Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 211723 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 123 PM EDT THU JUL 21 2016 .UPDATE... Issued at 939 AM EDT THU JUL 21 2016 12z soundings and water vapor imagery indicate mid level dry air, which will be mixing down this afternoon. In the higher terrain KY mesonet shows dewpoints of 52 at Dorton and 59 at Black Mountain. With drier air mixing down this afternoon we will see dewpoints lowering and maximum afternoon temperatures higher than yesterday. This was already depicted in the current forecast. Have updated the NDFD based on latest observational trends, but this resulted in very little change to the previous forecast for this afternoon. UPDATE Issued at 635 AM EDT THU JUL 21 2016 Drier air will continue to mix down across the area today keeping skies mostly sunny and the weather dry. This will allow temps to surpass the 90 degree mark this afternoon. That being said, forecast remains on track so did a quick refresh to the hourly grids. Sent updated grids to NDFD and web servers. && .SHORT TERM...(Today through Friday) Issued at 352 AM EDT THU JUL 21 2016 High pressure will remain in control of our weather today. Drier mid level air, currently seen on GOES WV imagery, will work its way through most of our area, helping dew points mix down to near 60 degrees in spots. So even though temps are expected to surpass 90 degrees this afternoon, humidity will be low compared to recent days. Additionally, MCS activity to our northwest may throw some debris cloudiness overhead from time to time, especially in the southwest portion of the forecast area. The main upper level ridge will shift slightly more to our west tonight. This will allow the low level winds to turn towards the southwest on Friday, ushering in higher moisture. A wave in the upper level flow is progged to drop southeast around the ridge towards our area late Friday afternoon, bringing shower and thunderstorm chances back into the forecast. The best chance for shower and storm activity will likely be beyond the short term period, into Saturday morning and afternoon. Temperatures will reach into the lower 90s today and tomorrow. However, heat indices are expected to reach 100 degrees in spots on Friday afternoon due to the higher dewpoints. Additionally, debris clouds and any shower activity late Friday adds uncertainty to the temperature forecast. .LONG TERM...(Friday night through Wednesday) Issued at 352 AM EDT THU JUL 21 2016 A persistent upper level ridge over the central United States continues to be the focus for the first portion of the long term forecast. This ridge in conjunction with the development of surface high pressure over the southeastern United States will allow for decent moisture transport into the Ohio Valley, creating heat indices that will approach the 100 degree mark over portions of Eastern Kentucky. That being said, a few models have been hinting at some shortwave passages throughout the weekend that may help moderate temperatures and keep us below advisory criteria. It should be stated that the current regime presents its own challenges in regards to predictability, and given historical model performance in passing these shortwaves through the periphery of a strong ridge it was decided that PoPs should hang around the 30-40 range during peak heating over the weekend. Towards the start of the work week our next weather maker begins to take shape as a trough begins to deepen over the Great Lakes and amplify the largely zonal flow over the northern United States. As this low pressure system propagates east it will drive a cold front into the mid-Atlantic late Monday into Tuesday morning. Following frontal passage we should see a brief reprieve from the oppressive heat in days past, as we return to more reasonable summertime conditions. As the work week progresses, conditions should remain fairly calm save a few diurnally driven showers and thunderstorms. && .AVIATION...
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(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 121 PM EDT THU JUL 21 2016 VFR conditions will prevail through the forecast period. Drier air aloft continues to mix down to the surface and even in the southwest part of the forecast area dew points have fallen into the lower 60s. Low level moisture will begin to increase tonight, but current thinking is that fog will be limited to locations in some of the river valleys. With this thinking in mind will not include any fog in the TAFs tonight. Winds will remain light and variable.
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&& .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...SBH SHORT TERM...JVM LONG TERM...GEOGERIAN/GOUDEAU AVIATION...SBH

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