Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 141527 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1027 AM EST Sat Jan 14 2017 .UPDATE... Issued at 1027 AM EST SAT JAN 14 2017 Based on latest radar trends and most recent near term model data have updated hourly NDFD to bring a quicker increase in shower coverage today. The ridges remain draped in fog late this morning with visibility still under a quarter mile here at the National Weather Service Office, but visibility is showing an upward trend at other sites, with London even up to 10 miles. UPDATE Issued at 752 AM EST SAT JAN 14 2017 This update realigns POP & weather grids this morning to account for radar trends in the northern part of the area. Overall, the forecast is on track and very few changes were made. && .SHORT TERM...(Today through Sunday) Issued at 430 AM EST SAT JAN 14 2017 A frontal boundary was stalled in the southeast CONUS early this morning. A north/south temperature gradient was present over the JKL forecast area. Overrunning moisture was leading to extensive clouds, fog, and areas of precip north of the frontal boundary. The general scenario is expected to hold through the period. Weak impulses will determine when/where precip is more concentrated. The GFS and NAM, and ECMWF all show general agreement on precip, and see no reason to stray from a model blend to handle it. That being said, aside from the showers skimming our northern counties this morning, there will be two upticks in precip. The most significant one will be this afternoon and early evening, and the second and more minor one will be Sunday afternoon. A dense fog advisory was discussed with neighboring offices. While the fog has been dense in a few place, it`s mainly been on the taller ridges. Elsewhere, reported visibility has mostly been greater than 1/2 mile. That being the case, have held off on an advisory. However, the situation will continue to be monitored, and an advisory may be necessary if dense fog becomes more widespread. .LONG TERM...(Sunday night through Friday) Issued at 430 AM EST SAT JAN 14 2017 The period will begin with baroclinic zone remaining somewhere near the region, and this will lift north as more of a warm front by Monday. Overall keep better POPs across the north Sunday night and slowly wane POPs through Monday. There will be a general lull in the precip on Monday before low pressure system across the Southern Plains ejects into the Western Great Lakes by the time we get to Monday night. There will probably be some showers develop ahead of the attendant cold front late Monday night into Tuesday. This is where the guidance begins to diverge in the upper level synoptic pattern leading to surface feature inconsistencies. That said, the 00Z GFS operational run phases the southern stream trough and consequently deepening the northern stream trough Monday night into Tuesday night. This northern stream trough then negatively tilts leading to faster more progressive frontal passage. Meanwhile the ECMWF/Canadian are slower as they dig a northern stream spoke of energy across the Midwest and develop another low along the said frontal boundary. This slower solution would lead to longer resonance period of moisture streaming across the region. Thus the slower solution would lead to additional precip in the east going into early Wednesday. WPC would suggest this will be a open wave and not sure this will pan out given the more amplified solutions offered by most of the model suites including their ensembles. Overall too soon to call either solution, but we could see some localized flooding issues especially considering the antecedent wet conditions. Also there is some indication of seeing convection which would further support localized flooding issues. This system will pull east by Wednesday afternoon and evening time frame with either solution offered. Therefore Thursday looks to be dry at this stage of the forecast process. There is then another Baja upper level low that ejects into the Southern Plains by Thursday night and not surprising the models also diverge here too. Right now will keep close to the blend given the varying synoptic solutions, and this would support better POPs in the Lake Cumberland region. Temperatures through the period will remain above normal and at times well above normal. Overall period offers one cooler day by Wednesday in the wake of the front, however temperature remain 10 to 15 degrees above normal for afternoon highs. Some of these days will also flirt with record high temperatures for this time of year. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 714 AM EST SAT JAN 14 2017 Initial conditions were IFR or worse area wide, with both ceiling and visibility being problems. While some improvement in visibility is expected for the afternoon, ceilings should remain low, and conditions are not forecast to improve beyond IFR any time in the period. In addition, light rain is expected for much of the area this afternoon. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...HAL LONG TERM...DJ AVIATION...HAL

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