Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 170614 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 214 AM EDT Sat Mar 17 2018 .UPDATE... Issued at 1022 PM EDT FRI MAR 16 2018 Made a few adjustments to both hourly temperatures for the rest of tonight and tonights minimum temperatures. These were based on trends in the latest obs from around the area. Decided to decrease temps by a degree or so across the board. Also removed any remaining outdated evening wording from the zone forecast text product. The rest of the forecast was in good shape with no other changes needed. UPDATE Issued at 741 PM EDT FRI MAR 16 2018 The forecast is on track so far this evening. Still expecting widespread cloud cover, rain showers, and perhaps even a few storms to spread across the area late tonight. Ingested the latest obs into the forecast grids to establish new trends. Otherwise, no forecast update is planned at this time. && .SHORT TERM...(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. && .AVIATION...
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(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 214 AM EDT SAT MAR 17 2018 A warm front is currently moving northward into eastern Kentucky and will continue to shift north through the state throughout the overnight hours. This warm front will then quickly be followed by a passing low pressure system across the southern portion of the state during the day today, exiting SE of the state by this evening. In response to these systems, abundant moisture flow into the region will result in thickening and lowering clouds for the period as well as precip impacts, including the chance for thunder at all TAF sites (with possibly the exception of SYM which will remain north of the warm front). CIGS will lower to MVFR from west to east between 9 and 13Z, with rain showers and isolated T expected to move in during this time as well. CIGS will continue to deteriorate to IFR at KSYM, KJKL, and KSJS by around noon even as rain chances cease briefly for the early afternoon. -SHRA and VCTS will then return for the late afternoon and evening with continued IFR to MVFR CIGS. Thunder potential will cut off by around 0Z, and rain chances will start to diminish from west to east throughout the rest of the TAF period as the low pressure system exits to the SE. However, low CIGS are expected to persist. Winds will generally be light and variable under 10 knots throughout the period. Some wind shear will be possible at KSME, KLOZ, and KJKL during the morning hours.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...SBH LONG TERM...HAL AVIATION...JMW is the U.S. government's official web portal to all federal, state and local government web resources and services.