070 FXUS63 KLMK 250121 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 921 PM EDT Mon Aug 24 2020 .Forecast Update... Issued at 921 PM EDT Mon Aug 24 2020 Tonight will be another warm, still, muggy night under mostly clear skies with patchy fog possible toward dawn. High pressure is in control and the forecast looks good, no significant changes needed. && .Short Term...(This evening through Tuesday) Issued at 305 PM EDT Mon Aug 24 2020 A compact mid-level trough is swinging southeast over the Ohio Valley this afternoon. This wave is interacting with a deep moisture gradient over southeast KY and Middle TN to produce a narrow band of scattered convection. Haven't even really seen much lightning with scattered showers mostly confined to Cumberland and Clinton counties in the far southeast. That activity is expected to drift southeast with time into TN over the next few hours. Further north and west, most areas will continue to stay dry due to a lack of forcing. Still would not completely rule out a couple isolated storms near/north of I-64 through mid-evening, because there is still decent moisture in place west of the aforementioned shortwave. SCT diurnal cu will quickly diminish this evening, leaving mostly clear skies overnight. Patchy fog looks likely Tuesday morning, with a brief period of dense fog possible in the river valleys shortly before and around sunrise. Lows will range from the mid 60s to around 70. The most notable thing about Tuesday will be the heat and humidity. Going for highs in the 89-94 F range, but afternoon heat indices of 95-100 F will be common across central KY and southern IN. Tuesday will be characterized by weak ridging at the sfc and aloft. The tropical moisture plume over the Southeast will attempt to begin to inch northward over the TN Valley, but any meaningful rains will stay well south of the KY border. Separately, a convective system does appear likely to dive southeast from Lower MI across northern IN and Ohio during the day. There is a remote chance outflow from that convection could trigger new development over extreme SW Ohio, which could then drift into northern KY tomorrow evening. But decided to cap PoPs at 10 percent. Most global models and CAMs support a dry forecast. .Long Term...(Tuesday night through Monday) Issued at 310 PM EDT Mon Aug 24 2020 Unsettled weather is expected for much of the long term period as attention turns to Tropical Storm Laura. Current model guidance suggests Laura will strengthen into a hurricane by Tuesday evening before making landfall near the TX/LA border sometime Wednesday night. Laura is then forecast to travel northward across the Lower MS Valley on Thursday before turning to the northeast/east and ejecting across the TN/OH Valleys as a Tropical Depression on Friday. Relatively quiet weather is expected for Wednesday as high pressure continues to nudge in from the southeast. However, may see some showers and storms develop across southern KY during the afternoon and evening hours as a slug of Gulf moisture pushes into the region. Temperatures will be quite warm and humid, with highs in the upper 80s to lower 90s and heat indices reaching into the mid to upper 90s. Scattered showers and storms will then be possible across much of the forecast area on Thursday as the tropical airmass continues to spread over the area ahead of TS Laura. Under increased cloud coverage, temperatures will stay a touch cooler, topping out in the mid to upper 80s. There remains a decent amount of uncertainty for the Friday and beyond period as we wait for better model consensus on the evolution/path/strength of TS Laura as she makes landfall and continues inland. Moving into Friday/Saturday, the 12Z ECMWF and GFS model runs have trended a little slower and farther south with the track of Laura's remnants, now moving the remnants along closer to the KY/TN border. The ECMWF also continues to keep the remnants of Laura stronger than the GFS does as she moves into the OH/TN Valleys. Overall though, best timing for widespread precipitation looks to be in the Friday to Saturday timeframe based on current guidance. Soundings suggest a very moist profile with PWATs roughly in the 2.10 to 2.40 inch range and a deep warm cloud layer of 4 to 5 km. This will lead to heavy rainfall potential with 2-4 inches of precipitation possible across the area, which will also increase the chances for flash flooding issues to arise. Depending on the strength of Laura as she moves through the region, gusty winds may also become an issue. Beyond Saturday, rain chances will continue as a frontal boundary is expected to push southward across the area. && .Aviation...(00Z TAF Issuance) Issued at 632 PM EDT Mon Aug 24 2020 Clear skies and mostly calm winds can be expected tonight with surface high pressure ridging from the mid-Atlantic Coast to the Ozarks. Patchy fog will form during the early morning hours. Tomorrow the high will weaken, but effects from tropical systems will stay to our south...and thunderstorms diving from the Great Lakes to the upper Ohio Valley should remain to our northeast. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...13 Short Term...EBW Long Term...JML Aviation...13