textproduct: Louisville

KEY MESSAGES

* A Dense Fog Advisory is in effect for visibilities as low as 1/4 mile this morning.

* Otherwise, dry and warm weather will return today and Tuesday, with rain chances returning by Wednesday and Thursday, along with the chance of some rumbles of thunder.

* Long range trends suggest lows in the 30s and 40s by the weekend.

DISCUSSION

Issued at 340 AM EDT Mon Oct 12 2026

===== Foggy Morning Now But Heat Returns Today =====

We can finally say that the remnants of Isaias are getting kicked out to the east coast. Unfortunately, left over residual moisture at the surface combined with clear skies overhead have allowed widespread dense fog to form, at least throughout central, eastern and southern KY. A Dense Fog Advisory has been issued for most of our KY counties as a result and may be expanded for the morning rush hour. Visibilities have dropped to 1/4 mile in places, with less prevalent fog in Indiana. Even here though, the usual valley locations near creeks and streams have formed thick fog. Regardless, allow extra time to go to work today and increase the following distance. This is probably said too much but never let your guard down driving foggy roadways.

Good news is that mostly clear to partly cloudy skies are expected today. A very weak mid-high level disturbance will drift high to mid level clouds in the late morning and afternoon hours from west to east. As they drift, they'll allow western areas to receive more peak heating from direct sunlight in the afternoon with highs reaching the upper 80s with low 80s in the east due to the timing of the passing clouds. There is a low-end chance (<20%) of some western communities to reach 90 degrees today. Those that don't see 90 today will have a higher chance tomorrow. Before then, SW flow will remain as ridging builds in today and Tuesday with lows Tuesday morning in the low 60s. With good mixing today, fog probabilities are near zero or at least well below 20% Tuesday morning.

For Tuesday, highs are quick to jump into the mid to upper 80s across the entire CWA. SW flow may be a little stronger in western communities with some communities well west of I-65 having a 40-50% of reaching 90 Tuesday, which is quite warm for mid-October. Tuesday ends quietly like today will be with warm overnight lows in the low to upper 60s.

===== Rain Returns with Major Cool Down by the Weekend =====

As Wednesday arrives, a pattern shift will be ongoing. A battle of influence between a retreating high to our south and a slowly advancing trough trying to lift north at the same time arrives on Wednesday afternoon. Long range models are painting a picture of the advancing trough slowly pushing east being slowed down. A NE oriented jet streak on the east side of the trough encourages the trough to lift north over the northern Ohio Valley. However, this jet streak may be close enough for our CWA to receive repeated waves of rain from decaying MCVs and moisture streaming from the Pacific and Gulf. At this time, it's difficult to determine which passing disturbance will deposit the most rain. However, latest LREF guidance shows PWATs exceeding the 99th percentile of climatology near 2.00" in our Indiana counties and slightly south of the Ohio. With how warm we will be in the mid to upper 80s, any rain that approaches brings the threat of storms. However, the best shear will remain too far north as the jet streak seems pointed towards the Great Lakes. Additionally, instability seems to be rather weak though enough will be around for at least some rumbles of thunder.

As this trough slowly trudges east, energy will be transferred to a developing low somewhere near the Great Lakes, possibly aided with extra lift from the left exit region of the aforementioned jet streak. High temperatures are generally slow to cool as the trough will take a while to clear. The exception to this would be quick- timed rain-cooled afternoons from passing MCVs. The trough should clear by Friday as a mostly dry cold front passes through.

With all that said, rainfall totals this week are right-skewed with the highest totals from LREF ranging 1-3". The consensus is near 0.5- 1", though I'd imagine localized areas of 1-3" are possible should convection come and go for a couple days. There is a strong signal of a sharp cool down by the weekend. Frost may be possible as low temperatures plunge well into the 30s by Sunday morning.

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/

Issued at 648 AM EDT Mon Oct 12 2026

Widespread fog is still affecting BWG-LEX-RGA with visibilities as low as 1/4SM at times. This will continue for the next few hours through 15Z or hopefully earlier until fog mixes away west to east. HNB-SDF have not fogged as severely now and should avoid thick fog for the rest of the day though it is still possible to have a quick ob of IFR fog with reduced visibilities below a mile. Otherwise, passing SCT-BKN clouds at high levels will pass through with SW winds of 6-10kts are expected Monday afternoon. Winds will lessen overnight into Tuesday in a continued SW to southerly flow. VFR conditions expected to end Monday heading into Tuesday morning.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning for KYZ023>043-045>049-053>057-061>067-070>078-081-082. IN...Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning for INZ076>079-084-089>092.