Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 190600 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 100 AM EST Mon Feb 19 2018 .UPDATE...
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Issued at 1245 AM EST MON FEB 19 2018 Did a quick update to adjust the near term PoPs as some bonus showers have formed ahead of schedule over the western parts of the area and are moving/developing deeper into the CWA. The updated grids have been sent to the NDFD and web servers. UPDATE Issued at 1114 PM EST SUN FEB 18 2018 Temperatures have reached their lows at most locations, as clouds have thickened up, and even a few showers are starting to develop across the southern portions of the area. Have fine-tuned the temperatures and POPs through Monday morning, with chances ramping up quite a bit over the next few hours, and cooler valley locations gradually mixing out. Shower chances will then gradually shift to the north through Monday morning as the warm front exits north of the Ohio River. Updates will be out shortly. UPDATE Issued at 707 PM EST SUN FEB 18 2018 Clouds are on the increase tonight out ahead of the approaching warm front, with scattered light showers already moving across southern Tennessee. It will take a little while to moisten up, so will leave the POP timing as is, with the better increase occurring after midnight. Eastern valleys are decoupling as scheduled, and will only make a few adjustments to the hourly temperatures and dew points over the next few hours to account for the trends in observations.
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&& .SHORT TERM...(This evening through Monday night) Issued at 400 PM EST SUN FEB 18 2018 At mid and upper levels, a ridge was centered south and southeast of Bermuda with a trough over much of the western to central Conus. A series of shortwaves were moving from the Rockies into the Plains while a closed low was moving through the Northwest Conus. An area of low pressure was moving across the upper MS Valley with a stronger sfc low over eastern CO/western KY. Meanwhile over the east, high pressure was centered to the east and northeast of the area while a warm front extended through the Gulf Coast states and then west and northwest into the Plains. Some mainly high clouds are working across the region with thicker high clouds and some low and mid clouds over the MS Valley. Surface high pressure will depart to the north and east with mid level heights expected to rise along the eastern seaboard tonight and into Monday. The initial surface low now over southwest MN should track into WI and Lake Superior and then on into Ontario and weaken while a surface low now over CO and KS tracks across the Central Plains and into the MS Valley as a couple of shortwaves move through the southwest flow between ridging off the southeast coast and troughing over the west. A warm front should develop over or move into the area tonight and lift north of the area on Monday. Southerly flow should transport deeper moisture into the region with isentropic lift. PW initially in the quarter to one half of an inch range should reach in excess of one inch by dawn. Behind the boundary on Monday, the region will get into the warm sector with shower chances diminishing. Further west, an upper low/shortwave should track south over the western Conus tonight and then begin to move east across the Intermountain west and into the Monday to Monday night period. The southwest to south southwest flow aloft should keep the baroclinic zone well to the west and northwest of the area through the end of the period. Meanwhile, the mid and upper ridge should build back into the southeast with rising heights and surface high pressure increasing across the southeast. As for temperatures, there should be a window of opportunity for eastern valleys to decouple this evening and make a run at the upper 30s, before clouds thicken and lower around or just after midnight. Showers should also move into the area or develop shortly after as moisture increases, especially aloft rather dramatically and insentropic lift increases as southwest low level jet increases. This should be a low qpf event with most locations measuring. The increase in winds aloft may also lead to increased winds above 2000 or 2500 feet with gusts on the order of 30 to 35 mph possible overnight into early on Monday. Well above normal temperatures are expected on Monday and Monday night. Record highs on Monday may be broken at JKL and LOZ as temperatures should reach the lower to perhaps mid 70s in many locations. A small ridge/valley split could occur on Monday night if clouds were to thin for a while. However, lows will be very mild for February likely not falling below 50 in all locations. .LONG TERM...(Tuesday through Sunday) Issued at 245 PM EST SUN FEB 18 2018 An anomalous ridge will remain anchored over the eastern US at the start of the period. Downsloping southerly flow, combined with 3 to 4 standard deviations above normal height anomalies will allow for a very warm day on Tuesday. Afternoon highs will be nearly 30 degrees above normal with readings topping out around 80 degrees. This will clearly be good enough for daily records, and will threaten our all time February high temperature records. While we are enjoying the warmth on Tuesday, a baroclinic zone will set up over the western Ohio river valley, focusing very heavy rain across that region. This boundary will eventually be pivoted eastward as a shortwave pushes northeast across the area on Wednesday. Models continue to slow down the precipitation chances, but still looks like a decent chance activity could reach us by late Wednesday. If nothing else, a little weakness in the heights could allow a few showers or storms to pop up on Wednesday, especially in our western zones. For the first time in quite a long time, LI`s are actually below zero Wednesday afternoon, so a few storms certainly are possible if enough instability can develop. The main axis of precipitation will shift into our area Wednesday night with the highest rain chances occurring at this time. Uncertainty increases greatly as we go into Thursday and beyond as it looks like we may have a few more rounds of rain targeting the Ohio river valley late in the week into the following weekend. At this point, looks like the best rain chances may come Friday and Saturday. Models show the baroclinic zone finally exiting as a cold front late next weekend allowing drier conditions to finally return late in the weekend or early into the following week. Given the tremendous uncertainty with rainfall amounts and timing, opted to hold off on any ESF or mention in the HWO at this time with regards to heavy rain. With 3 to 4 days of dry weather expected going into the next chances of rain, that may be enough time to allow rivers to recede and ground to dry out a tad. && .AVIATION...
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(For the 06Z TAFS through 06Z Monday night) ISSUED AT 100 AM EST MON FEB 19 2018 An approaching warm front will bring a period of showers and MVFR ceilings to most of the area into early Monday morning. Will lower all ceilings by 09z, where they are not already starting off as MVFR - along with the presence of passing rain showers - VCSH. Ceilings will raise back up to VFR levels by mid to late Monday morning, as the boundary lifts north of the area. An increasing low level jet, associated with the developing warm front will bring low level wind shear through at least the mid-morning hours on Monday. At the surface, light and variable winds will veer to the south at around 5 to 10 kts overnight, before increasing to around 10 kts, with gusts of 15 to 20 kts by mid to late Monday morning. Wind shear will also be a concern Monday night even as cigs will hold in the VFR category.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...KAS AVIATION...GREIF is the U.S. government's official web portal to all federal, state and local government web resources and services.