textproduct: Louisville

KEY MESSAGES

* Light showers and a few elevated storms will move northwest to southeast across the area this morning. Gusty southwest winds expected today, with temperatures returning to the upper 70s and near 80.

* Additional gusty showers and storms expected Tuesday, especially Tuesday night, as a cold front sweeps through the region. Rainfall amounts between 1-2 inches expected, which will be beneficial given the ongoing drought conditions across Kentucky.

SHORT TERM /THROUGH TONIGHT/

Issued at 352 AM EDT Mon May 4 2026

Regional radar this morning shows several clusters of showers and storms moving across MO/IL southeastward into IN/KY. This early morning activity is being driven by DPVA underneath the entrance region of a compact upper level jet, along with a 45kt LLJ that is producing a strong WAA wing extending from St. Louis to Louisville. Storm motion is primarily driven by the 700mb jet, which is oriented NW to SE from northeast Missouri into central KY. Upstream convection developing across IL will follow this jet orientation, and we'll see an increase in shower and storm activity this morning as these storms work downstream and into our area. Shear parameters are increasing this morning, though a stout low level inversion will keep any lingering instability aloft, resulting in any storms to be elevated.

Sfc obs do show rather dry airmass in place, with dewpoint depression around 15-20 degrees this morning. ACARs soundings add confidence to the extent of this dry layer, which shows a deep dry layer up to 700mb this morning. Additionally, a thunderstorm moved across Meade county earlier in the night, and the KY Mesonet only recorded 0.04" of precip. So dry air is certainly impacting the amount of precip reaching the sfc, but as we see more activity approach the area, top-down saturation will lead to a more favorable environment for more measurable precip. Best precip chances through this morning are across southern IN and majority of central KY, with our south-central KY counties expected to remain dry.

The LLJ core is expected to slide just north of the area later today, which will also push the better moisture transport axis to the north. The band of precip will likely lift north of I-64 later this morning or early afternoon, resulting in a drier trend through the rest of the afternoon and evening for the entire area. Low level lapse rates will steepen through the afternoon, allowing for more mixing and gusty winds up to 30mph as a result. SW wind gusts will continue to promote the WAA regime, and will see temps climb back into the upper 70s and low 80s because of it.

By tonight, precip chances will begin to shift back to the south and across the I-64 corridor as moisture transport increases again ahead of a cold front. Strong WAA will keep us very mild overnight, with lows only dropping into the 50s.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 352 AM EDT Mon May 4 2026

===== Tuesday through Wednesday Night ======

The upper level pattern will feature a deep upper low over Ontario on Tuesday, which will present general troughing across the eastern US. An extensive cold front will be stretching from the Great Lakes through the Midwest and down into the southern Plains. As this front approached the area on Tuesday, the LLJ will strengthen, resulting in a considerable increase in moisture transport ahead of the front. Precip coverage will increase throughout the day, leading to relatively high chances for the morning and afternoon.

By Tuesday evening and into the overnight, the LLJ will continue to strengthen across the lower OH/TN valley, possibly exceeding 45kts in the 850mb layer. This will maximize our moisture transport vector just ahead of the front, supporting a line of gusty scattered to numerous showers and storms to push from west to east through the area overnight. Model soundings suggest little to no instability to be present, though quite impressive shear parameters due to the LLJ core directly overhead. There should be a healthy inversion to keep any storms elevated, which would be good given the 0-3km curvature in the hodographs. There is high confidence on seeing overnight precip activity, so have increased PoPs to 100%.

In addition to the high confidence precip, the moisture transport will increase our PWATs to over 1.3", with roughly a 60-90% chance of exceeding 1.4" (90th percentile of BNA sounding climo) across central KY. We can expect a broad 1-2 inches of QPF across the region with the cold front passage. NBM 90th percentile comes in around 2-2.5" of rainfall, which could be possible in isolated locations due to any localized heavier downpours. This QPF will be a welcome sight given the ongoing drought conditions across the area. Majority of Kentucky is experiencing at least moderate (D1) drought, though just about all of the southern half of the Commonwealth is in severe (D2) and extreme (D3) drought.

The cold front will pass through the forecast area early Wednesday morning, first entering our southern IN counties by 06z, then pushing east of I-65 before 09z. The front will be east of almost the entire area 12z Wednesday, but looks to get slightly hung up across the Lake Cumberland area for several hours before eventually clearing the southeast by the afternoon. This will make forecast highs a bit tricky in our southeast, but generally expect highs to be in the 60s. Rain chances will linger behind the front too, especially east of I-65 through most of Wednesday. By Wednesday night, should begin to see a gradual drier trend for areas west of I- 65.

===== Thursday - Next Weekend =====

We remain under general upper level trough through the end of the week, with additional weak shortwaves pinwheeling around the upper low and providing additional precip chances into the weekend. Best chance for a dry day during this period will be Friday as sfc high pressure moves across the southeastern US. Otherwise, daily isolated to scattered precip chances continue Thursday, Saturday, and Sunday. Temperatures are expected to return to near normal by the weekend with highs in the 70s.

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/

Issued at 647 AM EDT Mon May 4 2026

Scattered showers and storms are moving across the region this morning. VFR cigs will remain today, with some partial clearing later this afternoon. Morning precip activity will lift back north of the area by early afternoon, leading to a drier period for the afternoon. SW winds will be gusty today, with gusts up to 25kts possible. Low chance for isolated shower tonight at SDF and HNB, so included PROB30 groups tonight.

LMK WATCHES/WARNINGS/ADVISORIES

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