


Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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996 FXUS63 KLMK 181723 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 123 PM EDT Sat Oct 18 2025 ...Updated Aviation Discussion... .KEY MESSAGES... * Warm and windy conditions are expected today. Wind gusts of 20 to 25 mph are likely, with high temperatures approaching daily records. * A strong cold front will move through the region late tonight . into tomorrow morning. A strongly forced line of showers and thunderstorms is expected. Some storms could be strong to severe with damaging winds being the primary hazard. However, a spin-up tornado can not be ruled out in areas west of I-65. * Cold front will slice through the region Sunday morning, with showers lingering through the day. Gusty winds are expected through the day with gusts of 30 to 40 mph. * Drier and much cooler weather is expected for much of next week, with a small shower chance Monday night. Frost will be possible Wednesday and Thursday mornings, especially in the Bluegrass region. && .UPDATE... Issued at 1040 AM EDT Sat Oct 18 2025 Morning satellite imagery reveals mostly sunny skies across southern Kentucky with partly cloudy skies across much of western Kentucky and southern Indiana. Weak isentropic lift has resulted in a few light showers across southwest and west-central Indiana this morning. Some of the CAMs were picking up on this. This activity should continue to move to the northeast through the morning. However, will do a quick update to add some slight chance PoPs across portions of Dubois/Orange/Washington counties of southern Indiana for a few hours. Remainder of the forecast here looks pretty good for the afternoon with breezy conditions (wind gusts 20- 25 mph) and highs in the 83-88 degree range. Wanted also to touch on the potential for a period of gusty winds overnight. For the past several days we`ve been highlighting the risk of strong storms moving into the region from the west tonight that could produce some damaging winds in spots, especially where stronger cores are present. However, it is looking more likely that we`ll see a period of gusty winds just ahead of the showers/storms as they move in late tonight. 06Z and 12Z HRRR solutions continue to show the low-level jet ramping up after sunset with a pretty good core of higher momentum air setting up just off the deck. Model soundings show an inverted V profile indicative of drier air in the low-levels just ahead of the advancing convective line. As precipitation starts to fall through this dry layer, we may be able to mix down some of that higher momentum air and a period of gusty winds (45-50 mph) could occur in advance of the rain. Once the rain starts over a location and saturates the profile downward, the momentum transfer will be much more muted. I`ve seen in this several times in the past couple of years here where we had a period of very gusty winds just on the front side of an advancing line of showers/storms. We`re going to continue to look through the remainder of the 12Z high resolution datasets, but I suspect that we may hoist a Wind Advisory late tonight across portions of the region to address this period of potentially high wind gusts. Once this well advertised front pushes through Sunday morning, we`ll see a lull in the winds during the morning hours, but another round of gusty winds will be possible in the afternoon. Although, much of the guidance has trended downward on wind gusts for Sunday afternoon due to an increase in cloud cover which may limit downward momentum transfer due to more muted mixing. && .SHORT TERM /THROUGH SUNDAY/... Issued at 401 AM EDT Sat Oct 18 2025 Early this morning, a subtle upper-level shortwave is moving across the Ohio Valley within broader SW flow. This wave has brought scattered to broken mid- and high-level clouds over the past 12-18 hours, with the back edge of these clouds expected to clear the area by mid-morning. Temperatures are currently exhibiting a pronounced ridge-valley split, as more exposed locations currently have a light S/SE breeze keeping temperatures milder while valley locations are still able to decouple. Current readings as of 07Z range from around 50s in the coolest locations to the low-to-mid 60s in the warmest areas. Temperatures should remain fairly steady between now and sunrise. Today, warm and breezy conditions are expected across central KY and southern IN as deep SW flow settles in between a departing upper ridge and an approaching upper trough. H85 flow of around 20-30 kt through the day will allow for some stronger wind gusts to make it to the sfc. Fortunately, the area which is expected to see less cloud cover and deeper mixing will also have slightly weaker flow aloft, and vice versa, so most locations should see peak wind gusts in the 20-25 mph range, with a few 30 mph gusts. Low-level veering of winds will support strong WAA, with the only limit on heating today being increasing cloud cover from the NW this afternoon. Near- record high temperatures are expected this afternoon, particularly at BWG, with many areas south of the WK/BG Parkways warming into the mid-to-upper 80s. Areas farther north and west should top out in the low-to-mid 80s. Over the next 18-24 hours, an initially complex area of broad upper troughing over the north central CONUS will consolidate into a highly-amplified wave as shortwaves ejecting out of the Rockies and southern Plains this morning merge into a single wave by the time it reaches the Miss. Valley Sunday morning. While there should be enough of a mid-level cap to keep most of the area dry through the daytime hours today, height falls to the immediate NW of the region may be sufficient for a few storms to sink into our southern IN counties during the late afternoon and early evening hours, as depicted in several of the 00Z hi-res models. This time period would have the best instability, with HREF mean SBCAPE between 500-1000 J/kg and max SBCAPE approaching 1500 J/kg. While wind shear won`t be as strong as overnight tonight, 35-40 kt of deep-layer shear should keep storms organized, though soundings suggest most of that should be speed shear. The more widespread threat for showers and thunderstorms is expected late tonight into Sunday morning as the cold front and the main upper trough axis swings across the region. A 100+ kt H5 jet will descend across the MO River basin late tonight, with strong upper diffluence expected ahead of the trough axis. Low-level response will lead to the development of a 55-60 kt LLJ across the Ohio Valley tonight, providing ample wind shear for convective