Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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802 FXUS63 KJKL 120744 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 344 AM EDT Sun May 12 2024 .KEY MESSAGES... - Precipitation free weather is anticipated through Monday morning, before more unsettled weather returns. - Expect rather cool temperatures through the weekend, with milder weather then returning. && .UPDATE... Issued at 140 AM EDT SUN MAY 12 2024 Just a quick update to the forecast early this morning mainly to add in the latest obs and trends for the T/Td/Sky grids. These minor tweaks have been sent to the NDFD and web servers. UPDATE Issued at 1133 PM EDT SAT MAY 11 2024 Updated the forecast package to emphasize tonight`s ridge valley split just a bit better. Also beefed up fog across the area for the remainder of the night. CAMs and ensemble data suggest surface dew points should drop some through the overnight as drier air advects into eastern Kentucky. Seeing a hint of that in the surface obs as well. However, model guidance tends to keep Tds up through the night. Seeing some fog formation in some of the more sheltered valleys to our east. Forecast challenge is how much drier air will be able to advect into the area versus surface dew points leveling off or possible even rebounding a bit as the boundary layer continues to decouple and grow in depth. As stated before, surface dew points should rebound slightly or the drop should slow and possibly level off. As temperatures continue to drop closer to dew points, and we are beginning to see a more substantial drop off now, believe conditions will become more favorable for some fog development, particularly around or near sources of water. Have made corresponding adjustments to the forecast package for this latest line of thinking. Overnight lows looked on target for our valley locations, however, raised the ridge top temps just a couple degrees, which would be more in line with current observations at our ridgetop sites. Updated zones and grids have already been issued. UPDATE Issued at 830 PM EDT SAT MAY 11 2024 Based on the current regional radar, the threat of any shower activity over eastern Kentucky has waning quickly over the past hour. Removed PoPs for the evening update and updated hourly T/Td to capture the most recent hourly trends. With high pressure moving into the area overnight, skies will continue to clear. Difficult to say how much fog there will be overnight. With a post frontal gradient wind am inclined to forego fog. But surface dew points should rebound slightly with decoupling of the boundary layer and expect winds will slacken enough for some patchy valley fog to develop, particularly around or near sources of water. Went ahead and freshened up the zones as well. No other changes to the forecast package at this time. Updated zones and grids will be issued shortly. && .SHORT TERM...(This evening through Sunday night) Issued at 322 PM EDT SAT MAY 11 2024 Last in a train of short-wave troughs has shifted just east of our area this hour. This shift and more ridging building in should bring a period of more tranquil weather for the short term. Skies should become mostly clear tonight, allowing for another night of aurora watching should those colors swing by here again. Similar to this morning, temperatures by Sunday morning should fall into the 40s for most locations in eastern KY. High pressure crossing overhead again will mean some potential for valley fog formation. Under more sunshine Sunday, highs should reach well into the 70s, close to normal for mid May. Weak southerly flow Sunday night, as that surface high shifts southeast of the region, will mean temperatures a little warmer by Monday morning, with lows in the mid 40s to low 50s. .LONG TERM...(Monday night through Saturday) Issued at 344 AM EDT SUN MAY 12 2024 The 12/0Z suite of model solutions appear to be in slightly better agreement through the extended as compared to this time yesterday. Plains low pressure and associated trough are poised to enter the lower Ohio and Tennessee valley areas at the start of the period. This system manages to get through our area during the first 48 hours of the extended, weakening and opening up into a trough as it tracks slowly eastward. Shortwave ridging will transit the Ohio Valley late Wednesday through Thursday, providing a brief lull in the unsettled weather pattern that will dominate the extended. Phasing of northern and southern stream energy result in a trough that moves through the Ohio Valley during the last 24-36 hours of the forecast window (Fri- Sat). At the surface, two low pressure systems at the start and end of the extended will bookend surface high pressure that drifts eastward across our area Thursday. Sensible weather features generally unsettled weather through the extended with a brief pause in the weather on Thursday. Thus the extended begins with a round of rainy weather which persist through Tuesday night and Wednesday, before slowly tapering off from the northwest late Wednesday as a trailing cold front passes through eastern Kentucky. Weak instability and shear will keep any threat for severe storms in check with this first system. While increasing PWATs of 1.2-1.4 inches aren`t spectacular, there does appear to be a period elevated 850 mb moisture convergence under notable upper level divergence by Tuesday afternoon and evening just ahead of the surface low. This may lead to a period of more steady moderate rainfall for portions of eastern Kentucky. WPC has issued a Marginal risk ERO for this time frame as a result. Further out in time, high pressure does exert its influence briefly from Wednesday night into Thursday, providing a lull in the threat of rain. Meanwhile, a northern Rockies trough and Pacific low will translate eastward and phase into a deeper trough that will eventually pivot across the eastern CONUS late in the week. This second system will bring another round of showers and thunderstorms to our area Friday through Saturday. Temperatures will average above normal through the period, but more as a result of overnight lows in the 60s running 5 to 10 degrees above normal. Exception will be Wednesday night into Thursday morning as high pressure provides one night of lighter winds, and at least partially clearing which will promote decent radiative cooling, allowing temps to fall into the mid 50s across most of the area. Tried to go with a muted diurnal range for the remainder of the period because of added cloud cover and higher PoPs. Afternoon highs will run about normal overall, mid 70s on average. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) ISSUED AT 155 AM EDT SUN MAY 12 2024 VFR conditions will hold through the period with just a small potential for some of the early morning river valley fog to impact a terminal or two around dawn. Light and variable winds will pick up later this morning from the west to northwest at 5 to 10 kts. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...SHARP LONG TERM...GEERTSON/RAY AVIATION...SHARP/GREIF