Area Forecast Discussion
Issued by NWS Jackson, KY

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597 FXUS63 KJKL 210800 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 400 AM EDT Sat Apr 21 2018 .SHORT TERM...(Today through Sunday) Issued at 400 AM EDT SAT APR 21 2018 High pressure continues to assert itself across eastern Kentucky with only a few strands of cirrus streaming in. These will increase through the day downstream of an upper level low pressure system currently churning overtop Denver. Shortwave ridging will nudge eastward across the Commonwealth as it flattens, but heights/thicknesses will nonetheless increase as subsidence keeps dry conditions in place and leads to further warming this afternoon with highs topping out in the mid-upper 60s north of Mountain Parkway and low-mid 70s south. Light north/northeast winds will veer a bit more easterly tonight in response to surface ridging across the Great Lakes to mid-Atlantic coast crawling eastward. While cloud cover will gradually thicken/lower tonight, valleys in the Big Sandy region should still see a sizable dropoff in temperatures, cooling to the mid 30s. A few areas of frost will thus be possible once again along with some patchy valley fog. The previously mentioned upper low will dig south across the southern Plains and into the lower Mississippi Valley Sunday with an attendant surface low immediately downwind. Increasing precipitable water values and at least mid clouds will stream northeast into the Lake Cumberland region. Still some uncertainty as to how much the upper low will dig and subsequently how fast it will shift east, keeping the best rain chances southwest of Kentucky through the day. Downslope winds will aid in maintaining a dry near-surface layer, but will still keep low-end PoPs in for the Lake Cumberland region and far southeast Kentucky. Any rain that does occur through the afternoon will be light at less than one tenth of an inch, prior to better chances taking shape into early week. .LONG TERM...(Sunday through Friday) Issued at 336 PM EDT FRI APR 20 2018 A upper level ridge axis will still be extending across the Ohio and Tennessee Valleys Sunday. This will help slow the progression of rain showers activity northward and still may be too quick on the progression northward overall. Did opt to adjust from what the blended data provided for Sunday, but tried to remain match up with the neighboring offices. The NAM is the wetter outlier this afternoon for Sunday into Sunday night and this could be some influence in the blended data. This southern stream upper level low will remain the culprit for unsettled weather across the Ohio and Tennessee Valleys through much of the period. This southern stream system will eventually phase with a northern stream upper level wave, but the guidance diverges greatly at this point on the depth and forward progression of the northern stream feature. This leads to a low confidence forecast from midweek onward. The slight to chance POPs provided by the blended guidance seems reasonable at this point and therefore little changes were made to the forecast for this period. In general, the temperatures through the long term will remain near normal for this time of year. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 133 AM EDT SAT APR 21 2018 VFR conditions to continue with generally northeast to southeast winds of less than 10 knots. && .JKL WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 9 AM EDT this morning for KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ SHORT TERM...GUSEMAN LONG TERM...DJ AVIATION...GUSEMAN is the U.S. government's official web portal to all federal, state and local government web resources and services.