638 FXUS63 KLMK 180959 AFDLMKArea Forecast Discussion National Weather Service Louisville KY 559 AM EDT Thu Sep 18 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Dry weather is expected to continue through Friday, with ongoing abnormally dry and moderate drought conditions likely to persist. Saturday will be mostly dry.
* Daytime temperatures will be unseasonably warm with highs in the upper 80s to lower 90s. However, overnight low temperatures will be near normal with low 60s expected.
* Rain chances return Sunday through mid next week. Unfortunately, rainfall amounts are expected to be light and unlikely to improve overall drought conditions at this time.
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.SHORT TERM /THROUGH FRIDAY/... Issued at 246 AM EDT Thu Sep 18 2025
High pressure and ridging remain over the region in the short term. This will keep continued dry and warm conditions in place through Friday. We will see large diurnal temperature swings with low temperatures in the upper 50s and low 60s and highs in the upper 80s and low 90s. Very dry profiles aloft and ample mixing up to 750mb will allow for some dry air mix down in the afternoons today and Friday. Expecting to see RH levels dip into the 23-28% range during peak heating hours. Winds aloft are light, thus not expecting surface winds to exceed 5-9mph. A few to scattered cumulus field is likely to develop in the afternoons.
In the evening, skies will clear and winds will become calm to light. Some patchy fog will be possible in the river valley areas in the early morning.
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.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 246 AM EDT Thu Sep 18 2025
===== Friday Night - Wednesday =====
Troughing over the northern Plains will begin to shift east Friday night into Saturday. Vorticity riding along the troughing will move through the lower Ohio Valley. The showers and storms associated with this vorticity, will quickly dissipate as there is so much dry air over the region at this time. Could see a few sprinkles or light rain over the far western counties, however, Friday night should remain dry. Most guidance shows some decaying convection moving into the region, but similar to last weekend, there is just too much dry air in place and models aren`t completely picking up on that.
Through the weekend, this troughing will remain over the Midwest bringing several shortwave disturbances into the region. Saturday has a better chance to remain dry, since southerly flow will not return until Sunday.
Sunday, moisture will increase over the region as better troughing and large scale ascent moves towards the region. These features will increase shower and storm chances Sunday through mid next week. Guidance continues to keep troughing northwest of the region, which will bring the highest chances of precip over the northwest and tapering lower to the southeast portions of the region. LREF probabilities show a 50-60% chance of exceeding 0.5 inches of rainfall and a 20-30% chance of exceeding 1.0 inches of rainfall over the far northwestern portions of the region during this timeframe.
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.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/... Issued at 558 AM EDT Thu Sep 18 2025
VFR conditions are expected through the forecast period. Some patchy fog is possible in the morning, especially over the Lake Cumberland region. Winds will remain light and variable over the region. Skies should remain mostly clear through the period, however, FEW-SCT cumulus is possible in the afternoon. In the evening, winds will become calm and skies will clear.
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.LMK WATCHES/WARNINGS/ADVISORIES... KY...Air Quality Alert until midnight EDT tonight for KYZ029>031. IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for INZ076>079-083-084-089>092.
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SHORT TERM...SRW LONG TERM...SRW AVIATION...SRW
NWS LMK Office Area Forecast Discussion