123 FXUS63 KLMK 032332 AFDLMKArea Forecast Discussion National Weather Service Louisville KY 732 PM EDT Fri Oct 3 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Chance for an isolated slow-moving shower mainly along and north of I-64 through the evening hours. A few rumbles of thunder can`t be ruled out.
* Dry and warm weather continue for most through this weekend.
* Rain chances increase early next week ahead of a cold front arriving on Wednesday.
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.UPDATE... Issued at 642 PM EDT Fri Oct 3 2025
The cluster of showers and storms which meandered across portions of Washington, Floyd, Scott, Clark, and Harrison County Indiana has finally collapsed over the past 30 minutes. It appears that the area of convection ultimately ran out of real estate where there was a greater pool of available instability. Latest SDF ACARS sounding profiles suggest that it will take quite a bit of mechanical lifting to get parcels to their LFC, which is around 825 mb. While lingering outflow boundaries could provide that forcing, diminishing coverage of cu suggests that surface-based convective processes are wrapping up for the day. As a result, will carry a slight chance PoP through 00Z, but then carry a dry forecast thereafter.
The only corridor where there is lingering evidence of agitated cu is from Jefferson County, IN down to the Louisville metro, so if any additional showers were to develop, this corridor would be favored.
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.SHORT TERM /THROUGH SATURDAY/... Issued at 306 PM EDT Fri Oct 3 2025
Still hanging onto a few chain reaction showers across our NW CWA at this hour, and expect this process to continue through the late afternoon and into the evening where the combination of the highest PWATs (1.2 to 1.3") overlap with a meager instability (500 J/KG of ML CAPE) axis. As a result, the focus currently across our NW CWA will likely shift to our north central CWA by early evening. Hi-res models have latched onto isolated to widely scattered coverage of showers and a few ticks of lightning for areas N and NE of the Louisville metro for the evening, so will carry some 20-30% chances there.
It is worth noting that shower motion will be quite slow and erratic given the weak vertical wind profiles, so localized areas could pick up decent amounts of rainfall where it does rain. Overall, basin average QPF will remain quite low as you would expect, but a very isolated amount of 1" could occur for a spot that sees repeated or slow moving activity. Just as an example of this environment`s potential, HREF LPMM QPF values peak over 1" in rural Washington county IN. While the placement may not be perfect, the potential for somewhere across our north central CWA to see amounts that high seems possible.
Overall, tough call on whether to allow any thunder mention as the vertical depth of convection will be confined between a high LFC, and mid level inversion. This will put storm depth around 10 k feet. We have seen a few in-cloud pulses, so will probably carry a slight chance mention of T to go along with mainly shower mention. Will also mention that this type of cold core H5 pattern could allow for a few cold air funnels or a brief landspout to form. SPC Mesoanalysis does indicate there is some non-supercell tornado/low level stretching potential with this environment, and these parameters do look to line up with our best instability axis this afternoon, mainly north and east of the Louisville Metro. Something to watch.
Moving into tonight, any lingering convection should diminish with mostly clear and calm conditions taking hold. Good radiational cooling, and higher Tds than recent nights could allow for some fog potential, especially across our eastern CWA.
The upper ridge axis remains in control tomorrow, and we`ll see continued warm as well as dry conditions. Temps look to peak in the mid 80s, which continues to be well above normal for this time of year.
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.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 306 PM EDT Fri Oct 3 2025
The Rest Of The Weekend...
The upper ridge axis and surface high pressure continue to slide eastward through through the late weekend, settling along the East Coast. This feature will still have enough influence on our area to keep us warm and dry. Look for above normal temperatures peaking in the mid to upper 80s each day, with comfortable lows mostly in the 50s. We get some moisture return by Sunday night, so may see slightly milder lows by Monday AM in the upper 50s and low 60s.
Monday - Friday...
Monday will be a transition day from an upper pattern standpoint as the upper ridge loses influence over our area and the digging north central CONUS trough begins to win out. We`ll see Gulf moisture return on the western side of the retreating upper ridge, adding deeper moisture (higher PWATs) into our area. In addition, some subtle low level jetting begins to respond beneath an increasing mid and upper level wind profile. As a result, we could start to see some isolated to scattered shower or storm activity across the area, especially the deeper into Monday or Monday evening we get. Tuesday looks to be the highest coverage day of showers and storms, which is a slightly faster trend from yesterday`s data. By this time, the surface cold front will be approaching along with the upper trough axis and higher degree of forcing/low level moisture transport.
Given the faster trend, the Wednesday time frame looks cooler/drier with a clean cold frontal passage along with the upper trough axis swinging through. Surface high pressure begins to build in through late week, which should return us to dry conditions. The biggest change looks to be the cooler temperatures with highs only in the low to mid 70s for Thur/Fri, and some lows in the 40s and 50s each morning.
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.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/... Issued at 732 PM EDT Fri Oct 3 2025
Most of the diurnal cu has dissipated over the past hour or two, and VFR conditions/mostly clear skies are expected through early Saturday morning. Model guidance continues to go back and forth on the potential for IFR VIS (fog/mist) at LEX and RGA between 09-14Z tomorrow. Crossover temps would suggest that the potential is indeed marginal at LEX, with forecast low temps within a degree of the crossover value. Crossover analysis is actually stronger at RGA and HNB, with forecast lows 3-4 degrees below the crossover value. As a result, have gone more optimistic for VIS at LEX tomorrow morning, and have introduced mention of mist at HNB (while continuing mention at RGA).
By mid-to-late morning tomorrow, there is high confidence in a return to VFR conditions with a 3-5 kft FEW/SCT cu field developing Saturday afternoon. With high pressure nearby, winds should be fairly light, and generally east-southeasterly.
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.LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None.
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UPDATE...CSG SHORT TERM...BJS LONG TERM...BJS AVIATION...CSG
NWS LMK Office Area Forecast Discussion