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Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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859 FXUS63 KLMK 070702 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 302 AM EDT Sun Jul 7 2024 .KEY MESSAGES... * Warmer today with dry weather and comfortably low humidity continuing. * Moisture associated with the remnants of tropical cyclone Beryl will move into the Ohio and Tennessee Valleys as early as Tuesday. Heavy rainfall will be possible at times through the middle of next week, though forecast confidence in specific impacts remains low. && .SHORT TERM /THROUGH TONIGHT/... Issued at 302 AM EDT Sun Jul 7 2024 This morning, 1017 mb sfc high pressure is analyzed over the Ohio Valley, with a relatively dry air mass for early July spread across central Kentucky and southern Indiana. Lower humidity in combination with light winds and clear skies has allowed for efficient radiative cooling, with temperatures already dropping into the mid 60s in rural areas while the cities are in the upper 60s and lower 70s as of 06Z. As we head toward sunrise, we`ll drop a few more degrees, with most locations falling into the 60s and even a few upper 50s possible. In rural areas and river valleys, surface moisture may be sufficient for the development of patchy fog, and a few sites have already observed visibility reductions early this morning. Any fog should burn off quickly after sunrise, setting up mostly sunny skies later this morning. Today, predominant high pressure and an axis of unseasonably low PW values along the Ohio Valley will allow for another warm and sunny day across the region. High clouds from convection over the Gulf States will provide some filtering of sunshine, especially along and south of the Western KY/Bluegrass Parkways, while a diurnal cu field would also be expected to develop during the afternoon hours. Winds will be light due to the lack of a well-defined low-level height/pressure gradient, with speeds only around 5 mph this afternoon. Expect temperatures to climb 2-4 degrees higher this afternoon given increasing 1000-850 mb thicknesses; highs should range from the mid 80s to the low 90s. Dewpoints will continue to be quite comfortable for July, as we should mix out into the low-mid 60s this afternoon. Tonight, high pressure will begin to lift northeast as the overall pattern begins to change thanks to the interaction between troughing over the central CONUS and TC Beryl. However, substantial changes in sensible weather should hold off until the daytime hours on Monday, and another night of light winds, mostly clear skies, and seasonably mild temperatures is expected. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 302 AM EDT Sun Jul 7 2024 Well...a very complicated forecast for late Monday into Wednesday with Beryls track towards the northeast after landfall in Lone Star State. The forecast is even more challenging as to the amount of phasing of potent Nrn MS Valley trough. Mon... Low level moisture will begin to steadily return to the OH Valley (after a wonderful weekend respite) as flow becomes solidly southerly. Dew Points go from low 60s Mon morning into the upper 60s and low 70s Monday aftn. Without much in the way of a forcing mechanism in place, any convection that does develop will be isolated in nature and across the Srn Tier of Ky over to the Lake Cumberland region. Depending on cloud cover...Monday might be close to heat advisory levels. Time and cross sections showing a slug of moisture from 400 mb to 200 mb which should keep values in mid to upper 90s but a sultry day with highs in low 90s. If clouds are less than forecast, HIs will be over 100 F for sure. Mon Night-Wed... Forecast is very complicated and uncertain with the remnants of Beryl. The 00z run has a westward shift with GFS and ECM and various timing and speeds. This brings alot more rain into MO/IL and eventually MI The forecast shows a very rainy forecast timeframe, but suspect we are overly pessimistic and likely will be drier than for that long of a duration w.r.t to PoPS and rainfall amounts. However, there is alot of uncertainty with tropical remnants. Having said that, there appears to be a good set up for a potential Predecessor Rain Event (PRE) ahead of the main circulation of Beryl which will need to be watched closely. Right now that appears to be in IL/W Central IN. Thu and beyond... Beryl and its associated moisture should lift out of the region by Thursday or Friday, though we may still stay unsettled at times going into the early weekend as the aforementioned central U.S. trough is slow to move/lift. However, with a 1018 mb sfc high pressure over area on Thu...things will be much more subdued in terms of convection. Cloud cover will move out early Thu morning and temps will will respond and temps will warm up into the lower 90s by next weekend. Weather Tidbits... July 8 1680...The earliest known tornado in the present day US killed 1 person in Cambridge MA. July 9 1982...A Boeing 727 crashed on take off in Kenner LA. Pan Am 759 took off during a thunderstorm and hit a strong microburst killing all 145 on board and 8 people on the ground. July 10 1913...The worlds hottest temperature of 134 F at Death Valley CA. && .AVIATION /06Z TAFS THROUGH 12Z MONDAY/... Issued at 133 AM EDT Sun Jul 7 2024 VFR conditions are expected through most if not all of the current forecast period as high pressure continues to dominate over the region. The one caveat would be brief visibility reductions from patchy fog between now and sunrise. Crossover temp analysis suggests the greatest potential will be at HNB/RGA; have taken out fog mention at BWG, though the forecast remains low confidence and a short-fuse addition may be needed. Otherwise, any lower visibilities should clear by 12-13Z, with high confidence in VFR conditions through the remainder of the current forecast period. Winds will be light and variable through the period. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...CSG LONG TERM...JDG AVIATION...CSG