Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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415 FXUS63 KLMK 010538 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 138 AM EDT Wed May 1 2024 .KEY MESSAGES... * Chance of fog tonight in the Lake Cumberland and Bluegrass regions. * Dry and warm Wednesday and Thursday with highs in the 80s. * Showers and thunderstorms likely Friday, with a chance of rain lingering over the weekend. Forecast confidence in detailed timing remains low. && .UPDATE... Issued at 916 PM EDT Tue Apr 30 2024 Sfc high centered just to our southeast will keep skies clear and winds light overnight. Quiet and comfortably cool weather for the overnight. The only concern for the overnight remains the possibility of some fog from around the Lake Cumberland region stretching into the Bluegrass and even along the KY/TN border by morning. No changes have been made to the forecast at this time. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 328 PM EDT Tue Apr 30 2024 Currently, we have mostly zonal flow above with high pressure at the surface. With a surface high sitting off to our southwest over western Kentucky and extending down the Mississippi Valley, surface winds are staying out of the northwest over southern Indiana and central Kentucky through the rest of the day. Skies are clear over much of Indiana, but scattered cumulus begins to increase across southern Indiana and central Kentucky. Skies become broken and overcast over eastern Kentucky. The clearing trend will continue through the afternoon and evening hours. Tonight, winds will go calm as the surface high passes east over the CWA. Calm wind and clear skies will help increase radiative cooling, resulting in fog in areas with high ground moisture. Believe the best chance of fog will be over eastern Kentucky, but fog is expected to extend westward through the Lake Cumberland Region towards Bowling Green and into the eastern Bluegrass. Basically the worst of any fog development is expected to remain along and southeast of a line from Bowling Green to Lexington. Low temperatures are expected to dip down into the low to mid 50s. Tomorrow, on the backside of the surface high, winds will begin the day out of the south, and as the high slides to the east, winds will veer towards the southwest as they increase to 5-10 mph. Skies are expected to remain dry for the most part, but as a weak cold front approaches from the northwest early in the day, a few very light showers/sprinkles could affect parts of southern Indiana before dissipating. A near surface dry layer will also help to limit precipitation from reaching the ground. Most areas will only see some scattered mid-level clouds overhead from this front. Highs are expected to reach the low to mid 80. A few on the eastern edge of the CWA will likely only reach the upper 70s. && .LONG TERM /TONIGHT THROUGH TUESDAY/... Issued at 328 PM EDT Tue Apr 30 2024 ========== Long Term Overview ========== Mainly a zonal flow in the upper levels with lower level ridging will be at play for Wednesday night and into Thursday. Sfc high pressure will be centered somewhere to our southeast, which will promote a WAA regime. Dry and hot expected for Thursday as we are deep within the warm sector of a large low pressure system. That upper low pressure system over the High Plains will extend a cold front far south through much of the central US. This cold front will bring shower and storm chances for Friday. Cold front should push east of the region Saturday, which may result in drier weather by the afternoon hours for most. Confidence remains limited, but guidance appears to be in somewhat better agreement today. After a short break in precip activity on Saturday, another wave within the primary upper trough looks to spin through, bringing another shot of precip for Sunday or into early next week. ========== Heat Concerns for Thursday ========== Temperatures surge for Thursday with subsidence aloft and sfc high pressure across the area. Southerly wind component will add to the WAA pattern in place. Deterministic guidance generally has good agree on 1000-850 mb thicknesses that support at least mid-80s Thursday afternoon. However, 50% of the NBM v42. members suggest seeing temps exceed 90F Thursday afternoon for areas west of US-127. Upper 80s look like a sure bet, with the urban islands possibly closer to 90F. It does not appear we`ll threaten the high temperature record at SDF (94F in 1959) or BWG (93F in 1901), but LEX may be in jeopardy. Their record high for May 2 is 88F (1959). If you`re planning to spend alot of time outdoors on Thursday, be sure to practice heat safety be staying properly hydrated and taking breaks indoors if possible. Our experimental HeatRisk index highlights minor impacts for Kentucky. Minor impacts affects primarily those individuals extremely sensitive to heat, especially when outdoors without effective cooling and/or adequate hydration. ========== Thunder Concerns for Friday ========== Adequate moisture and forcing ahead and along an approaching cold front will drive increasing precip chances for Friday. PWATs could exceed 1.5", which would be above the 90th percentile for sounding climatology. While rain is not a main concern for any outdoor events taking place in the state this week, lightning and thunder are concerns. Model soundings show skinny CAPE profiles, with sfc based instability generally above 1000 J/kg by the afternoon hours. If there`s any good news, it`s that we lack any substantial shear for severe storms. Certainly see the possibility for some strong storms with heavy rain rates given the instability profiles and available moisture, but overall coverage should be numerous to widespread showers with scattered/embedded thunderstorms. Cold front is expected to pass through Friday night or early Saturday morning, resulting in lower PoPs as we get into the weekend. QPF for Friday is a broad-brushed 0.25-0.50" of rain, with some locally higher amounts possible given the convective nature. ========== Uncertainty for Saturday ========== Still expect to have a brief period of drier conditions in the wake of FROPA, which perhaps persists deeper into the afternoon hours. Ensembles sill show considerable spread, but deterministic runs show drier conditions for Saturday afternoon. Will stick with the NBM general 30-40% chance, though could see these chances decrease in future forecast packages when data comes into better agreement. && .AVIATION /06Z TAFS THROUGH 12Z THURSDAY/... Issued at 137 AM EDT Wed May 1 2024 VFR conditions will prevail through much of the period. Fog will likely impact visibility briefly this morning at RGA, but confidence in any impacts from fog is much lower at the other terminals. RGA is most likely to see IFR/LIFR vis in dense fog through sunrise. LEX may see some brief vis reductions after 08Z, most likely in the MVFR range. Cannot rule out brief IFR, however. SDF/BWG/HNB appear likely to remain VFR. Calm to very light southerly winds are expected through sunrise, with winds veering southwesterly and increasing to 5-10 mph by late morning. A SCT cu field will take shape across southern IN and the northern half of central KY late this afternoon and evening as moisture pools along a weak cold front. There is a 10% chance for an isolated shower/storm near HNB after 20Z. Otherwise, dry weather will continue. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...BTN SHORT TERM...KDW LONG TERM...CJP AVIATION...EBW