Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 200300 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1000 PM EST Thu Jan 19 2017 .UPDATE...
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Issued at 1000 PM EST THU JAN 19 2017 WSR-88D continues to show rain showers spreading slowly north and east this hour. Most of the amounts have been light across the CWA, but areas toward the Lake Cumberland region have pick up around a quarter of an inch. Rain showers will continue to spread east through the night and adjusted POPs with latest trends. Also adjusted for latest obs and trends. UPDATE Issued at 837 PM EST THU JAN 19 2017 WSR-88D radar showing best coverage of rain showers remains across the Lake Cumberland region this hour. It seems like some downslope flow is keeping precip more confined to those areas initially. Either way think the moisture will continue to spread east through the night leading to rain for most overnight. Did speed up the overall progression east, as some of the short term guidance was too slow including the HRRR. The models are also struggling with a induced 850mb jet that punches north through the night, and right now would think the short term guidance has best handle over the faster GFS solution. The previous assessment of the jet was based on 00Z soundings and current VAD wind profiles. Overall the jet alignment would bring better QPE to areas along and west of the I-75 corridor and more also over the Bluegrass. Also updated with latest obs and trends in terms of temps/dews/winds. UPDATE Issued at 540 PM EST THU JAN 19 2017 WSR-88D radar showing initial band of precip moving toward the Bluegrass and this is lining up close where the warm front is most likely located. The overall better upper level dynamics and rainfall will progress north and east through the night. The challenge this shift will be how much do we speed this up based on the latest surface/remote sensing trends versus the latest guidance trends. That said much of the guidance remains on the slow side at this point including the HRRR. Did opt to speed things up some this update based on the radar trends and will continue to assess this for the next update. Otherwise this update included freshening up the latest obs and overall trends for temps/dews/winds.
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&& .SHORT TERM...(This evening through Friday night) Issued at 415 PM EST THU JAN 19 2017 A small area of showers has moved into the southern part of the JKL forecast area this afternoon. This is teaser in front of a large area of rain/showers over central and western KY at mid afternoon. The precip was the result of an upper level wave coupled with warm air advection. Models agree on this precip moving through the region tonight. Downslope flow will cut into the precip in our eastern counties, but even there it should eventually rain. However, precip totals will be lighter in the east. Most of the precip will be exiting to the northeast with the warm front around dawn on Friday, with just some spotty very light showers possibly lingering into the day due to persistent low level moisture. A few peaks at the sun in the warm air mass will push readings into the 60s during the day. Mild, benign weather is in store Friday night. Cloud cover on Friday night is somewhat uncertain. MOS data and blended model data suggest quite a bit of cloud cover. However, forecast soundings look like the clouds could break. Have played it toward the MOS and blended data for the time being. .LONG TERM...(Saturday through Thursday) Issued at 355 PM EST THU JAN 19 2017 The extended forecast period begins on Saturday with a continued active and somewhat progressive pattern through the weekend and into next week. The first feature of the extended will eject northeast from the lower MS valley and into the southern Appalachians bringing light rainfall into eastern Kentucky. As the next feature continues to lift north through the area, some decent instability will advect into the area Saturday afternoon through Sunday afternoon. In fact, models and SPC show at least a slight chance for general thunder in the area. Will stay with collaboration with neighboring forecasters and SPC and keep thunder in the forecast through the weekend. In addition, the unseasonal airmass advecting into the area will allow for temperatures soaring into the upper 60s for highs across eastern Kentucky, possibly breaking a few records on Saturday and while not as quite as warm on Sunday, still a good 20 to 23 degrees above normal. Heading into Monday, another upper low dives into the lower MS valley before ejecting east and up along the lee side of the Appalachian Mountains bringing additional rain into eastern Kentucky. Expecting an additional half an inch with this rainfall to impact the far eastern Kentucky areas. As this feature exits, colder air filtering in behind may allow for rain to change to a mix of rain and snow on top of Black mountain on Monday night. After a break in the weather on Tuesday, another bout of southerly flow will allow high temps on Tuesday and Wednesday will climb near 60 degrees again before another bout of rainfall moves into the area late Wednesday afternoon through Wednesday night. As the front passes through late Wednesday night, this will begin an overall cooling trend through Wednesday night and beyond Day 7. In summary, much of the extended remains warm and wet with the consensus being around a couple inches of rain through eastern Kentucky but the GFS is quite a bit wetter than the Euro on the Sunday night into Monday system. The consensus is a bit less but something to keep in mind heading into next week. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 621 PM EST THU JAN 19 2017 First slug of rain along the warm front is advancing across the Bluegrass region this hour. Generally most will keep VFR CIGs, but isolated MVFR CIGs are possible. Otherwise all eyes turn to the better upper level dynamics and surface lifting that will progress north and east through the night. Did speed this up in this TAF update based on the latest trends and will look to do additional amendments as necessary through the night. That said, most of this will be more in the MVFR for CIGs/VIS, but again occasional IFR can`t be ruled out. For the most part we are looking at light winds for the period with winds out of the SE to begin and these winds will veer around to the SW to round out the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...HAL LONG TERM...HAL/SHALLENBERGER AVIATION...DJ is the U.S. government's official web portal to all federal, state and local government web resources and services.