textproduct: Louisville

KEY MESSAGES

* Cool/dry weather is expected tonight and Monday. Patchy frost will be possible early Monday morning across southeast Indiana and into the Bluegrass region of central Kentucky.

* A warming trend will begin Tuesday and continue through the rest of the week.

* A slight chance of rain is possible across the northern Bluegrass Wednesday. The next chance for appreciable rainfall will be Friday into Saturday.

SHORT TERM /THROUGH MONDAY/

Issued at 307 PM EDT Sun Apr 19 2026

===== Today - Monday Evening =====

For the rest of the afternoon heading into this evening, gusty winds of 20-30 MPH will continue due to some decent mixing in the lower levels. Very dry air is in place from this Canadian air mass overhead being a stark contrast to the warm and mild weather we've had recently. After sunset, gusty winds will die down, and clouds become overcast overnight. An approaching cold front will shift winds out of the north riding along the general troughing pattern over the Great Lakes. This front is dry but will impact how much frost develops early in the morning. Latest guidance stalls the clouds a little longer to about an hour or two before sunset, meaning patchy frost is possible (30-50%) in our northern counties. As a result, frost advisories have been issued for any sensitive vegetation in these counties though if recent trends hold, only patchy frost is possible, especially if cloud cover can linger through sunrise. Morning lows are coldest in the north ranging in the mid 30s to low 40s in southern areas.

Despite the morning clouds, Monday will be a pleasantly sunny day with calm winds and cooler air being drawn in from the NNE. Highs will still be somewhat mild in the low to upper 60s area wide with calm winds as a ridge of high pressure builds in from our west. Conditions begin to change later Monday night as the ridge keeping us cool will shift surface winds out of the SW beginning a dry warm trend Tuesday morning.

LONG TERM /MONDAY NIGHT THROUGH SUNDAY/

Issued at 307 PM EDT Sun Apr 19 2026

Monday Night through Wednesday Night...

NW flow aloft will be in place over the Ohio Valley Monday night. An upper level trough is forecast move off the East Coast, while a deep upper low rotates toward the West Coast. In between, upper level ridging is forecast to amplify over the Rockies. A separate upper level trough and weakening sfc are forecast to move east near Hudson Bay. A broad sfc high pressure system will shift southeast over the eastern US.

Low-level winds will veer S/SW Monday night into Tuesday, advecting warmer air into the region on the NW side of the high. While sfc winds begin to veer southerly Monday night, winds will be quite light. Clear skies will promote radiational cooling, with a steeping inversion setting up beneath WAA off the surface. Lows Monday night will range from the mid/upper 30s in the Bluegrass Region to the low to mid 40s along and west of I-65. Could certainly see some frost development, mainly limited to river valleys and low-lying areas in the Bluegrass.

Breezy SW flow will continue to advect warmer air into the region on Tuesday. Mostly sunny conditions will allow temperatures to rise into the mid/upper 70s in the afternoon. Upper level ridging will build eastward across the central CONUS through midweek. We'll just have a subtle mid-level disturbance on the northeast side of the ridge sliding southeast over the Ohio Valley Tuesday night. A weak sfc cold front is forecast to sink south of the Great Lakes Tuesday night into Wednesday, likely stalling north of the Ohio River. Moisture will be limited, but there is a small chance (20-30%) for brief light rain in southern IN and northern KY. Along and south of I-64, the vast majority of LREF members are dry until Friday. Even north of I-64, total rainfall amounts through Wednesday will be less than 0.10".

Thursday through Saturday...

The upper level ridge builds east over the Ohio Valley for Thursday, with warm SW flow continuing in the lower levels. A strengthening low pressure system is forecast to move northeast over the northern Plains. We'll stay dry and quite warm, with afternoon highs in the low to mid 80s.

Heading into Friday, medium range guidance suggests the deep area of low pressure will occlude over southern Canada, with additional upper level energy phasing with the parent upper low. This system should send a cold front east through the area Friday into Friday night. We may finally get some deep moisture along this boundary with LREF mean PW values around 1.25 inches (exceeding the climatological 90th percentile). Appreciable rainfall appears possible, but the risk for heavy/excessive rainfall and severe weather looks to remain low.

Ongoing moderate to severe drought conditions in central KY are likely to worsen this week, given the mainly dry forecast until Friday. Observed rainfall amounts on Saturday were mostly between 0.10-0.30 inches, which won't significantly alleviate the current drought.

AVIATION /00Z TAFS THROUGH 06Z TUESDAY/

Issued at 743 PM EDT Sun Apr 19 2026

VFR conditions will persist through the TAF period. Any ongoing gusts across the terminals will end within the next hour or two, with relatively calm winds following. Winds will be initially from the west, shifting and remaining to the north as a weak cold front passes through early Monday morning.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Frost Advisory from 4 AM to 9 AM EDT Monday for KYZ031>033-036- 037-042-043. IN...Frost Advisory from 4 AM to 9 AM EDT Monday for INZ076>079-092.