a second more potent area of low pressure is expected to move toward the area out of the southern Plains Monday afternoon and night. This system will be more intense and have more moisture with it than the first one. In fact, widespread soaking rainfall is expected across all of eastern Kentucky Monday night and Tuesday. Energy and moisture from this system will allow for isolated to scattered rain showers to linger across the area through Wednesday afternoon. There will be another lull in the weather Wednesday afternoon and evening, as a weak ridge of high pressure briefly settles over the region. A third and final weather system is then expected to move quickly out of the northern Plains and across the Great Lakes and Ohio River Valley regions Wednesday night through Thursday night. Based on the latest model temperature profiles, it appears that this mid to late week system will have a bit more warm air with it, so the precipitation forecast will feature less snow and much smaller snow accumulations for Wednesday night and early Thursday then previously forecast. There should be periods of rain/snow mix and snow late Wednesday night into Thursday morning. Most of the day on Thursday should feature all rain, as warmer air filters into the area. Another push of cold air may bring another round of rain snow mix and some isolated light snow showers to eastern Kentucky late Thursday night into Friday, as the upper level low departs to our east. Little if any snow accumulation is expected. Temperatures through the period will vary from below normal to above normal depending on the day. Sunday and Thursday should see highs in the 40s across the area, while Tuesday and Wednesday will most likely see highs in the 50s. The coldest day of the week could be Friday, when the mercury may only climb into the 30s area wide. Nightly lows will generally be in the 30s and 40s.
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&& .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 107 AM EST SAT DEC 3 2016 Models continue to struggle with the llvl stratocu deck moving across the region, bordering the line between MVFR/VFR, as high clouds also override across our SW, including KSME and KLOZ. Latest trends will support these generally MVFR llvl clouds continuing to take over all TAF sites through the overnight. A BKN (or at times SCT) MVFR deck will likely persist through much of the day tomorrow as well. A mid/upper level disturbance will begin to approach the region tomorrow afternoon/evening, starting in the south. Meanwhile high pressure will be in control at the surface. So as llvl clouds begin to clear out (as early as 16Z for KSME and KLOZ), high clouds will begin thickening to OVC. This occurrence will happen a little later, closer to 22Z at KSYM. Expect high clouds to continue to build down throughout the remainder of the night, but should stay within the high cloud vicinity through the TAF period. Overall winds will remain generally light and variable near the surface through the period, with stronger WNW to W flow aloft. However, the directional change and increase in flow will be gradual enough to not cause any wind shear problems throughout the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...AR AVIATION...JMW

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