textproduct: Louisville

KEY MESSAGES

* Dry weather is likely to continue today (~90% confidence) though clouds will increase overnight into Thursday morning.

* Clouds thicken for the morning commute though rain chances though confidence is low for morning rain showers. (90% of remaining below 0.1" in rainfall).

* Marginal severe storm threat for gusty winds Thursday afternoon, though confidence is low for storms on account of prolonged cloud cover and strong SE ridging.

* A stronger cold front will bring a chance for showers and storms again on Saturday. Another low-end threat for strong storms exists with this system.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 306 PM EDT Wed Apr 15 2026

===== Wednesday - Thursday =====

We are well above-normal today as highs soar into the mid to upper 80s in a few places. A few record highs could be broken with strong SW flow this afternoon. Otherwise, some high level cirrus clouds will stick around as a major trough remains to our north and west, along with most, if not all the rain this afternoon as well. There is plenty of surface instability and all that is needed is a trigger to initiate lift. Though a very small chance (<10%), an isolated storm is possible in our far northern IN counties, though most likely everyone remains dry and baking into the 80s.

With a jet overhead, SW winds will increase some today, with gusts of 20-30 MPH this afternoon. Eventually, clouds increase and lower with height tonight allowing the surface to decouple from these higher winds above. Overnight, clouds continue to thicken and rain chances increase from west to east sometime after 7 AM EDT. A shortwave from the west will approach our CWA though with weakening instability, frontogenesis, and shear, this line of showers and storms will fall apart as it closes in. How much this line weakens depends on how much a high over the SE US relents, with latest probability CAM guidance keeping high end rainfall totals under a tenth by noon tomorrow (>90%).

During the day and into the afternoon, clouds will stick around the whole CWA, acting as a lid to any convection that tries to initiate. Afternoon highs are a tad cooler in the mid to upper 70s from those clouds sticking around. The shortwave that moves through will keep a boundary draped over the central CWA. If this boundary can stall long enough with thinning clouds and increasing instability (increasing CAPE and dewpoints) from the SW in the afternoon and evening hours, convection could overwhelm the cap and initiate scattered showers and storms. A marginal risk for severe weather is possible for any afternoon storms with the main threat being gusty winds. Confidence is low in the severe threat given recent trends but is something we will monitor. The most limiting factor to storms or severe weather is the strength of the ridge at low to mid levels along with how much cloud cover can limit daytime heating. Still, some rainfall is likely, albeit small amounts with totals most likely remaining under 0.2" in (90%). A few places could see 0.5" in of rain if the SE ridge can weaken or move east slightly, forming more storms later in the evening (10%). SE high pressure keeps a warm SW flow for our area heading into the weekend.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 306 PM EDT Wed Apr 15 2026

===== Brief Dry Period on Friday =====

Mostly dry and warm weather is expected on Friday as upper ridging briefly moves across the region. This upper ridge will amplify in response to an upstream shortwave ejecting out of the Mountain West region. Southwest flow will persist and promote a WAA regime, which will allow temps to warm well into the 80s by the afternoon, and potentially challenge some max temp records. By Friday night, the upper ridge will begin to shift east, with a LLJ out ahead of an associated cold front beginning to enter into the area from the west. This will provide an increase in moisture transport overnight, and perhaps some rain chances mainly west of I-65 for Friday night.

===== Showers and Storms Saturday =====

The upper trough is expected to amplify across the central US on Saturday, with a deepening low moving north of the Great Lakes and across southern Ontario. An extensive cold front will trail southward through the Midwest, which will be the focus for showers and storms to sweep through the Ohio Valley. Ahead of the front, southwest gradient winds will be gusting to 20-30 mph, along with increasing cloud cover and approaching showers and storms. While it will be quite warm with temps reaching the upper 70s and low 80s, the cloud cover should somewhat limit heating, especially west of I- 65 where cloud cover will overspread the region earlier in the day. The warmest temps in the area will likely occur near the I-75 corridor due to a longer exposure to WAA and sunshine before the front and precip approaches.

SPC maintains the 15% risk for Saturday mainly for I-64 and north, including the Louisville and Lexington metros. However, there remains some uncertainty in regards to severe storm potential, primarily due to questions revolving around how much instability we'll be able to realize. The GEFS and GEPS ensembles indicate a 60- 70% chance of exceeding 500 J/kg of SBCAPE, a 40-50% chance of exceeding 750 J/kg, and a 25-30% chance of exceeding 1000 J/kg. High end amounts (10% chance of exceedance) top out around 1200-1300 J/kg. There is more confidence on shear parameters given the LLJ overhead, and expect to see deep layer shear values 40-50kts, sufficient for well-organized storms. Shear profiles are mostly unidirectional, which will support linear convection with a damaging wind threat. Regardless, the frontal boundary will provide strong forcing in a favorable shear environment with at least some marginal instability expected, so confidence continues to increase on shower and storm potential.

As of now, the highest chances for showers and storms will be from late morning through the entire afternoon ahead of the cold front. If the front is slower than expected, the severe risk could be greater given more time for diurnal heating to help destabilize our environment more. If it arrives quicker than expected, it will shut off our severe potential earlier in the day, leading to a potentially drier afternoon and evening. Confidence remains limited on FROPA timing, and may not gain much confidence until we get within the CAMs range.

Regardless of when exactly the front will pass through, our sfc winds will veer from the warm SW flow to a cooler and drier WNW direction, especially by the late evening hours. CAA will take over, leading to temps to drop into the 40s overnight.

===== Seasonably Cool Sunday into Next Week =====

In a post-fronal regime by Sunday, expect seasonably cool temps and drier weather. This will likely continue into Monday as well due to sfc high pressure building across the region. Highs on Sunday and Monday are expected to remain in the 60s. Monday morning could be an opportunity for some frost development, especially in the Bluegrass region as morning lows dip into the 30s. The 100-member LREF suggests a 40-50% chance of favorable frost conditions. Sfc high pressure will shift east of the area on Tuesday, leading to a return to the 70s for Tuesday and Wednesday.

AVIATION /18Z TAFS THROUGH 00Z FRIDAY/

Issued at 141 PM EDT Wed Apr 15 2026

VFR conditions today with high level clouds near 25 kft lingering into the overnight. Some SCT mid level clouds are passing through but these are expected to come and go throughout the evening. SW to S flow will dominate the whole period with current wind gusts of 20- 25 kts this afternoon before sunset. Gusts will die down overnight and clouds will thicken and lower by Thursday morning by 12Z. An approaching line of showers and storms will be moving in from the west but will quickly weaken and begin to dissipate as they approach our northwestern airports (HNB and SDF). Near and shortly after 15Z, a few isolated showers are possible that could drop ceilings to 3,500ft temporarily before quickly dissipating in the morning. Otherwise, everyone remains dry with OVC clouds Thursday morning with VFR conditions through the early afternoon.

LMK WATCHES/WARNINGS/ADVISORIES

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