Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 240900 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 400 AM EST Sat Feb 24 2018 .SHORT TERM...(Today through Sunday) Issued at 400 AM EST SAT FEB 24 2018 The latest surface map features a stationary boundary aligned southwest from eastern Kentucky down into the Arklatex region. Aloft, troughing remains poised across the Rockies, with deep southwest flow streaming in across the Mississippi Valley, and ridging still hanging in across the western Atlantic. Showers have been increasing in coverage overnight, thanks to a low level jet moving into the Tennessee valley. Widespread showers can be expected through Saturday morning, as the jet continues to advect northeast into our area. Some of the showers will be moderate to heavy, with generally around a half inch of rainfall for most locations between what falls through dawn and the rest of the morning. There may be even a few embedded thunderstorms, with some locally higher amounts of rainfall. The stationary boundary will lift back to our north as a warm front by late this afternoon, allowing for a lull in convection, especially across our southeast. Some thinning of the clouds is also expected, so have gone a little warmer on the highs, with mid 70s likely. Temperatures elsewhere will range from the mid 60s north of I-64, to the lower 70s south. The relative lull in the convection will last into this evening, before a stronger cold front moves in well after midnight. Some stronger wind gusts will be possible with any storms that hang on, but instability continues to look weak, and the best forcing looks to remain just off to our west and northwest. Locally heavy rainfall will be possible, but given the progressive nature of the front, any hydro problems should be more isolated for most locations. Showers will exiting on Sunday in the morning as the front exits off to the east, with a noticeably drier air mass working in during the afternoon, as dew points fall into the 30s and 40s. Highs will still be well above normal, with readings ranging from the low to mid 60s. .LONG TERM...(Sunday night through Friday) Issued at 350 AM EST SAT FEB 24 2018 The period will begin with a surface high pressure building east into the Ohio Valley. However, a 500mb shortwave and departing 300mb jet streak will help to develop a surface low to our south. Some of the moisture and showers could move into the far southeast and kept this idea stays close to the ECMWF. Overall this should be light and we will see drying conditions in the afternoon hours, as the surface high firmly sets up across the Ohio Valley. This surface high pressure and some subtle 500mb riding will dominate through Tuesday evening. Tuesday will be quite dry in the afternoon, so did lower the dewpoints some especially in the east. By midweek the models really struggle with the upper level patterns which complicate the synoptic surface features. The initial shower activity will be the result of warm sector 850mb jet energy on Wednesday. After this a split flow pattern develops in the 00Z ECMWF and the 00z GFS depicts coupling of the two streams. This leads to varying solutions regarding the evolution of surface lows, with much different timing from these two models. The ECMWF has shown the most change this cycle given the two different pieces of energy versus the more coupled system seen in the previous run. Therefore could not see putting all the stock into the latest ECMWF. However,I did lean on the model blended POPs, but capped these at high likely given the varying solutions. Also opted to lean toward the lower QPF presented by WPC as a result of the varying solutions. The differing solutions will also have implications on temperatures, with the GFS showing sounding profiles that would support at least a mix of snow Thursday night. That said, thought the model blend solution capping temperatures in the 40s for lows at most locations on Friday morning was the best approach. This will keep snow out of the forecast besides Black Mountain until better agreement can be had by the various model suites. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 145 AM EST SAT FEB 24 2018 A low level jet will bring widespread showers to the area through Saturday morning. Have left out the mention of low level wind shear, as it appears marginal between 09 and 13z. Expect ceilings/visibilities to drop down to MVFR/IFR at times. Showers will become more scattered in nature in the afternoon, as a warm front lifts north of the area. Surface winds will be variable at around 5 kts through Saturday morning, before becoming southwest at around 10 kts, with gusts of 15 to 20 kts at times during the afternoon and into the evening hours. && .JKL WATCHES/WARNINGS/ADVISORIES... Flood Watch through Sunday morning for KYZ044-050>052. && $$ SHORT TERM...GEOGERIAN LONG TERM...DJ AVIATION...GEOGERIAN

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