Area Forecast Discussion
Issued by NWS Jackson, KY

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422 FXUS63 KJKL 180805 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 405 AM EDT Fri Aug 18 2017 .SHORT TERM...(Today through Saturday) Issued at 400 AM EDT FRI AUG 18 2017 07z sfc analysis shows a broad and fairly deep area of low pressure over the Great Lakes with a cold front stretching south and southwest through the Ohio Valley. This front is just west of the JKL CWA and pressing eastward with clusters of showers and embedded thunderstorms out ahead of it. A few of these clusters are exhibiting training and will have to be monitored for excessive rains through the next few hours. Clouds have overspread most of the CWA early this morning ahead of the boundary and with the convection, though some clear patches are found in the far east where the best shot at seeing some fleeting, but locally dense, fog exists. Temperatures are running in the very mild low 70s most places with dewpoints equally high. A few of the convective cells have also been able to bring down some higher wind gusts - up to 30 mph from the southwest, otherwise winds are generally light and from the south throughout eastern Kentucky early this morning. The models are in good agreement aloft building a trough over the region through the short term portion of the forecast. They all depict a decent short wave passing through the northern parts of the area this morning as height falls spread through Kentucky. The troughiness over the region will be reinforced on Saturday as a substantial wave moves across the Ohio Valley with further height falls as the main trough bottoms out. This features moves by quickly, though, with heights starting to rebound by evening. Given the good model agreement have favored a general blend with greatest consideration to the radar trends and higher resolution HRRR in the near term - NAM12 thereafter. Sensible weather will feature showers and potential thunderstorms passing through the CWA for the first part of the morning with much of this taking place in the pre-first period time frame - so will run the ZFP formatter with that in mind. Drier air and clearing skies then move into the region this afternoon with not so high dewpoints on tap. As the air mass changes today, a cooler but still mild, night will ensue but cold to neutral advection will limit terrain differences, though some valley fog can be anticipated under a regime of mostly clear skies and light winds. For Saturday, slightly more comfortable humidity levels will not prevent temperatures from climbing into the seasonable norms of mid 80s for highs under partly sunny skies. Given the trough push aloft, though, cannot rule out a stray shower or storm, mainly in the far north during the day, but limited moisture availability should make this a minor concern. Once again the CONSShort was used as the starting point for the grids through the short term portion of the forecast with only small adjustments to temperatures for terrain distinctions. As for PoPs, mainly adjusted them up this morning given the ongoing radar trends and beefy HRRR through dawn. Also trimmed them back quicker than guidance later this morning. .LONG TERM...(Saturday night through Thursday) Issued at 405 AM EDT FRI AUG 18 2017 This will be issued shortly. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) ISSUED AT 200 AM EDT FRI AUG 18 2017 Small clusters of showers and a few embedded thunderstorms are pushing deeper into the CWA and will start affecting the other TAF sites over the next couple of hours continuing through dawn - similar to what KSYM is seeing currently. Could have some IFR conditions, mainly from VIS during this time. After 10Z the showers and storms will taper off west to east into the hours just before and after sunup today. Some patchy fog will be possible at the TAF sites as the rain starts to clear up heading toward 12z but will leave that out for now and cover the visby limitations with the prevailing showers and VCTS during that timeframe. Winds, outside of any storm, will be light and variable through mid morning before picking up from the west at 5 to 10 kts post fropa. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...JMW AVIATION...GREIF

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