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Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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251 FXUS63 KLMK 151434 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 1034 AM EDT Mon Jul 15 2024 .KEY MESSAGES... * Triple-digit heat index values between 100-105 degrees today and Tuesday. * Shower and storm chances look to increase by the middle of this week as a frontal boundary sinks into the area. * Cooler temps in the 80s for Thursday into Saturday. && .UPDATE... Issued at 1034 AM EDT Mon Jul 15 2024 Temperatures so far this morning have warmed into the 80s, and the overall forecast remains in good shape. Some cloud cover over the Bluegrass is what`s left from morning shower and storm activity across our north, which is slightly impacting temps with Mesonet obs showing upper 70s. Otherwise, we still expect temperatures to warm into the upper 90s today, with muggy dewpoints in the lower 70s. This will translate to heat index values between 100 and 105 this afternoon. There was some internal discussion of a Heat Advisory this morning, as you may have seen IND and ILN issue one, but updated forecast grids and guidance keeps us just below criteria, especially with the 2 hour minimum. The SPS will continue as is, along with advertising heat safety in other forecast products and on social media. No changes to the forecast are planned at this time. However, tomorrow appears to be a better candidate for possibly needing an advisory somewhere in our forecast area. Temps tomorrow peak in the upper 90s again, but slightly higher dewpoints may result in heat indices peaking around 101-106. We`ll have those discussions today, and collab with our neighboring offices. && .SHORT TERM /THROUGH TONIGHT/... Issued at 308 AM EDT Mon Jul 15 2024 The main weather impact for today remains the heat and humidity. The combination of afternoon temperatures warming into the mid/upper 90s and once again a steamy, muggy airmass with dew points ranging from the upper 60s to widespread low 70s. All of this leading to heat index values ranging between 100-105 degrees. It is possible there could be a few isolated places that reach 105 or above heat index values but it appears to be very isolated. There are also some potential limiting factors to the heat today and this afternoon. MCS currently working through northern IL/northern IN will approach southern IN and the Ohio River close to daybreak. ACAR soundings out of SDF showed a nice capping inversion around 850mb and hi-res models agree on weakening and dissipating this activity before it reaches the Ohio. While the trend in the models is to keep the CWA dry this morning into the afternoon, current KLVX radar image shows a few returns across southern IN. Decided to bring a 20 PoP to parts of southern IN by around 12z. high/mid clouds associated with the convective debris will likely linger this morning, especially across the northern half of the CWA. Depending on how long the clouds stick around even if they are SCT/FEW could impact how hot it gets at the sfc. Due to the lack of wide spread heat advisory criteria and talking with surrounding WFOs, made the decision to continue the SPS today for the low triple digit heat index values. Cold front coming out of the Great Lakes tonight will spark another MCS over eastern IA and northern IL. Like the one this morning, this will work towards southern IN and the Ohio River between 10-12z. Once again models break and dissipate the activity before it reaches the CWA but went ahead and kept low end PoPs for southern IN towards the pre-dawn hour tomorrow. Lows will remain very warm overnight only dropping into the low/mid 70s with a few of our more urban areas in the upper 70s to even 80. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 308 AM EDT Mon Jul 15 2024 Periods of active weather are anticipated through midweek as a slow moving frontal boundary steadily sinks southward from the Midwest and Great Lakes region. At the start of the forecast period (Tuesday morning), showers and storms may be ongoing across portions of Midwest and Ohio Valley as a decaying MCS pushes southward. Most models prog this activity to weaken and `dry up` as it moves into our CWA, though lingering cloud cover associated with any convection could slow heating down Tuesday. Should we end up with more clear skies vs clouds, Tuesday is shaping up to be a hot one, with many locations reaching mid 90s and heat indices likely exceeding 100 degrees by the afternoon. Models prog new convective development along various mesoscale boundaries by the afternoon that could linger into the overnight hours. Weak/Marginal deep layer shear will limit any sort of severe threat, but gusty winds in downbursts along with heavy rainfall are likely in the strongest storms. The frontal boundary will likely be near the Ohio River by 12z Wednesday morning. Additional convective development is likely along it as it continues its southward trek, and the rain/clouds will keep temperatures a bit cooler compared to previous days readings. The front itself may not push out of the region until Thursday, so expect rain chances to linger through then. Slightly cooler air along with drier conditions and lower dewpoints will gradually work in behind the front to give us a much needed break from the hot/humid conditions experienced earlier in the week. Chances for rain begin to creep back up for some going into the weekend as the frontal boundary begins to waver and slowly lift northward. Models understandably vary on the position of the front this far out in time, but it appears the best chances for any sort of rain/storms will be across our southern/eastern zones (Lake Cumberland region points northeastward). && .AVIATION /12Z TAFS THROUGH 18Z TUESDAY/... Issued at 630 AM EDT Mon Jul 15 2024 Current satellite imagery as well as WSR-88D shows what is left from the MCS from overnight currently in southern and central IN. There remains scattered showers and storms mostly north of our area. It is expected for this activity to continue to dissipate before working into our area. The only impacts appear to be some high to mid clouds around the area and increased winds out of the south-southwest between 5-10kts and gusting to around 15kts this afternoon. Despite the passing systems this morning and again later tonight VFR flight categories remain the prevailing forecast for all TAF sites through the period. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...CJP SHORT TERM...BTN LONG TERM...DM AVIATION...BTN