Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 170759 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 359 AM EDT Mon Jul 17 2017 .SHORT TERM...
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(Today through Tuesday) Issued at 355 AM EDT MON JUL 17 2017 A shortwave will be present across the central Appalachians and eastern KY during the next couple of days, as upper level ridging continues to expand eastward into western KY today and central KY Tuesday. At the surface, a weak stationary boundary will be present along the Ohio River and portions of northern KY, where it will remain through the short term portion of the forecast as it slowly continues to fizzle out. A ribbon/skinny area of high pressure will be be stretched across the state, just south of this stationary front. As such, showers and thunderstorms will be possible, mostly confined directly along the frontal boundary and to our SE in conjunction with the upper level shortwave. It is likely that we may see no convection during the day in our CWA, with the frontal boundary setting just far enough to our north and west, though can`t rule out a few stray showers/thunderstorms in our far northern counties during peak heating. Coverage will be super isolated at best, but did mention some slight chances in the far northern fringes of the CWA between 18 and 21Z. Elsewhere, only a few fair weather CU are expected throughout the afternoon. All convection and clouds will quickly dissipate overnight, leaving another clear and calm night across eastern KY conducive for potential fog development. Continued with patchy to areas of fog for the river and deeper valleys overnight tonight. For Tuesday, much of the same set up is expected. The only difference will be the slight strengthening of the shortwave located over the Central Appalachians. As afternoon convection develops, this slight uptick may be enough to expand coverage across the high terrain along the VA and KY border. Kept mention of slight chance pops here right along the border through the afternoon as a result. While the frontal boundary to our north will also still be present, it will be nearly fizzled out and moisture starved. Not expecting any convection to affect the CWA from this feature. Temperatures will be similar both days as the pattern remains very similar, reaching the upper 80s during the afternoon. A little bit better moisture return during the day Tuesday, so humidity values will be on the increase a bit compared to today. Overnight lows tonight will be mild, generally in the 60s with a good ridge valley split expected to set up once more. .LONG TERM...(Tuesday through Sunday) Issued at 359 AM EDT SUN JUL 16 2017 An upper low will remain anchored across the Nunavut territory and Northwestern Passages of Canada into Hudson Bay through the upcoming weekend, as an upper high dominates a majority of the southern and central United States. This will bring a hot and sultry airmass into eastern Kentucky for mid week through the weekend as mid level heights of 590+ dam remain in place. Any showers or thunderstorms will wind down quickly Tuesday evening along the Virginia line with the loss of daytime heating. Despite the eastern periphery of the approaching upper high sprawling into eastern Kentucky Wednesday, west/northwest low level winds may be enough to generate some upslope-induced storms along the Virginia border once again during peak heating as temperatures warm to near 90 degrees. A strengthening cap will put a damper on any storms for Thursday as the core of the high makes its closest approach while centered on the mid-Mississippi Valley. This will spell temperatures soaring into the low-mid 90s, which when combined with dewpoint temperatures in the mid 60s to near 70, will create some heat index readings of 100+ degrees. The one saving grace to an even warmer and muggier airmass will be the position of the axis of the high in all likelihood remaining west of eastern Kentucky, therefore keeping northwesterly flow in place aloft as opposed to a long duration of southwesterly flow out of the Gulf of Mexico. An upper impulse looks to swing far enough south into the Great Lakes/upper Ohio Valley by Friday to send a weak frontal boundary toward the Ohio River. While this feature should remain well north of the Bluegrass, the high aloft may become suppressed far enough south to allow for some convective initiation along southward propagating outflow boundaries to make it into northern to central Kentucky. Saturday looks to be a similar setup with high temperatures still generally holding in the low 90s with overnight lows only dropping into the low 70s. Will have to watch the evolution and whether or not cyclonic flow can dig far enough south by late weekend/early next week. If so, this would bring more bonafide rain chances to eastern Kentucky along with a reprieve from the stretch of heat.
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&& .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 142 AM EDT MON JUL 17 2017 Flight conditions will be VFR for most of the period. The only exception will be valley fog that will likely develop again tonight. The fog is not expected to be as pervasive as it was in our valleys yesterday morning, but it still may affect SME to some extent due to its proximity to a larger lake. Have left it out of the other TAF sites with a tempo for MVFR added at SME. No other forecast concerns through 6z Tuesday with just some fair weather cu during the day today and very light winds through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...GUSEMAN AVIATION...GREIF/JMW

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