Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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460 FXUS63 KLMK 122309 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 709 PM EDT Sun May 12 2024 .KEY MESSAGES... * Active pattern this week with almost daily chances of showers and storms through Friday. Best chance for a dry day will be Wednesday afternoon and Thursday. Severe weather is not expected. && .SHORT TERM /THROUGH MONDAY/... Issued at 328 PM EDT Sun May 12 2024 Afternoon satellite imagery and observations show mostly sunny skies across southern IN and central KY. Surface high pressure ridge was noted from central TN northeast into eastern OH which will set up a southwest flow regime for our region. Afternoon temps were quite pleasant with readings in the 72-78 degree range. For the remainder of the afternoon hours, no significant weather is expected. Temps will cool into the lower 70s by evening. For the overnight period, mostly clear skies are expected this early this evening. As the night wears on and the ridge axis shifts east, we`ll see a gradual increase in high cloud cover. This will keep temps from dipping too much with most locations seeing lows in the mid 50s, with the cooler valleys dropping into the lower 50s. For Monday, an upper level shortwave trough axis over the Plains will slowly move east while deepening. Synoptic scale forcing for lift will overspread the region during the afternoon hours. Much of the data suggests a relatively dry morning period, but scattered rain showers are likely to become more widespread in the mid-late afternoon period. Area averaged model soundings show very little in the wave of instability and wind shear values are quite weak (less than 20kts). So while, I can`t rule out a rumble of thunder here or there, the threat of organized/severe convection is very low. Highs will likely see a gradient across the region. The cooler spots will be in the southwest with highs in the 70-75 degree range. For our north-central and east-central zones, highs of 75-80 are expected. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Issued at 328 PM EDT Sun May 12 2024 Monday night through Wednesday... The medium range forecast starts off unsettled Monday night into Wednesday as a slow-moving closed low meanders eastward from Missouri across the Ohio Valley. Scattered showers are likely Monday night as low-level WAA and moist isentropic ascent increase ahead of the low pressure system. Forecast soundings show a rather moist column with limited instability. While PW rises to 1.2-1.4 inches, PW and IVT are not significantly anomalous (+1.0-1.5 NAEFS SD). The showers will be efficient rain producers, but fairly typically weather for mid-May. An isolated rumble of thunder will be possible with lows in the low 60s. Rain chances are maximized Tuesday into Tuesday night as the low moves directly overhead, with deep lift and moisture. Some areas could destabilize diurnally, but moisture/clouds will keep CAPE values in check. Plus, deep-layer shear will remain weak, so severe weather is not anticipated. Isolated to scattered storms may produce locally heavy downpours, gusty winds, and lightning. Rainfall amounts of 0.75-1.25 inches are possible through Wednesday, with some locally convectively-enhanced totals not out of the question. This could result in some ponding and minor flooding issues in low- lying or flood-prone areas, but significant flooding is not expected. Rain chances linger into Wednesday with moisture wrapping around the slow-moving system, but an overall drier trend is expected from west to east Wednesday afternoon and evening. Given the moist environment, diurnal temperature ranges will be smaller with highs in the 70s and lows near 60 F. Wednesday night through Saturday... Shortwave ridging building east over the Ohio Valley will bring dry weather Wednesday night through Thursday. Look for mostly clear to partly cloudy skies with lows in the 50s and highs in the upper 70s to near 80 F. Rain chances increase once again Thursday night ahead of troughing over the Plains and Midwest. This weather system will drag a cold front toward the region by Friday-Friday night with what should be plenty of lift and abundant moisture. Some thunderstorms will be possible, though available instability is unclear at this time range. At this point, the risk for severe weather appears low. && .AVIATION /00Z TAFS THROUGH 06Z TUESDAY/... Issued at 709 PM EDT Sun May 12 2024 VFR conditions expected for most of the valid TAF period. Basically a wind forecast through midday Monday, as winds currently out of the WSW will slacken and switch to SE overnight, and cirrus will increase from the west. We`ll transition into more of a return flow regime during the day on Monday with winds picking up out the south. Look for sustained 10-12 kt with a few afternoon gusts near 20 kt. Ceilings will lower through the afternoon, with light rain developing late afternoon at SDF, BWG, and HNB. Confidence in the cig forecast is limited as we could go MVFR, so for now will keep it above 2000 feet. Can`t rule out thunder at HNB, but it`s a low enough probability to not include it this far ahead of time. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...MJ LONG TERM...EBW AVIATION...RAS