Area Forecast Discussion
Issued by NWS Jackson, KY

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717 FXUS63 KJKL 162037 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 437 PM EDT Fri Mar 16 2018 .SHORT TERM...
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(This evening through Saturday night) Issued at 302 PM EDT FRI MAR 16 2018 Low pressure at the surface and aloft was over north central Kansas early this afternoon. At the surface a frontal boundary extended east from the low across central Tennessee. The focus of this forecast will be on this system as the upper low opens up and moves east across the OH valley on Saturday and the surface low moves east southeast across Kentucky. In response to the approaching low the front over TN will lift north as a warm front tonight before stalling again Saturday. Showers will develop across our area late tonight. Instability will be limited tonight but a strong low level jet may support some elevated convection late tonight as the warm front lifts north. As such we will include a slight chance of thunder over the southwest part of the area after 09Z. As the front lifts north Saturday there will be a break in the rain chances in the southern part of the area. Breaks in the clouds will develop across the the south on Saturday, and surface heating will lead to increased instability across the south Saturday afternoon. A significant temperature gradient is forecast across the area as warm advection and a little sunshine result in temperatures climbing into the upper 60s and lower 70s in the far south while temperatures remain in the lower to middle 40s over the far northern part of the area Saturday afternoon. With the approach of the upper level short wave trough and the surface cold front Saturday afternoon, thunderstorms may develop, especially where instability is greatest in the south and southeast. With decent shear a couple of storms could be strong or even severe. SPC has placed our area in a marginal risk for severe storms Saturday, with hail and strong gusty winds both possible. As the surface low exits off to our southeast Saturday night rain chances will diminish from northwest to southeast. .LONG TERM...(Sunday through Friday) Issued at 437 PM EDT FRI MAR 16 2018 The main feature to affect the region during the period will be a large low pressure system tracking from the high plains on Sunday, eastward across the Ohio/Tennessee valley region Monday night into Tuesday, and up the east coast later in the week. Initially, a frontal boundary will be well to our south, and surface high pressure passing just to our north will bring dry weather Sunday and Sunday night. As the low heads east, it will draw the front northward as a warm front, along with gulf moisture. Showers are expected to develop in response to this on Sunday into Sunday night. The exact track of the low and resultant northward limit of the warm front are uncertain, and will be the main determining factor for our temperatures Monday night and especially Tuesday. The current forecast is a middle ground of a wide range of possibility. Model forecasts of instability are being picked up by MOS, and thunder has been mentioned in the forecast for Monday afternoon into Monday night. Along with the coastal development, a significant eastern CONUS upper trough is forecast to develop, along with a large area of light precipitation in the cold cyclonic flow on the back side of the surface low. The GFS and ECMWF are not in perfect agreement, but both show this affecting our area at midweek. Unusually cold air is expected, and the rain should mix with or change to snow. Some light accumulation is a possibility late Tuesday night and Wednesday, but will be highly dependent on temperatures. At this point, the best shot at getting snow cover will be over the higher elevations in southeast KY, but temperatures a little bit colder than forecast (which is possible) would bring down the elevation for accumulations. The system pulls out and leaves fair weather for Thursday into Friday. Cold air advection eases and increasingly strong March sunshine will work on warming up the air mass.
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&& .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 144 PM EDT FRI MAR 16 2018 VFR conditions will prevail into the overnight period, but conditions will deteriorate late tonight and into Saturday morning as a warm front lifts north out of Tennessee and into Kentucky. The front will lift north in response to a low pressure system that will be moving east from the central plains. Clouds will thicken and lower overnight, with MVFR ceilings becoming widespread across the area by Saturday morning. Some IFR ceilings can also be expected, especially across the northern half of the forecast area. Showers will also occur late tonight and into Saturday morning. At this time the threat for thunderstorms late tonight into Saturday morning looks minimal. As a low level jet moves into the area early Saturday morning LLWS is expected to develop for a few hours. Ceilings should lift in the southern and central part of the area Saturday afternoon, but with heating from some sunshine a few thunderstorms will be possible Saturday afternoon. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SBH LONG TERM...HAL AVIATION...SBH is the U.S. government's official web portal to all federal, state and local government web resources and services.