Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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409 FXUS63 KLMK 060516 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 116 AM EDT Thu Jun 6 2024 ...Updated Aviation Discussion... .KEY MESSAGES... * Scattered showers and storms likely this afternoon and evening. A few strong to severe storms are possible. Gusty winds and torrential rainfall will be the main threats. * Drier weather and cooler temperatures are favored late week into the first half of this coming weekend. && .UPDATE... Issued at 857 PM EDT Wed Jun 5 2024 Moderate to heavy rain showers ahead of an approaching cold front currently working into western IN will continue to work across the area this evening and overnight. There were a few isolated storms, mainly across Hardin and into Nelson Counties this evening that took advantage of better effective shear (30 kts) and higher MLCAPE 1000- 1500 J/Kg but more recent analysis shows CAPE values dropping as we continue to lose the daytime heating. As the activity continues to move more to the east slowly this evening, we may see convection become more elevated. PWAT values remain between 1.70" to 1.90" ahead of the boundary thanks to good moisture pooling ahead of the boundary. This makes heavy rain and some localized flooding the main concern with any storms that form later this evening and overnight. Given some of the uncertainty of where activity would fire this evening, previous forecast had a wide swath of 50-60 PoPs across the CWA. Now that we see how activity has been developing, went ahead and cleaned up some of the PoPs to better reflect the ongoing situation across our CWA with higher PoPs across southern IN and along the OH with lower PoPs right now to the south and east. Then we increase PoPs towards the east and south as the boundary works closer and we see more development overnight. Other than that, not other changes have been made to the forecast and updated product will be pushed out here shortly. && .SHORT TERM /THROUGH FRIDAY/... Issued at 333 PM EDT Wed Jun 5 2024 Afternoon satellite imagery shows partly to mostly cloudy skies across the region. Earlier MCV over southern KY continues to churn eastward helping firing convection over mainly eastern KY. In the wake of the MCV, some partial clearing is trying to take place across portions of central KY (I-65 corridor) ahead of an approaching cold front. Afternoon temperatures were generally in the low-mid 70s in the cloud cover. In areas that had partially cleared, temps had warmed back into the upper 70s to around 80. Some low-mid 80s were located down in the Pennyrile region of western KY. Mesoscale analysis shows instability building across the central part of the region with MLCAPE values in the 800-1200 J/kg range with about 30kts of bulk shear. Low and mid-level lapse rates were still quite meager with rates running around 6 C/km. PWAT values were quite high with widespread 1.7 to 1.8" values, so we have plenty of primo juice to work with. For the remainder of the afternoon, additional forcing for convection remains rather nebulous in the wake of the passing MCV. Frontal forcing remains well to our northwest for now. Some additional insolation may result in an uptick of convection along differential heating boundaries, so will keep isolated/scattered PoP coverage going into the evening hours. Any strong storm will be capable of producing torrential rainfall, gusty winds, and frequent lightning. Localized flash flooding will be a threat, especially in areas that have seen recent rainfall. Moving into the evening hours, surface frontal boundary to our northwest will sink southward into the region. Majority of the 12Z CAMs suggested an uptick in convection along and just ahead of the front and we`re already seeing the start of that across central/southern IL. Early evening coverage looks to be most concentrated across southern IN back into southwest KY. This activity should then drop southward into north-central/east-central KY this evening while weakening as we loose heating/instability. The storms this evening could be on the strong side with torrential rainfall, gusty winds, and frequent lightning being the main threats. We`ll have to be on guard for some localized flash flooding given that these storms should be efficient rain producers. The risk of flooding will be highest where storms tend to train over the same locations. Overnight, the front will continue to push south/southeastward with rain chances ending from NW to SE. Overnight lows will cool into the lower 60s over southern IN and in the mid-upper 60s over much of central/eastern KY. For Thursday, overnight cold front will continue to push southeast during the morning hours. We`ll have some lingering low-level moisture that will be in place during the morning hours. A secondary frontal boundary will drop into the region during the afternoon and may spark an isolated shower or two, mainly across our far eastern counties. Highs for Thursday will be near normal with lower-middle 80s expected. