Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 201252 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 752 AM EST Sat Jan 20 2018 .UPDATE... Issued at 751 AM EST SAT JAN 20 2018 Temperatures have warmed a little faster than was forecast early this morning. Have rerun a temperature curve for the day, based on the observed starting point. There is no overall change to the forecast. && .SHORT TERM...(Today through Sunday) Issued at 429 AM EST SAT JAN 20 2018 Flow around high pressure over the southeast CONUS will bring warm air advection, along with an increase in low level moisture today into Sunday. The moisture is already resulting in clouds, but is very shallow and capped by a steep inversion. With time, the inversion is expected to rise and the moist layer grow deeper, but still be capped below 700 mb. Forecast soundings suggest the possibility of a few showers late tonight into Sunday, mainly over our northern counties. Temperatures will continue to trend warmer. The question is how much. Clouds will likely keep us from seeing our potential, but if there are enough breaks, readings could shoot up either day, especially with snow cover becoming more scant. .LONG TERM...(Sunday night through Friday) Issued at 355 AM EST SAT JAN 20 2018 The models are in reasonable agreement with the long wave pattern for most of the extended period. The period will begin with ridging ahead of a closed low across the Central Plains. This upper level closed low will move into the Midwest by the Monday into Monday evening. This upper low will track across the Great Lakes Monday night into Tuesday and then the pattern almost flattens briefly in the wake of the trough. Then another wave dives into the area by Thursday before a ridge axis moves out of the plains bringing height rises back into the area Friday. Sensible weather wise, we will be watching an upper level low in the Plains that will move into the Midwest Monday. A deepening area of low pressure will become vertically stacked with the upper low and track in the same fashion. The attendant cold front will move across the Tennessee and Ohio Valleys. This will bring rain showers across the region late Monday into Monday evening. The models have been in some disagreement on the speed of this system, but latest runs indicate better and better agreement on timing. The blended guidance suggests between a quarter and half an inch of total rainfall amounts and this looks reasonable. The other story will be the gusty winds ahead and behind this system as the pressure gradient increases along with a strengthening low level jet. This lead to larger adjustments from the washed out blended guidance. The front will exit east Monday night into Tuesday, but the models disagree on the amount of moisture left in the wake. Overall kept with blended guidance at this point. The forecast soundings indicate this will probably fall as snow or rain/snow mix on the backside of the boundary early Tuesday. Then we will be met with drying conditions through the remainder of the period. The temperatures will be near normal Tuesday through Wednesday night and then with the previously mentioned height rises temperatures will climb back above normal for this time of year Thursday into Friday. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 752 AM EST SAT JAN 20 2018 A cloud deck around 3K feet AGL covers most of the area, and will be rather persistent during the period. It will continue to bring low end VFR and high end MVFR conditions. South to southwest winds will pick up to around 10 kts in most places during the day. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...HAL LONG TERM...DJ AVIATION...HAL

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