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Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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251 FXUS63 KLMK 080723 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 323 AM EDT Mon Jul 8 2024 .KEY MESSAGES... * Very warm today with with slowly increasing humidity. * The remnants of Beryl will move into the region Tuesday into early Wednesday. Isolated strong to severe storms will be possible Tuesday afternoon and evening, with heavy rainfall, isolated damaging wind gusts, and brief tornadoes possible. && .SHORT TERM /THROUGH TONIGHT/... Issued at 322 AM EDT Mon Jul 8 2024 Early morning satellite imagery shows partly to mostly cloudy skies across central Kentucky with mainly clear conditions across much of southern Indiana. Early morning temperatures were in the low-mid 60s in the valleys and the typical cooler mesonet locations. Elsewhere temperatures ranged from the upper 60s to the lower 70s. For the remainder of the overnight hours, no significant weather is expected. For today, we`ll remain in a southwest flow aloft with moisture in the column continuing to increase. Partly cloudy skies are expected and highs should be about 1-2 degrees higher than what we saw on Sunday. So we`ll be going with highs again in the upper 80s to the lower 90s. It will be a bit more humid today as dewpoints rise into the mid-upper 60s. Afternoon heat index values will likely top out in the mid-upper 90s. For tonight, stronger moisture advection will continue across the region with skies becoming mostly cloudy. Scattered showers/storms may encroach on our western counties toward dawn Tuesday. Lows will be quite mild with readings mainly in the lower 70s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 322 AM EDT Mon Jul 8 2024 Tuesday through Wednesday Night... An unusually active start to the extended forecast period is expected Tuesday into Wednesday as the remnants of Tropical Cyclone Beryl lift northeast from the mid-Mississippi Valley into the Ohio Valley and Midwest. A pre-existing upper trough over the central U.S. will interact with and ultimately absorb Beryl over the next 48 hours. There is still some dispersion in model guidance in the exact track and speed of Beryl; however, the current consensus would take the storm center from the ArkLaTex Tuesday morning to the Wabash Valley by Wednesday morning before continuing to lift northeast away from the region Wednesday afternoon. This track would take the bulk of the precipitation shield associated with meso-alpha and synoptic scale forcing (i.e., mid-level troughing, frontogenesis, and convergence) on the NW side of the cyclone into IL/IN, with the bulk of the precipitation over our area being driven primarily by convection and forcing from meso-beta and smaller scale boundaries. Immediately ahead of the remnants of TC Beryl, a stout moisture surge will spread over the Tennessee and Ohio Valleys. EPS, GEFS, and GEPS ensemble mean IVT approach model climo max values Tuesday afternoon across western KY, with IVT in excess of the 90th percentile of model climo spreading into central KY and southern IN by Wednesday morning. This will help PW values surge to around or just above 2" by Tuesday evening, which is also in excess of the 90th percentile of model climo. As a result, any showers and thunderstorms which may develop Tuesday afternoon into early Wednesday morning will have the potential to put down localized swaths of heavy rainfall in a short amount of time. However, for the reasons mentioned in the above paragraph, widespread heavy rainfall should slide just northwest of our area. With most of the forecast area expected to fall within the front right quadrant of the sfc low track, the potential for gusty winds and spin-up tornadoes will exist within convectively-driven bands Tuesday afternoon into Tuesday night. While there are multiple complicating factors associated with the amount of severe potential, the amount of destabilization will be the main limiting factor. First, convection southwest of the area on Tuesday may produce widespread mid- and upper-level clouds. Also, a slower northward progression of the system (as in the 03Z RAP) would delay the northward surge of the greatest instability axis until overnight Tuesday night, resulting in less overall instability for storms to work with. However, if instability is sufficient to allow storms to fire Tuesday afternoon, curved and elongated hodographs, as well as enhanced SRH along an effective warm frontal boundary draped across the CWA will lead to an elevated tornado and damaging wind threat. Additionally, effective bulk shear around 40 kt would support some supercells, adding additional tornadic potential. For now, given continued uncertainties in the amount of instability, a Day 2 marginal (level 1/5) risk for severe weather exists, though SPC notes the potential for an increased threat level depending on trends in expected instability. By Wednesday morning, drier westerly flow will begin to wrap around the back side of the sfc low, bringing an end to the severe and heavy rain threat. While isolated to scattered showers and storms will be possible for the day on Wednesday, precipitation amounts should be relatively light. Thursday through next weekend... In the wake of Beryl`s remnants, large scale upper troughing will dissipate and gradually transition to ridging as we head into next weekend. The return of positive height anomalies across much of the central and eastern CONUS will bring warming temperatures, with above normal temps likely next weekend. While an isolated shower or storm cannot be ruled out at this amount of lead time, the lack of any well-defined systems in medium-range guidance would suggest a mainly dry period from Thursday into next weekend. Looking out to 10 days from now, an extended period of hot weather looks likely from next weekend into the following week, as indicated by ensemble guidance and CPC 6-10 day temperature outlook. This heat may lead to worsening drought conditions if not accompanied by consistent rainfall; fortunately, CPC`s precipitation outlook slightly favors above normal precipitation during this period. && .AVIATION /06Z TAFS THROUGH 12Z TUESDAY/... Issued at 322 AM EDT Mon Jul 8 2024 VFR conditions are expected through much of the upcoming TAF period. Light and variable winds are expected overnight with just a thin layer of high cirrus passing overhead. Winds should pick up out of the south during the day and shifting to the southwest by afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...MJ LONG TERM....CSG AVIATION.....MJ