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 333 PM EDT Wed Jun 5 2024 Thursday Night through Friday Night... A sfc cold front will be well southeast of the area by Thursday night, with northwesterly flow at all levels. Cooler, drier air filters into the region Thursday night with temperatures falling into the mid/upper 50s. Dry NW flow continues through Friday with high pressure centered over the southern Plains and Lower MS Valley. Expect sunny skies and lower humidity (sfc dewpoints in the lower 50s). Afternoon highs will reach the 75-80 degree range. It will be a bit breezy with NW winds of 10-15 mph, gusting to 20-30 mph. Friday night temperatures will be on the cool side of normal with lows in the 50s. This Weekend into Early Next Week... The upper level pattern deamplifies a bit Saturday with ridging aloft now centered over the western Gulf Coast. An upper level shortwave trough is forecast to rotate southeast over the Upper Midwest and Great Lakes. Weak low pressure spinning up over the southern Plains will also help lead to strengthening SW return flow from the southern Plains east across the Mid-MS and Lower OH Valleys. This will result in modest moisture advection into the OH Valley, but the atmosphere looks to remain rather stable. We could see some weakening convection attempt to push into central or southern KY by evening, but a largely dry day appears likely at this time. Afternoon highs will be in the mid/upper 70s in most areas. The upper level trough over the Great Lakes deepens as it drops south late in the weekend, and a weak sfc cold front is forecast to drop south through southern IN and central KY. Rainfall chances tick upward late Saturday night into Sunday, especially across southern KY. However, rainfall totals are forecast to be relatively light (generally a quarter-inch or less). Some areas across southern IN and north-central KY may not see much rain at all during this time frame. Another push of cool, dry air advection from the north will likely yield fair weather heading into early next week. Highs in the mid/upper 70s look likely for Monday, perhaps with a couple spots near 80 F. Most areas will approach 80 degrees by Tuesday. && .AVIATION /06Z TAFS THROUGH 12Z FRIDAY/... Issued at 116 AM EDT Thu Jun 6 2024 A cold front is located over the region early this morning, with a disorganized line of showers and one or two rumbles of thunder extending along a BWG-LEX line at this time. This area of rain along the front will gradually push to the east later this morning, clearing BWG and LEX within the next 2-3 hours, and clearing RGA by 10-11Z. Occasional visibility reductions will be possible in any heavier shower, with temporary IFR/MVFR conditions possible at BWG, LEX, and RGA over the next few hours. Across all sites, there is potential for reduced visibilities and/or reduced ceilings later this morning. At LEX/BWG/RGA, would lean toward low stratus given persistent light low-level breeze overnight. At SDF, it is quite a challenging forecast through 12Z this morning as the deeper moisture and stratus should make it just southeast before settling into MVFR levels; however, the back edge of the low clouds will be close enough that brief MVFR CIGs are still possible. At HNB, while deeper moisture should be far enough to the southeast to limit low stratus, fog potential will be present due to weaker winds. Would expect most if not all sites (with the possible exception of SDF) to bounce between VFR/MVFR/IFR between 08- 13Z this morning, and the forecast is low confidence between now and then. Later this morning, confidence increases in a return to VFR conditions as drier air aloft starts to work in behind the cold front. Winds will increase out of the west later today, with sustained winds around 10 kt and gusts to around 20 kt during the late morning and afternoon hours. A secondary front dropping through the area will bring an increase in mid-level clouds this afternoon as well as a few showers; however, substantial impacts from clouds/showers are not expected at this time. After sunset tonight, clearing skies and light westerly winds are expected through the end of the current forecast period. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...BTN SHORT TERM...MJ LONG TERM...EBW AVIATION...CSG