Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 151930 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 230 PM EST Sun Jan 15 2017 .UPDATE... Issued at 120 PM EST SUN JAN 15 2017 Upstream radar trends continue to point to an increase in drizzle or shower activity as the afternoon progresses. This is also in line with many of the short term model runs. Some of the recent HRRR runs generally support that idea, but differ from run to run in coverage and QPF. The ongoing forecast that brings likely pops into the northern two thirds of the area later this afternoon and into the evening still seems reasonable and was not changed at this time. Some area of fog persist across the northern half or so of the area, with some of this dense at the higher ridge observing sites such as JKL and PBX. Webcams indicate similar conditions to that near Wolfe/Powell Co line along the Mtn Parkway. Some fine tuning of the ridgetop fog will be done based on the 1 PM obs. Otherwise, hourly temperature and dewpoint grids were freshened up based on recent observations. UPDATE Issued at 1025 AM EST SUN JAN 15 2017 Radar and some observations such as recent KSYM observations are indicating some light drizzle occurring across generally northern portions of the area. Fog dense on some ridges lingers. Meanwhile, an area of showers over Indiana and western KY are slowing approaching the area ahead of a shortwave moving into the Lower OH Valley. The hourly grids have been updated to include a slight chance or isolated drizzle across the northern locations and highest terrain near the VA border through early to mid afternoon along with some fog on the ridges. Meanwhile, the area of showers should move into the area, especially northern and central sections with scattered to numerous coverage by mid to late afternoon per recent NAM, GFS, and short term model runs such as HRRR. UPDATE Issued at 625 AM EST SUN JAN 15 2017 WSR-88D radar showing the earlier relatively higher returns have waned, but we are still seeing some drizzle is spots. Otherwise biggest issue will be the patchy dense fog in spots this hour. Updated grids to reflect latest obs and trends but otherwise forecast is on track. && .SHORT TERM...
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(Today through Monday) Issued at 332 AM EST SUN JAN 15 2017 Surface analysis shows area of high pressure centered to the NW this AM across IA/IL region and quasi stationary boundary is now across portions of the TN Valley. Based on the upper level data, would suspect the 925mb boundary still resides across the region and 850mb just to our north. That said, WSR-88D radar does indicate a line of shower/drizzle has developed across the center of the CWA and is near where the SPC mesoanalysis shows weak forcing at the 925mb level as mentioned above. This will progress south through the morning and kept as a drizzle mention given some areas are seeing light drizzle outside this line. Overall the HRRR/CONSSHORT seemed to be handling this idea and therefore nudged my POPs in that direction. Based on the obs this morning would think fog is more of the patchy dense variety and therefore kept that going through early morning before tapering through mid morning. The previously mentioned surface high pressure will progress east today with winds veering around to the NE by this afternoon. The 850mb front will remain north as mentioned before, as a mid level wave/PVA rides along the baroclinic zone. These two forcing mechanisms combined with saturated column will lead to decent chance of rain showers late this afternoon into this evening mainly north of the Mountain Parkway. While this is a decent shot of rain showers, the QPE will remain light with only a couple of hundredths of an inch expected. POPs will wane through the evening from west to east as better forcing pushes east. Given the moisture in place did opt to add patchy fog in for a good portion of the region through Monday morning. For Monday did keep slight POPs in the north and far NE, but this may have to be looked at further. The only fly in the ointment here will be the aforementioned quasi stationary will likely lift back north, and therefore could lead to slight POPs ahead of the eastward progressing cold front. Better POPs for the cold front will take place beyond this forecast period. .LONG TERM...(Tuesday through Sunday) Issued at 230 PM EST SUN JAN 15 2017 Convoluted weather pattern throughout the long term period with split jet streams. Multiple closed lows will meander about the central part of the CONUS keeping southwest flow in place over our area and this will provide the one constant for the period: above normal temperatures. Relied heavily on the blended model guidance in this complex pattern. A cold front will be stretched out across the area Tuesday into Tuesday evening as a shortwave scoots across the Ohio Valley. This should provide for numerous showers during the day and cannot rule out a few thunderstorms with models showing some instability along with a fairly healthy 850 mb jet aloft. The chance for showers will linger into Wednesday morning as the front slowly works to our southeast. Timing is very suspect beyond Wednesday, but it appears now that we can expect a brief break Wednesday afternoon through Thursday morning. A southern stream disturbance then rides north-northeast out of Texas and this will bring renewed rain chances Thursday night into Friday. Saturday looks dry right now but another system ejecting out of the southwest appears to spread more rain across the area by Sunday.
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&& .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) ISSUED AT 130 PM EST SUN JAN 15 2017 Widespread IFR CIGS are currently being reported across the area with some stations such as JKL and SJS below airport minimums attm. A limited area near the TN and VA border including valley sites 1A6 and I35 are reporting MVFR. Some limited improvement but still IFR CIGS and or vis remaining is expected at all the TAF sites with some MVFR south of all sites through 0Z. However, a upper level wave will interact with the frontal zone lingering near the area to bring a renewed threat for rain showers and drizzle and this should maintain stratus build down across the area or result in these bases lowering by the overnight hours as the boundary begins to return back toward the area as a warm front. Thus IFR and possibly below airport min CIGS are again expected at the TAF sites during the 0Z to 15Z period. Improvement to MVFR may reach SME, LOZ, and JKL during the last 3 to 6 hours of the period. Light winds are expected through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...DJ LONG TERM...ABE AVIATION...JP

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