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Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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993 FXUS63 KJKL 151947 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 347 PM EDT Thu Aug 15 2024 .KEY MESSAGES... - Temperatures will be quite warm this afternoon, climbing to near 90 degrees, before cooling back down closer to normal levels Friday. - Humidity, along with the possibility of showers and thunderstorms, will increase Friday and last into Saturday night. - Below normal temperatures are expected Sunday through Wednesday behind a cold front passage late Saturday night. - Showers and thunderstorms will remain possible Sunday and Monday, especially in the afternoon and early evening, with a drying trend for Tuesday into Wednesday. && .UPDATE... Issued at 1236 PM EDT THU AUG 15 2024 Another forecast update was just issued to increase hourly and maximum temperatures for today. Also removed any remaining outdated afternoon wording from the zone forecast text product. The rest of the hourly forecast elements were freshened up with the most recent obs from around the area. UPDATE Issued at 1025 AM EDT THU AUG 15 2024 Just sent out a quick forecast update to remove mention of fog from the zone forecast text product. The latest obs were used to freshen up the hourly forecast elements such as temperatures and dewpoints to establish new trends. There some noticeable differences between the hourly temperature obs the forecast values so far this morning. Will continue monitoring these trends over the next couple of hours, and might need to issue another update that deals with todays high temperatures. Will also update later to remove any outdated wording from the forecast for today. UPDATE Issued at 719 AM EDT THU AUG 15 2024 The only update needed is to increase Sky cover across the southwestern third of the forecast area with an observed increase in high clouds transported from the next disturbance approaching the area later today. Models suggest after a few hours of increased cloud cover there will be a lull in such cloud cover toward the afternoon. The grids were updated using the latest observations for initialization. && .SHORT TERM...(Today through Friday) Issued at 315 AM EDT THU AUG 15 2024 Upper ridge axis just upstream will cross eastern Kentucky today, with an upper disturbance quickly on its heels pushing a warm front northeast across the forecast area by this evening. The longwave trough begins to move into the Mississippi River Valley and Lower Ohio River Valley late tonight into Friday, with additional disturbances ramping up the low-level warm, moist advection into the region, especially after midnight, with PWs rising from near 1.5" this evening to near 2" Friday morning. Will thus have gradually increasing PoPs and QPF moving in from the west beginning around or shortly after midnight tonight and increasing through the pre-dawn and morning hours. Instability looks rather limited until Friday afternoon, so thinking the initial push of precipitation will mostly be in the form of showers, some producing intense yet brief downpours. For this reason, the Probability of Thunder grids were lowered at least one category through the 18z Friday, with additional lesser reductions in the afternoon. Models suggest an initial round of showers and a few storms moving across the area during the Friday morning period, though there are significant inconsistencies as to whether this activity arrives before dawn or after. After this initial morning round, partial clearing in the afternoon combined with a humid and weakly unstable environment should promote another round of showers and thunderstorms from the afternoon into the early evening hours. As for the temperature forecast, expect the warmest readings of the week as weak warm advection occurs under light southwest winds, with highs in the upper 80s to lower 90s. Warm conditions are expected tonight as warm moist advection increases significantly through the night, with lows in the upper 60s to around 70 degrees. Friday`s highs will be somewhat dependent on timing of disturbances and associated disturbances and cloud cover, but mid-80s seem like the most likely outcome, but with increased humidity resulting in heat indices in the mid-90s for many locations. .LONG TERM...(Saturday through Thursday) Issued at 347 PM EDT THU AUG 15 2024 There is good agreement among the ensemble and deterministic solutions for an upper low to push across the Great Lakes, with the trough axis swinging through the Ohio Valley. This coupled with a nearby frontal boundary will keep the weather active to begin the period. Even so, the overall evolution in convection remains in question, as you could begin the day at times with early morning convection. This will certainly play a roll into how much instability can be recovered in the afternoon hours. The EFI does show decent signal for the climatologically significant combination of CAPE and shear on Saturday, but when looking at CAPE alone it was a much lesser signal. This means the shear seems to be driving the values up more and the jet energy noted in the various solutions is one that would support deeper layer shear. Given the uncertainties mentioned, SPC did keep a marginal risk going for Saturday. In terms of flooding, the concern here would be places that can see multiple iterations of storms, so overall threat right now is lower. Outside this expect near normal temperatures (mid to upper 80s) Saturday depending on cloud cover. This trough axis will continue to swig through the area and lower heights some as it does. This will keep the weather active through Monday. The highest chances of rain will be Sunday when chances of rain peak at around 50-90 percent particularly in the far eastern parts of eastern Kentucky. By Monday, afternoon highs will be running around 10 degrees below normal, with highs in the mid to upper 70s in most locations. A cold front or post frontal trough will user in much dryer air by Tuesday. The PWATs will be running in the 25th percentile range for this time of year at around 0.75 inches. There is good agreement on an area of high pressure pushing into the Great Lakes providing northerly flow at the surface and will lead a much cooler night Tuesday into Wednesday morning. The dewpoints are expected to mix out well under deep mixing on Tuesday and did adjust this down given the usually too hot NBM deterministic toward the 10th percentile. Given this lowered valleys into the upper 40s to lower 50s for overnight lows by Wednesday morning. This cooler valley trend was also noted in the COOP MOS. We will begin to rebound through the week to near normal for afternoon highs, with overnight lows remaining in the low to mid 50s in most cases. The other good news is it should be nice and dry Tuesday into Thursday under the northerly flow and lower PWAT values. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 140 PM EDT THU AUG 15 2024 VFR conditions expected to prevail through out the TAF period. SCT cumulus clouds have sprouted over the area this afternoon, and will remain in place through sunset. Overnight, we will see cloud cover gradually increasing to SCT to BKN by late tonight, as an area of low pressure moves in from the west. Scattered rain showers will begin to affect SYM, LOZ, and SME between 11 and 13Z Friday and JKL and SJS between 12 and 14Z. A few thunderstorms will also begin firing toward the end of the TAF period. Winds should remain light and variable the rest of today and tonight, but will shift to the south or southwest early Friday with values of around 7kts. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...CMC LONG TERM...DJ AVIATION...AR