539 FXUS63 KLMK 080504 AFDLMKArea Forecast Discussion National Weather Service Louisville KY 104 AM EDT Wed Oct 8 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Rain will taper this evening, though a few isolated showers may linger into the nighttime hours tonight.
* Cooler, more seasonal temperatures arrive tomorrow, continuing through the weekend. Dry conditions are expected through the weekend.
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.UPDATE... Issued at 904 PM EDT Tue Oct 7 2025
Current KLVX Radar is showing a few isolated in a line stretching from Jefferson Co. IN through Clark Co. IN southwest towards Grayson Co. KY to Todd Co. KY. These showers are much weaker than they were before sunset but they are firing along the cold front that is crossing central KY this evening. While most of the activity is isolated in nature. given that these are firing along the boundary, feel our current POPs look good through the rest of the evening and overnight. Low stratus over central IN will drop southward overnight along with low stratus currently over the eastern portion of our CWA. Clouds and even some pocket of drizzle is possible through the overnight and into the early morning hours but confidence is not that high. Winds will also begin to increase out of the north, and you can see this already occurring over in western KY per the Kentucky Mesonet. The rest of the forecast looks to be on track and any additional rain that may fall will not lead to any additional flooding issues overnight.
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.SHORT TERM /THROUGH THURSDAY/... Issued at 417 PM EDT Tue Oct 7 2025
This afternoon, sfc low pressure is tracking across central KY, moving east as a broader sfc cold front sweeps through the region. Ahead of the front, persistent 30-35 kt southerly flow in the low-to- mid levels has led to PW values near 2" along and just ahead of the sfc low center. Broad isentropic upglide, llvl convergence along an effective warm front, and embedded convection has led to a band of moderate to heavy showers and storms which has pushed along the I-64 corridor over the past 12 hours, bringing widespread rainfall amounts in excess of 2" and a corridor of 4-6" of rain, overperforming expectations. Across south central KY, rainfall amounts have underperformed as a lack of an organizing boundary has kept rain showers more scattered and kept precipitation totals at or less than 1".
As we head through the rest of the afternoon, the heaviest rain should push toward the Appalachians as winds swing around to the N and NW with FROPA. Some scattering in the low stratus behind the front has allowed for modest destabilization to occur as llvl lapse rates steepen, with 1000-1500 J/kg SBCAPE developing across the Wabash Valley. Scattered showers, and possibly an isolated storm, will develop along the cold front, pushing off to the south and east through the evening hours. Precipitation amounts with these showers should be light enough as to not exacerbate ongoing flooding, with QPF totals generally 0.25" or less.
Tonight, drier air will begin to work in as cold advection sets in in the post-frontal environment. However, stubborn llvl moisture will likely hang around in the form of a stratus layer overnight, with this stratus not expected to clear from north to south until Wednesday morning. This stratus layer may briefly be deep enough for patchy drizzle or mist to form, especially across eastern portions of the CWA. Otherwise, mostly dry conditions are expected tonight. Temperatures should range from around 50 tomorrow morning across southern IN to around 60 along the KY/TN border.
By sunrise Wednesday, low clouds should begin to scatter out, with mostly sunny skies returning for all by early afternoon. A seasonally strong pressure gradient in the wake of the cold front should allow for robust cold advection into the area, keeping temperatures in the low-to-mid 70s in spite of ample sunshine. N/NE winds will be gusty at times, with sustained winds of around 10 to 15 mph and wind gusts to 25 mph expected late morning into the afternoon.
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.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Issued at 417 PM EDT Tue Oct 7 2025
Wednesday Night through Friday Night...
High pressure will settle just to the north of the region Wednesday night into Thursday as drier northeasterly flow continues to filter in behind the departing cold front. The cP air mass which moves into the region should be the coolest one we`ve seen so far this fall, sending temperatures below normal across the area for the end of the week. The pressure gradient on the southern side of the high should remain strong enough for breezy conditions to continue on Thursday, with NE winds of 10-15 mph and gusts to 20 mph expected.
During the late week period, highs should range from the upper 60s to the low-to-mid 70s with nighttime temperatures at least falling into the 40s across the area. Thursday night has the greatest potential for peak radiational cooling as winds will start to relax and skies remain clear. With this forecast issuance, the typical cooler spots in southern IN and the Bluegrass region of KY would be expected to at least fall into the upper 30s, with a few mid 30s possible in the coldest valleys. Increasing cloud cover should keep temperatures slightly milder Friday night, but widespread 40s would once again be expected.
Next Weekend and Early Next Week...
An upper level low pressure system will evolve into a closed low over the Great Lakes region Friday into Friday night, gradually sinking into the upper Ohio Valley and middle Appalachians over the weekend. At the same time, upper level ridging will gradually shift eastward from the southern Plains into the lower and mid-Mississippi Valley by early next week. At the surface, a weak low pressure system supported by the aforementioned closed low aloft will slide across the Great Lakes Friday night into Saturday, with a weak cold front dropping across the Ohio Valley during this time period.
While there should be weak moisture return ahead of this system, PW values should remain below 1", and the combination of lacking moisture and weak forcing will likely keep us dry through the weekend. Temperatures will gradually increase through the period as heights begin to increase. Highs are expected to be in the 70s with low temperatures in the 40s and low 50s.
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.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/... Issued at 103 AM EDT Wed Oct 8 2025
With the cold front pushing through the area this morning, we will continue to see restrictions to flight cats for a few more hours. MVFR and IFR cigs will gradually ease over the coming hours, first at SDF, then later for LEX and BWG. NW winds behind the front are around 10kts, so fog potential with vis impacts will be rather low. We`ll see improvements to VFR later this morning for all terminals, with breezy winds becoming more NE by the afternoon. SKC and VFR is expected by tonight.
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.LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None.
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UPDATE...BTN SHORT TERM...CSG LONG TERM...CSG AVIATION...CJP
NWS LMK Office Area Forecast Discussion