Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 171916 AAC AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 216 PM EST Sat Feb 17 2018 .UPDATE... Issued at 208 PM EST SAT FEB 17 2018 Hourly grids have been updated based on KFGX observation and social media reports to lower temperatures in mainly far northern Fleming County to near or just above freezing. Some mixed precipitation has been falling further south to locations north of I 64. Generally a dusting to one half of an inch should fall in most of this area. With a half of an inch to one inch possible in northern Fleming County. The snow could come down hard enough, mainly in northern Fleming County for a bit of slush on the roadways at times. With accumulations expected to remain at no more than an inch due to temperatures at or above freezing, and locations nearing an inch expected to only be a fraction of far northern Fleming County, an SPS was issued for the next couple of hours for the far northwest counties. The heavier rainfall closer to the TN border continues to remain the main concern with rain rates having picked up over the past couple of hours. Some locations are nearing an inch of rain if not having exceeded an inch of rain already. Flooding of low lying areas near the TN and VA borders is anticipated with rises on area rivers. UPDATE Issued at 1205 AM EST SAT FEB 17 2018 Rain continues to overspread the region late this morning with KFGX observation pointing toward the possibility of mixed rain and snow or even just plain snow and above freezing temperatures in far northern Fleming County. Any snow or mixed rain and snow in the far north should change to just plain rain in the next 1 to 2 hours. Rainfall rates so far have not been that intense, although heavier rainfall rates recent in the 0.2 to 0.3 inch per hour rain over parts of middle TN are upstream. Most of the guidance points toward that activity to move into the Upper Cumberland portions of the near the TN border and then spread northeast along the VA border. The 6Z and 12Z model guidance, especially from the NAM and GFS have higher qpf near the VA and TN borders, especially in the Bell, Harlan, and Letcher county area. With this in mind, QPF has been increased a third to a half of an inch across the southernmost counties. The Flood Watch remains valid with no changes at this time. Radar trends and rainfall rates will continue to be monitored for any changes that might be needed. Instances of rock and mudslides as well as ponding of water on roadways are expected. Rises on creeks and streams may lead to low lying area flooding with rises on several points on the rivers expected. Confidence is greatest of downstream points reaching flood stage on the Cumberland and Kentucky basins, but this is all dependent on QPF. UPDATE Issued at 640 AM EST SAT FEB 17 2018 Isolated rain showers will be moving into the southwestern portion of the forecast area early this morning. The forecast is still on track with this for the most part, so major update is required at this time. The latest obs were ingested into the forecast grids to establish new trends. && .SHORT TERM...(Today through Sunday) Issued at 300 AM EST SAT FEB 17 2018 An area of low pressure will bring precipitation to eastern Kentucky today, as it makes it way across the Tennessee valley. There may be a slushy mix of rain and snow along the leading edge of the precipitation this morning, as it moves from south to north across eastern Kentucky. There may be some light slushy accumulations in isolated locations, but all in all the snow should have very few if any impacts. The snow should be gone by around noon today, as temperatures will have warmed well above freezing by then. The rain should taper off quickly this afternoon and evening, and should be gone by around dawn on Sunday. Another weather system may bring a second round of rain to the area by early Sunday evening. Temperatures are expected to remain slightly below normal today, with highs in the low to mid 40s on tap across the area. Tonight`s lows will likely be above normal, due to the influence of cloud cover and a brief period of southwest flow. A warm up is in store for Sunday, as winds shift around to the southeast and south, which could lead to some downslope warming during the day across eastern Kentucky. We should see highs on Sunday rise into the mid to upper 50s. .LONG TERM...(Sunday night through Friday) Issued at 410 AM EST SAT FEB 17 2018 The models are in good agreement with the broad scale pattern aloft through the extended portion of the forecast. They all depict a semi-static ridge through the southeast holding broad and deep southwest flow in place over the Tennessee and Ohio Valleys. This ridge will shift a bit through the seven day forecast but its influence will be dominant for the weather across Kentucky. Specifically, its burgeoning heights on Monday off the coast of Florida will support higher heights for Kentucky through Wednesday. The better energy lifts out of the area initially Sunday night with the rising heights and as a result, through Wednesday morning, the mid level energy stream remains too far north to have a big influence on the convection chances for our area. This changes later Wednesday with a better push of energy into the state associated with a weakening trough sliding through the Ohio Valley. After this point, the model variance increases with the ECMWF holding the southeast ridge onshore Florida compared to the weaker and more displaced to the southeast GFS. While the model agreement suffers at the end of the period it remains clear that eastern Kentucky will be in a wet and very warm pattern through the entire latter parts of the forecast. A general model blend looks reasonable for the extended. Sensible weather will feature a drying trend for Sunday night as a warm front lifts through and pulls away to the north. Mostly dry weather should commence through early Wednesday under ridging aloft and sfc high pressure off to the east. The pressure pattern will continue to support ample southwest winds bringing in warm and moist air from the south. This air mass will be activated on Wednesday as a sfc cold front approaches from the northwest with a potential for thunder. This boundary looks like it will stall out over the area and we could see another surge of moisture and lift develop for Kentucky into Thursday - prolonging the concerns for excessive rainfall well into the upcoming week. Another wave will then be possible for Friday extending this warm and wet period. Did make some changes to the lows each night of the long term portion of the forecast for terrain distinctions given a prolonged environment favorable for ridge to valley temp splits. As for PoPs, did beef them up for that latter wave from the ECMWF on Thursday that may not be as well represented in the model blend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 140 PM EST SAT FEB 17 2018 MVFR to IFR with rain showers are currently affecting the TAF sites with this persisting in most areas through around 21Z to 01Z. Some locations may fall to near or below airport mins at times. Although the rain will taper off by 3Z in all locations MVFR and IFR should prevail in most locations through 9Z, with improvements to VFR from northwest across the entire area thereafter. Winds should be generally light and variable. && .JKL WATCHES/WARNINGS/ADVISORIES... Flood Watch until 10 PM EST this evening for KYZ080-084>088-110- 113-115>120. && $$ UPDATE...JP SHORT TERM...AR LONG TERM...GREIF AVIATION...JP is the U.S. government's official web portal to all federal, state and local government web resources and services.