Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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603 FXUS63 KLMK 021408 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 1008 AM EDT Tue Jul 2 2024 .KEY MESSAGES... * Hot and humid Wednesday afternoon and evening with heat index values peaking around 100-105. * Unsettled weather expected Wednesday afternoon through Friday with daily chances of showers/storms. Strong storms will be possible each day. Isolated damaging wind gusts, torrential rainfall, and intense lightning will be the primary hazards. && .UPDATE... Issued at 1008 AM EDT Tue Jul 2 2024 Temperatures are warming up quickly from morning lows under mostly sunny skies. Starting to see low-level moisture also steadily increase from the south, so the air will have a little more `mugginess` to it compared to yesterday. Forecast continues to look dry with warmer air aloft preventing convective development. && .SHORT TERM /THROUGH TONIGHT/... Issued at 321 AM EDT Tue Jul 2 2024 High pressure centered over New York and ridging down much of the East Coast will provide us with a steady south breeze today as upper ridging builds into the region from the southwest. Though moisture around 4-6k` will lead to some scattered cumulus development, there will be plenty of sunshine, combined with the south breeze and rising heights, to reach maximum temperatures around 90 degrees this afternoon. Moisture pulled northward from the Southeast will result in dew points increasing from the mid 50s this morning to the 65-70 degree range by late afternoon. Tonight the East Coast surface ridge will remain in place while a slowly weakening cold front advances from the northwest, reaching a Michigan-Missouri-Texas Panhandle line by Wednesday morning. This will allow the south breeze, around 5 to 10 mph, to continue through the night, leading to a very warm night. Low temperatures will range from around 70 in the eastern and southern Blue Grass to the low/mid 70s along and west of I-65, which is a few degrees below record warm lows for July 3. Any precipitation associated with the cold front will hold off until during the day Wednesday (see below). && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 321 AM EDT Tue Jul 2 2024 Wednesday - Wednesday night... Strong ridging aloft will remain centered over the Southeast on Wednesday as a low pressure system lifts northeast across northern Ontario. Sfc high pressure slowly slides east off the East Coast. A long trailing cold front will extend southwest through the Great Lakes and Mid-MS Valley. Earlier convection is forecast to dissipate upstream over MO/IL Tuesday night, with the weak frontal boundary forecast to sag southeast through IL/IN on Wednesday. As a very moist, humid airmass heats up and destabilizes, convective development appears likely over the Lower OH Valley Wednesday afternoon and evening. Exact mesoscale evolution is still somewhat uncertain. Tuesday night convection could blow debris clouds southeast over portions of southern IN and central KY Wednesday morning, which could modulate daytime heating to some degree. At this time, however, some early day sun looks possible with the morning hours remaining dry. That should allow temps to surge into the lower 90s by mid-afternoon. A few of our typically warmer spots may touch the mid 90s. Heat index values of 100-105+ are forecast during the afternoon and early evening hours. HREF and LREF data point to 1000-2000 J/kg SBCAPE and a very moist airmass characterized by PW values exceeding 2 inches. Scattered convection will be possible in the afternoon and evening hours, particularly across southern IN and northern portions of central KY. The stronger winds aloft will remain well to our north, and deep- layer shear will be limited to 20-25 kts. With a very warm, moist environment, the hail threat looks very low. The main threats with any stronger storms will be localized damaging winds, torrential rainfall, and frequent lightning. Relatively slow storm motions may increase the risk for localized flooding should multiple storms impact the same area. Loosely organized multicell clusters may linger into Wednesday night as the cold front sinks further southeast. It will be a warm, humid night with lows in the low to mid 70s. Thursday - Friday night... A hot, humid airmass will remain in place for the Fourth of July. Remnant convective outflow boundaries may be lingering from late Wednesday activity. In the upper levels, subtle shortwave impulses will continue to stream ENE through the stronger flow across the Midwest and Great Lakes. We do see a subtle uptick in W/SW flow aloft for Thursday afternoon and evening, which will result in slightly stronger deep-layer shear of 30-35 kts. Scattered to numerous showers and storms will be possible, though confidence in timing of individual waves remains very low. Increased cloud cover and precip chances relative to Wednesday should help suppress temps a bit, with highs ranging from the mid 80s to lower 90s. Thursday night will again be quite warm with lows in the low to mid 70s. A stronger upper level trough is forecast to rotate over the Upper Midwest Friday, which will help force a stronger cold front southeast through the forecast area. Expect at least one more round of showers and thunderstorms before cooler, less humid air arrives Friday night in the wake of the cold front. Saturday - Monday... The weekend looks dry and not as hot as weak sfc high pressure builds in behind the cold front. Highs in the mid 80s look likely for Saturday, with upper 80s/possibly near 90 in some spots on Sunday. Low rain chances return early next week as upper level troughing deepens to our west. && .AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 628 AM EDT Tue Jul 2 2024 Today, high pressure will drift from upstate New York to the coast, causing our winds to come in from the south around 7-10kt. Increasing moisture flowing northward from the Gulf will support scattered afternoon cu. Tonight the high will expand along the East Coast while a cold front approaches from the west, sustaining a south breeze here through the night. Wednesday morning the weakening cold front will stretch from Michigan through Missouri to the Texas Panhandle. Shower/storm development ahead of this feature should hold off until mid to late afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...DM SHORT TERM...13 LONG TERM...EBW AVIATION...13