Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 030257 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 957 PM EST Fri Dec 2 2016 .UPDATE... Issued at 957 PM EST FRI DEC 2 2016 IR SAT does show the Stratocu deck has been sinking south over the past few hours and therefore tried to match up the grids with this idea. This has made the hourly temps quite tricky, as you have lower deck north and east and high deck creeping into the SW. Tried to trend somewhat away from the typical diurnal curve given this more unorthodox temp progression. In terms of the SKY did opt to also increase coverage in the east through Sat morning just given the overall trends and model sounding data. Other edits were more minor and related to overall trends. UPDATE Issued at 632 PM EST FRI DEC 2 2016 The stratocu challenge remains this hour with models continuing to struggling with timing. Opted to back off the clouds given the struggle and move these in slowly through the evening. Overall the confidence remains low at this point on how this will evolve. Also opted to lower valley temps where clear skies and decoupling has already brought Quicksand Mesonet site to 36 degrees this hour. Otherwise most the changes to the grids were minor, and will continue to update/monitor trends with the previously mentioned elements through the night. && .SHORT TERM...(This evening through Saturday night) Issued at 309 PM EST FRI DEC 2 2016 The challenge in the near term portion of the forecast is how to best handle the low cloud deck that covers the northern part of the forecast area. Earlier today the cloud deck had been making good southward progress, but this has temporarily halted. However, winds at 925 mb to 850 mb are still forecast to continue to veer and become more northwest as the evening progresses. Based on this and with support from short term model sounding forecasts we are still expecting the cloud deck to make southward progress tonight. There is some question about how far southwest the cloud deck will eventually extend. The clouds will impact overnight minimum temperatures, and with more clouds in the northeast will have warmer overnight lows there and colder temperatures in the southwest part of the forecast area. The uncertainty of the extent of the cloud cover later tonight into Saturday results in a lower confidence forecast than normal for temperatures for the near term portion of the forecast. On Saturday night the focus of the forecast shifts to developing precipitation in advance of a mid level short wave trough. Current model trends, especially with a view to soundings and cross sections point towards less chance of any snowflakes mixing in late Saturday night and early Sunday morning. The new forecast will decrease the duration and coverage area for any light rain snow mix possibilities, but will still include it for now in the north. However if current trends continue complete removal of any mention of snow mixing with the rain could occur in future forecasts. .LONG TERM...(Sunday through Friday) Issued at 309 PM EST FRI DEC 2 2016 Active weather is store during the extended period, as a series of weather systems are poised to bring multiple rounds of precipitation to eastern Kentucky. The first round of precip is expected Sunday and Sunday night, as two phased areas of low pressure aloft move across the region. One system is expected to move across the northern CONUS, while a second area of low pressure is still forecast to traverse the Gulf Coast. The area between these two weather systems is where our precipitation will come from to end the weekend and kick off the upcoming work week. Some locations north of the Hal Rogers Parkway may see a few snow flakes mixing with the rain early Sunday morning, but the latest model data is suggesting that most precipitation will be in the form of rain Sunday. The best chance for precipitation looks to be Sunday afternoon and evening, as the southern stream system moves by to our south, bringing Gulf of Mexico moisture into the area. This initial round of precipitation should be coming to and end early Monday morning, as the causative weather systems move off to our east. After a brief respite, a second more potent area of low pressure is expected to move toward the area out of the southern Plains Monday afternoon and night. This system will be more intense and have more moisture with it than the first one. In fact, widespread soaking rainfall is expected across all of eastern Kentucky Monday night and Tuesday. Energy and moisture from this system will allow for isolated to scattered rain showers to linger across the area through Wednesday afternoon. There will be another lull in the weather Wednesday afternoon and evening, as a weak ridge of high pressure briefly settles over the region. A third and final weather system is then expected to move quickly out of the northern Plains and across the Great Lakes and Ohio River Valley regions Wednesday night through Thursday night. Based on the latest model temperature profiles, it appears that this mid to late week system will have a bit more warm air with it, so the precipitation forecast will feature less snow and much smaller snow accumulations for Wednesday night and early Thursday then previously forecast. There should be periods of rain/snow mix and snow late Wednesday night into Thursday morning. Most of the day on Thursday should feature all rain, as warmer air filters into the area. Another push of cold air may bring another round of rain snow mix and some isolated light snow showers to eastern Kentucky late Thursday night into Friday, as the upper level low departs to our east. Little if any snow accumulation is expected. Temperatures through the period will vary from below normal to above normal depending on the day. Sunday and Thursday should see highs in the 40s across the area, while Tuesday and Wednesday will most likely see highs in the 50s. The coldest day of the week could be Friday, when the mercury may only climb into the 30s area wide. Nightly lows will generally be in the 30s and 40s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 621 PM EST FRI DEC 2 2016 Models have struggled with this stratocu deck and continue to struggle this evening. Overall have slowed this deck down and attempted to trend this with the actually VIS SAT data. Low confidence in this deck making into the SW sites and actually opted to only bring a SCT 5kft deck into SME. The challenge will also be how much does this deck in fact remain in the area for Saturday. Right now will lift this deck to VFR by 15Z and then more clouds will move in from the south by late in the day. This however will be more of a build down of moisture beyond the TAF period based on time heights and forecast soundings. Winds will remain light through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...SBH LONG TERM...AR AVIATION...DJ

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