organization, as well as bringing greater Gulf moisture up into the region. Immediately ahead of the front, PW values should surge to 1.6-1.7", exceeding the 95th percentile of climatology. While a corridor of low-to-mid 60s dewpoints will move across the region immediately ahead of the main convective line, instability is still expected to be limited, especially as you go east of the I-65 corridor. HREF mean CAPE progs are only around 100-300 J/kg, with maximum CAPE values only approaching 500 J/kg. In contrast, shear will be strong as mentioned above, and model hodographs do depict good low-level curvature, with 200-300 m2/s2 0-1 km SRH. Most hi-res models show a line of thunderstorms moving across the Miss. Valley this evening, reaching our western CWA border around or just after midnight. As this line moves from western KY and southern IL into central KY and southern IN, a gradual lessening of convective intensity is expected as storms encounter a more stable environment. The main forecast question is will convection still be strong enough as it crosses into our region to either get strong winds aloft down to the surface or to get quick spin-up tornadoes thanks to the strong low-level helicity. As it stands, the overall severe threat for tonight is low, but strong straight-line winds and a spin-up tornado are possible. While brief heavy rainfall rates are likely tonight into tomorrow morning, the progressive nature of this system and lack of robust convection should keep rain totals low enough to preclude flooding concerns. While basin average rainfall amounts of 0.50-1.25" are expected, HREF LPMM values indicate the potential for up to 1.5-2" in narrower swaths. Showers should continue along and immediately behind cold FROPA during the day on Sunday, with low-level lapse rates steepening behind the front. There is some potential for low-topped convection bringing strong wind gusts across the Bluegrass during the morning on Sunday, which is likely what has prompted the Day 2 marginal risk. Gradient winds will remain strong throughout the day on Sunday as strong CAA overspreads the area. There is more uncertainty now as to whether we will be able to get enough mixing to get advisory level wind gusts on Sunday, as models have trended toward more cloud cover and showers during the peak heating window. Still think that widespread 30-35 mph wind gusts are a good bet, with isolated 40+ mph gusts possible. Temperatures will likely be stuck in the 50s and low 60s through the day thanks to the aforementioned CAA and cloud cover. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 401 AM EDT Sat Oct 18 2025 By Sunday evening, the upper trough associated with the active weather over the weekend will already be ejecting to the northeast across the Appalachians as sfc high pressure builds into the Gulf states. Skies should continue to clear from west to east, and winds should gradually subside overnight as the pressure gradient weakens. With the cooler air mass now overhead, temperatures should easily fall into the upper 30s and low-to-mid 40s Monday morning. For the day on Monday, a progressive synoptic pattern will cause flat upper ridging and the sfc high pressure over the Gulf states to quickly slide to the east, with warmer return flow beginning across the area by Monday afternoon. As height falls occur to the NW of the region with another approaching trough, breezy SW winds should help send temperatures recover into the mid-to-upper 60s and low 70s Monday afternoon under mostly sunny skies. The upper trough should descend from the northern Plains toward the Ohio Valley Monday evening into Tuesday morning, bringing another sfc cold front through the region. The track and relatively un- amplified nature of the system will limit its ability to tap into Gulf moisture, and PW anomalies along and ahead the cold front are unimpressive. As a result, while a few showers will be possible as the cold front passes Tuesday morning, the more noteworthy sensible weather impacts will be the wind shift as gusty westerly winds are expected through the day on Tuesday. As the upper low pivots over the Great Lakes Tuesday night into Wednesday, it may be just close enough to our area to bring increased cloud cover across the northern CWA through Wednesday. Regardless, continued CAA Tuesday night into Wednesday should bring the coolest temperatures of the season thus far during the middle of the week, with highs in the low- to-mid 60s and lows in the upper 30s and low 40s. Sfc high pressure moving across the region Wednesday night into Thursday should bring the best radiational cooling conditions, and this period has the best chance of frost during the current outlook period. For the latter portion of next week, digging troughing off the Pacific coast should allow for ridging to build over North America, though there is some suggestion in medium-range guidance of split flow with a cutoff low meandering over the central Plains into the Mississippi Valley next Thursday into Friday. Temperatures are expected to moderate somewhat, though the magnitude of warming is uncertain given the potential for clouds/showers associated with the cutoff low. && .AVIATION /18Z TAFS THROUGH 00Z MONDAY/... Issued at 122 PM EDT Sat Oct 18 2025 VFR conditions are expected this afternoon with breezy south to southwest winds. Cu field is expected along with some mid-high level cloud cover. Wind gusts of 18-20kts will be possible through the afternoon with winds slacking off toward sunset. Could still see a stray shower at KHNB late this afternoon and evening, though most locations should remain dry through at least 19/04Z. Overnight, a strong cold front will push through the region. Ahead of the cold front, a low-level jet will overspread the region resulting in LLWS at all the terminals. Winds will be primarily from the south at 10-12kts with gusts to 25kts being possible. Showers and a few thunderstorms look to cross the terminals between 19/05-13Z. Some locally higher gusts to 35-40kts can`t be ruled out on the front edge of the line of showers and with embedded heavier storms. Cold front should clear KHNB by 19/10Z, KSDF/KBWG by 19/12Z and KLEX/KRGA by 19/13-14Z. Expect MVFR cigs behind the front with gusty west to west-northwest winds through the afternoon on Sunday. && .CLIMATE... Issued at 401 AM EDT Sat Oct 18 2025 Record High Temperatures Possible... Sat, Oct 18th Rec (Yr) | FCST SDF 87 (2016) | 84 LEX 87 (1938) | 83 BWG 88 (2016) | 88 FFT 88 (1938) | 84 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE.......MJ SHORT TERM...CSG LONG TERM....CSG AVIATION.....MJ CLIMATE......CSG