Area Forecast Discussion
Issued by NWS Jackson, KY

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812 FXUS63 KJKL 211233 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 833 AM EDT Fri Jul 21 2017 .UPDATE... Issued at 832 AM EDT FRI JUL 21 2017 MCS dropping into KY from the Cincinnati area should affect our northern counties late this morning. POPs have been raised to likely category for this. It is unclear how well it will hold together. Movement has been extrapolated to the southeast, with a fading of the high POP with time. If it does not weaken, higher POPs will need to be extended further southeast. && .SHORT TERM...(Today through Saturday) Issued at 500 AM EDT FRI JUL 21 2017 The main concerns during the period are the levels of heat and humidity, and the extent of convective precip. A slow moving cold front was dropping south through Indiana and Ohio early this morning. An MCS was over northwest Indiana, with isolated showers stretching east into West Virginia. The coverage of precip through 06z was less than forecast by the models, which calls into question how well models will perform. The cold front is expected to make it to near the Ohio River this evening, before stalling and heading to the northeast as a warm front tonight and Saturday. The highest probability of precip will be in our northern counties closest to the front, with some POP enhancement also in our southeast counties due to terrain. Will hold all POP values to slight chance and chance categories. Max temps will be influenced by the extent of clouds and precip, and have some uncertainty. At this point, it appears that the temperature and dew point combinations will lead to heat indices generally shy of the advisory criterion, and will hold off on use of a NPW. .LONG TERM...(Saturday night through Thursday) Issued at 403 AM EDT FRI JUL 21 2017 Based on the latest model data, the extended will be active and will feature periods of showers and storms and cooler weather. It appears that a frontal boundary will meander about the lower Ohio Valley and Upper Tennessee valley during the extended. There should be rain chances each day, except Wednesday, as the front meanders about the area. The front may move far enough south on Wednesday, to keep precipitation out of eastern Kentucky. A second weather system moving from the south may bring showers and storms back to the area from Thursday onward, after only a brief respite. The best chances for showers and storms will be the afternoon and evening hours, with little if any thunder expected during the night time periods. Temperatures during the period should be around normal, or even slightly below normal at times, due to persistent cloud cover and repeated episodes of showers and storms. Daily highs are expected to average in the low to mid 80s most days for most locations. Nightly lows will start out in the lower 70s, but should generally be in the 60s for most of of the period. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 832 AM EDT FRI JUL 21 2017 Morning fog is thinning out, and VFR conditions are expected shortly after the period begins. However, an area of thunderstorms entering northern KY at the start of the period will probably affect the far northern and northeastern portions of the forecast area late this morning. It is unclear how long the storms will hold together and what the southern extent will be. VCTS was used late this morning at KSYM, but TAF amendments may be needed for late this morning to cover the convective system if it does not weaken. Once the morning thunderstorms are gone, there will still be a potential for more development later in the day, but there is not enough confidence to include it in the TAFS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...HAL LONG TERM...AR AVIATION...HAL is the U.S. government's official web portal to all federal, state and local government web resources and services.