textproduct: Louisville

KEY MESSAGES

* Intermittent chances for light rain continue over the next few days as a weak frontal boundary meanders over the area. Rainfall amounts less than a quarter of an inch expected between today and tomorrow.

* Unseasonably warm temperatures are likely through Sunday, with temperatures expected to be 15-20 degrees above normal.

* A strong cold front is expected to move through the region Sunday into Sunday night. A line of showers and some storms is expected ahead of the front. There is a chance for some storms to become strong to severe.

* Temperatures plummet into the 20s by Monday morning and lasts through mid next week.

UPDATE

Issued at 859 PM EST Wed Dec 24 2025

Upper sky cover is pushing southeast of the region at this hour, which is helping temperatures to fall and fog to develop. The western third of the region is seeing some patchy dense fog in some locations. Therefore, an SPS has been issued for the next several hours. Low stratus is expected to build back over the region tonight, which could prohibit further fog development. Will continue to monitor observations and area cameras. Another SPS may be needed or possibly an upgrade to a Dense Fog Advisory.

The remainder of the previous forecast remains on track for this Christmas Eve. Santa will have an easy ride through the region tonight, but will just have to watch out for some low level clouds and fog.

SHORT TERM /THROUGH FRIDAY/

Issued at 240 PM EST Wed Dec 24 2025

Depending on where you are located in KY determines if you're having a bright and sunny or grey and overcast Christmas Eve. Low stratus is covering a good chunk of the area today, with clouds just a few hundred feet off the ground. However, there is a sharp cut off of the cloud deck, and portions of north-central and eastern KY have plentiful sunshine today. We can thank a pesky sfc boundary that is situated across the area today for the cloud cover. Temps range quite a bit across the forecast area, from mid-50s to upper 60s. Despite the cloud cover across south-central KY, better WAA is down that way which has helped them warm to nearly 70 this afternoon.

===== Increasing Rain Chances Tonight =====

Sfc high pressure across the Great Lakes this afternoon has helped suppress the sfc boundary to near the KY/TN border. By tonight, that sfc high will shift over the mid-Atlantic, which will allow the sfc boundary to meander northward as a warm front. When doing so, a weak mid-level shortwave embedded in NW flow will pass through, supporting a weak LLJ response overnight. We'll see an increase in moisture advection for the region, but the best transport magnitude could be across northern KY, southern IN, and southwest OH. Combined with this increase in moisture, isentropic lift over the warm front will support scattered shower activity tonight, with the better chances for rain focused mainly in our northeastern third of the forecast area, from roughly Salem, IN to Berea, KY.

Model soundings for tonight suggest a small layer of elevated instability above a sharp nocturnal inversion and mainly between 900- 700 mb. Hi-res models indicate we could have a few instances of some thunder, which seems reasonable given the weak elevated instability in the soundings. Otherwise, rainfall amounts are generally expected to be light, with a few hundredths possible.

Temperatures will remain nearly steady through tonight due to increasing SW flow as the front lifts north. Temps in the 50s for most overnight

===== Warm Christmas Day =====

By tomorrow morning, the sfc boundary is expected to be along or just north of the Ohio River. We could see some lingering light rain or drizzle across the Bluegrass region, but not expecting a washout. Slightly drier air is expected later tomorrow, which will help lower our PoPs some for tomorrow. We'll still carry some low-end chances, as we could have some very isolated to scattered light rain, per the hi-res guidance, but still expecting very light QPF if any.

The bigger story for tomorrow should be how warm it will be. Strong WAA pattern will remain in place, which will allow our sfc temps to warm well into the 60s across the entire area. While we are not expected to break the Christmas Day max temp records, which were last broken in 2021, we certainly are looking at a Top 10, if not a Top 5, warmest Christmas on record.

Sfc high pressure moving across Ontario, Canada will extend south into the Great Lakes tomorrow too, which will help push that sfc boundary back south. It should end up close to the KY/TN border, again, by tomorrow evening.

===== Friday Forecast =====

Friday starts out quite similar to Christmas morning, with most folks in the 50s, but some low 60s in our south will be possible. Warm min records are slightly lower than surrounding days, so this Friday could end up challenging some of those warm min records.

Another mid-level shortwave will pass over the Ohio Valley during the day, which will support a sfc low to track along the I-70 corridor from Missouri to Ohio. A LLJ will strengthen over IN/OH by the afternoon, which will bring another wave of strong moisture advection into the region. The front across our area will likely get pulled a bit to the north again, with isentropic lift once again providing better PoPs mainly in our northeast.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 240 PM EST Wed Dec 24 2025

Friday Night through Saturday...

Upper ridging will remain over the southern CONUS and begin to shift northeastward Friday night. On Saturday, this ridging, and quiet upper flow will keep conditions dry and warm. Expecting to see warm temperatures on Saturday, with highs in the mid-to-upper 60s and southern KY in the low 70s.

Saturday Night through Mid Next Week...

Saturday night, the trough over the Pacific Coast will finally push east across the CONUS and into the Ohio Valley by Sunday night. On Sunday, ridging will begin to push east of the region, and vorticity shedding from the approaching troughing will move over the lower Ohio Valley. Warm temperatures, present moisture, and this little lift will be enough to support scattered showers on Sunday. The quickly matured low pressure system will strengthen as it pushes over the Ohio Valley. The cold front of this system will move southeast through the region on Sunday evening/night. The low-level convergence along the front, the strong LLJ, and strong troughing will bring plenty of lift to present moisture. Will expect to see a line of showers and storms along the cold front. Taking a look at ensembles and cluster analysis, there is good agreement on stronger troughing moving through during this time frame, so forecast confidence has increased. This would also bring some instability into the region, making it a high shear and low CAPE environment. There is about a 40-50% chance of seeing 60F or higher dew points as this system moves through. Not expecting widespread severe weather, though some storms may become strong to severe. Will continue to monitor this system over the next several forecast periods.

Behind the cold front, strong CAA will allow temperatures to fall Sunday night into Monday to below normal values. As precip exits the region, some rain/snow mix or all snow may remain for a few hours early Monday morning. Not expecting much accumulation, if any. Highs Monday through Wednesday look to be in the 30s and lows Tuesday and Wednesday morning in the upper teens and low 20s. Wind chills Monday through Wednesday morning will be in the low teens. Though chilly, conditions will remain dry under this synoptic set up.

AVIATION /06Z TAFS THROUGH 12Z FRIDAY/

Issued at 102 AM EST Thu Dec 25 2025

Very complex fog and low cloud forecast, so forecast confidence is a bit lower than usual even in the near term. Ceilings are mostly VFR to begin this TAF period, but some patchy fog is causing some issues at a couple terminals, including SDF. However, widespread low stratus currently just north of the region is expected to overspread the area once again from north to south between 08-12Z. The lowest ceilings, including widespread IFR/LIFR, are expected after 12Z as a weak frontal boundary to the north sags back south over southern IN and north-central KY. However, there is a bit more uncertainty if the IFR will make it as far south as BWG later today.

Winds will increase to 5-10 kt out of the SW this morning, with winds veering N/NE at the northern terminals this afternoon in the wake of the front.

LMK WATCHES/WARNINGS/ADVISORIES

KY...None. IN...None.