textproduct: Louisville

KEY MESSAGES

* Waves of rain showers, with a few embedded storms, are expected today through Saturday morning. Severe weather and flooding remain unlikely with this system.

* The late weekend and into early next week will see drier conditions, before another chance for rain arrives by next Tuesday. Temperatures turn cooler by Thanksgiving Day.

UPDATE

Issued at 439 AM EST Fri Nov 21 2025

Over the past hour, there have been a couple ASOS/AWOS obs of 1/2 SM or less across southern KY, with KY Mesonet and traffic cameras also showing very low visibility across southern KY. Given the proximity to the developing warm front, think that these lower visibilities may persist for a while. A dense fog advisory has been issued until 9 AM CST to account for these reductions in visibility.

SHORT TERM /THROUGH TONIGHT/

Issued at 333 AM EST Fri Nov 21 2025

This morning, a renewed push of low clouds and moisture is working into the area from the southwest. Pockets of drizzle and fog have been observed across southern KY as low-level moisture settles in the presence of weak boundary-layer winds. Even though pockets of drizzle and persistent near-sfc saturation have kept things wet across the area last night into this morning, most of the actual rain shower activity has stayed south and west of the area through 08Z. A notable north-south gradient in temperatures is observed in latest obs, ranging from the upper 40s north of I-64 to the mid-to- upper 50s along the TN border.

As we head through the rest of the morning hours, an upper-level shortwave over the southern Plains will eject to the northeast across KS before moving to the east along the I-70 corridor this afternoon and evening. Mid-level frontogenesis over the lower Missouri Valley should support the development of a band of rain showers which will extend to the ESE across the lower Ohio Valley. This band of rain showers should move from SW to NE across the area later today, with rainfall rates generally being light, with a few embedded pockets of moderate rain. At the sfc, a stationary front over TN this morning will lift to the north as a warm front, with the front expected to end up near the I-64 corridor by this evening. To the north of the warm front, low clouds and showers will continue, with temperatures remaining fairly steady in the upper 40s and low-to-mid 50s. South of the warm front, warm advection via southerly winds should allow temperatures to warm into the 60s this afternoon, with showers becoming much more isolated.

By this evening, the shortwave energy and its associated sfc low will turn more to the east as it gets picked up by a departing northern stream trough. With the sfc low expected to track across southern IN and northern KY tonight, a trailing cold front will move across the southern half of the CWA during the late evening and overnight hours. While the warm sector with this system will not be particularly robust, sfc dewpoints climbing into the low 60s this evening should allow for around 500 J/kg of SBCAPE across southern KY, with similar amounts of MUCAPE located further north. With the combination of modest instability within the warm sector and forcing along the cold front, think that a line of showers and storms will move across the region late this evening into early Saturday morning. While deep-layer shear is sufficient for organized convection, lacking instability and fairly unidirectional shear profiles should limit the overall severe threat. However, given the proximity to better instability across the TN valley, a strong storm can't be completely ruled out along and south of the Cumberland Parkway tonight (note the SPC Day 1 marginal risk).

Otherwise, a drying trend is expected from NW to SE behind the front after midnight tonight, though low clouds and patchy drizzle/mist will likely continue into early Saturday morning. NW winds will bring in weak cold advection behind the front, with lows ranging from the mid 40s (NW) to the mid 50s (SE) Saturday morning.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 333 AM EST Fri Nov 21 2025

Saturday through Sunday Night...

The upper level shortwave and its associated sfc low will cross the Appalachians into the mid-Atlantic on Saturday, with drier northerly flow working into the region in its wake. Low-level moisture will be a bit slow to clear, so while most areas should remain dry during the day on Saturday, a stratus layer may stick around through much of the day before clearing from north to south during the afternoon and evening hours. A spotty shower can't be ruled out south of the Parkways on Saturday where the low-level moisture will be a bit deeper. Highs on Saturday in most locations should warm into the upper 50s and low 60s, fairly seasonable for this time of year.

Depending on how much clearing occurs Saturday afternoon, there is a signal for areas of fog Sunday morning, especially south of I-64. Otherwise, Sunday should bring the dry weather and mostly sunny skies across the area as high pressure moves across the region. After a cool start in the 30s, temperatures should warm into the upper 50s and low-to-mid 60s Sunday afternoon. Mid- and high-level clouds will increase from the west Sunday night, with lows falling into the upper 30s and low 40s.

Monday through Thanksgiving...

High pressure over the region on Sunday will pass east of the Appalachians Sunday night into Monday morning as another low pressure system moves across the central Plains. South-southwest low- level flow will begin to lift moisture northward into the mid-MS and lower OH Valley during the day on Monday, increasing clouds and promoting warm advection which should lead to milder high temperatures Monday afternoon. There is still some timing differences in how fast rain arrives into KY/IN, with the faster GFS/GEM starting as early as Monday afternoon, while the slower ECMWF holds off until Monday night. Given that models tend to be too fast with moisture return, it would appear more likely that the daytime hours on Monday remain dry, with rain increasing from west to east Monday night.

The main push of rain showers is expected to cross the region late Monday night into Tuesday morning as the upper wave and its associated sfc low cuts across the mid-Mississippi Valley and into the Great Lakes. The system is expected to be weakening as it passes near our region, so it looks like the potential for strong storms will be low and overall rainfall amounts will be modest (0.50-1"). Medium-range guidance has trended toward keeping rain showers near the region into the first half of the day on Wednesday until the main upper trough axis begins to push through. As a result, would not be surprised if subsequent forecasts increase PoPs on Wednesday, especially east of I-65.

Wednesday into Wednesday night, west-northwest winds will bring stronger cold advection into the region, leading to a progressive step down in temperatures as we head into Thanksgiving. While temperatures on Wednesday should be near normal, below normal temperatures are likely on Thanksgiving Day, with lows in the 20s and low 30s and highs in the low-to-mid 40s. Model guidance is fairly consistent in showing high pressure moving across the region on Thanksgiving, so dry weather would also be expected at this time.

AVIATION /12Z TAFS THROUGH 18Z SATURDAY/

Issued at 649 AM EST Fri Nov 21 2025

Low clouds, rain showers, and patchy fog and mist are expected to move across the region today as a warm front lifts through the area. Still expecting that the lowest flight categories will be on the north side of the warm front, which should be over BWG this morning before lifting toward a HNB-LEX line by this afternoon and evening. While cigs and vis have bounced over the past few hours, would expect conditions to settle into IFR/LIFR for most of the morning and early afternoon hours. Some improvement is likely at BWG and RGA this afternoon, and coverage of showers should also diminish across southern forecast sites.

Through the day today, winds will generally be light out of the E/SE, veering to the south and southwest tonight as the sfc low moves across the region. A final band of showers, potentially with embedded thunderstorms, should move across the region between 04- 09Z. Ceilings are likely to settle into IFR/LIFR ranges again tonight before gradual improvement on Saturday. Overall, this is a low-medium confidence forecast.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Dense Fog Advisory until 9 AM CST this morning for KYZ026-027- 061>064-070>078-081-082. IN...None.