597 FXUS63 KLMK 150524 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 124 AM EDT Tue Jul 15 2025 ...Updated Aviation Discussion... .KEY MESSAGES... * Remaining hot and humid this week with more scattered rain and storm chances each day. Heavy rain, gusty winds, and lightning will be the main threats. && .UPDATE... Issued at 1153 PM EDT Mon Jul 14 2025 Subtle surface boundary was noted from roughly Evansville, IN southeast through Fort Knox and stretches eastward to just south of Richmond, KY. Few showers and storms continue to fire along this boundary as the nocturnal low-level jet increases slightly across the region. Main corridor of convection looks to continue for the next few hours across Washington/Mercer/Boyle/Lincoln/Marion counties. Severe threat remains very low with this activity. However, with PWATs over 2 inches across the region, locally heavy rainfall will be the primary threat over the next few hours. Did a quick update to increase PoPs and QPF across portions of east- central KY overnight to account for localized activity. Updated issued at 957 PM EDT Jul 14 2025 Afternoon convection was limited today with weak lapse rates and a lack of any strong forcing over the area. Still seeing a few isolated showers, but lightning remains very limited. Expect that trend to continue overnight given a juicy air mass with PWATs over 2 inches, but coverage doesn`t get anywhere close to 20 percent. No changes planned to the going forecast. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 356 PM EDT Mon Jul 14 2025 This Afternoon and Evening... Scattered clusters of showers and thunderstorms have developed across the area this afternoon, with the stratus layer that was along a decaying front now scattering out into a stratocu field over central KY and southern IN. Temperatures have warmed into the mid 80s in most areas, with dewpoints typically in the low-to-mid 70s as low-level moisture pools along the front. This has allowed for modest amounts of instability, generally between 1500-2000 J/kg MLCAPE on latest SPC mesoanalysis. Latest hi-res guidance suggests that shower/storm coverage should remain isolated to scattered this afternoon, especially as the mid-level wave associated with the sfc front lifts to the north and east. The greatest coverage of showers and storms according to CAMs will be over southern KY, with coverage decreasing around sunset as we lose sfc-based instability. Tonight... The muggy air mass overhead will keep temperatures mild tonight as low-level moisture settles after sunset. While an isolated shower is possible across southwestern portions of the CWA, most of the area should remain dry overnight. The main forecast challenge will be if/how much fog develops tonight. While at least patchy fog looks like a good bet for rural areas and valleys, there is still some uncertainty if lingering cloud cover will keep fog from being more widespread. For what it`s worth, the strongest fog signal in the 12Z HREF guidance extends across the Bluegrass region and into eastern KY, with more of valley fog signal present elsewhere. Lows Tuesday morning should end up in the low 70s in most locations, with a few upper 60s possible in the cooler valleys. Tuesday... No significant changes are expected in the large scale pattern for tomorrow, with the warm and humid air mass remaining in place. Short range models depict another convectively-enhanced mid-level disturbance moving from the ArkLaTex to near the confluence of the Ohio and Mississippi River tomorrow. This should provide some additional support for showers and thunderstorms during the afternoon, with several hi-res models showing greater coverage in the vicinity of the MCV. Deep-layer shear values will still be fairly weak on the order of 15 kt, so mostly disorganized showers and storms are expected, with water-loaded stronger cells producing gusty winds, heavy rainfall, and lightning. While cells should move at around 15-20 mph, areas which have greater residence time of heavy rain could see localized flooding. Highs on Tuesday should be fairly similar to today in the upper 80s and lower 90s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 356 PM EDT Mon Jul 14 2025 Medium-range guidance consensus continues to show a fairly static synoptic pattern late this week and through the weekend as a belt of faster zonal flow continues across the northern US and southern Canada while ridging shifts back and forth between a typical Bermuda high setup and a southern Plains setup. With no large-scale forcing to shift the pattern, like the way the previous forecast describes the "rinse and repeat" setup, as each day should be fairly similar weather-wise. In general, expect seasonally hot and humid conditions with temperatures ranging from the upper 80s to the mid 90s for highs and low-to-mid 70s for lows. With dewpoints remaining in the low-to-mid 70s through the extended period, afternoon heat indices should peak in the upper 90s and lower 100s, with the highest heat indices expected Thursday afternoon. While conditions should be fairly uncomfortable each afternoon, expected heat indices aren`t out of the ordinary for mid July and should be below advisory criteria. Daily scattered shower and thunderstorm chances will peak in the afternoon and evening and diminish for the nighttime and morning hours. With the band of stronger mid- and upper-level westerlies staying well to the north, wind shear will remain weak, and convection will remain largely disorganized. Coverage will likely be variable from day-to-day as increased coverage would be expected in the vicinity of smaller-scale shortwaves in the zonal flow aloft. In general, garden-variety showers and storms with localized gusty winds and heavy rainfall can be expected each day. The main threats from these storms should be localized flash flooding due to longer residence time of heavy rainfall. && .AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 124 AM EDT Tue Jul 15 2025 Notable surface boundary was located from just north of EVV to near FTK and then extends east over toward RGA. Scattered convection continues along this boundary this morning with the most concentrated area of convection just west of RGA. It`s possible that a few showers may reach SDF in the next 60-90 min as this boundary lifts northward. Rather stagnant airmass is expected to continue overnight with patchy fog developing across the region. Overall, most locations look to remain VFR overnight, though a drop to MVFR vsbys could occur with the patchy fog. Any fog that develops will be short- lived with VFR conditions returning to the region with a southwest breeze for much of Tuesday. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE.......MJ SHORT TERM...CSG LONG TERM....CSG AVIATION.....MJ