Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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462 FXUS63 KLMK 240528 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 128 AM EDT Fri May 24 2024 ...Updated Aviation Discussion... .KEY MESSAGES... * Stormy pattern with risks of strong to severe storms and localized flooding issues will continue into Monday. * The greatest threat for severe weather will likely come Sunday afternoon into early Monday morning ahead of a cold front. Damaging winds, large hail, and tornadoes will be possible with severe storms. && .SHORT TERM /THROUGH SATURDAY/... Issued at 329 PM EDT Thu May 23 2024 Satellite imagery currently shows a window of clear skies over parts of central and eastern Kentucky. This clearing began farther west and has now pushed to its current location. It was also one of the driving forces for the recently issued Thunderstorm Watch over parts of central and eastern Kentucky (which runs until 8 PM EDT), as well as areas to the south in Tennessee. As with most of the CWA, including southern Indiana and central Kentucky, we continue to see weak shear overall, but there is some instability. MLCAPE values are just shy of 1,500 J/kg, and MUCAPE values are over 2,000 J/kg. Lapse rates and DCAPE values are marginal, around 7.5 C/kg 0-3km and around 800 J/kg respectively. We likely won`t see widespread severe weather with huge hail stones or extreme high winds, but conditions should produce 1" hail with some gusty thunderstorm winds. This activity will work east over the CWA and is expected to be east of our area early tonight. Tonight, we maintain mostly zonal flow overhead with a large surface low over the Western Plains. Farther east, over the Lower Ohio Valley, pressure gradients remain loose, so southerly winds will remain light. Guidance is somewhat mixed with how much skies will clear, but with low level moisture in place and with saturated grounds, fog and/or low stratus is expected over much of the region. Low temperatures are expected to drop into the low to mid 60s. Tomorrow, south winds remain light as zonal flow begins to push a cold front east across the Plains towards the CWA. Moisture rich air will remain over the region throughout the day. With precipitable water values between 1 to 1.5", a low chance of precipitation will be carried during the day. Any morning stratus and fog could be slow to clear before sunshine becomes more likely closer to midday. This would help to increase low level lapse rates and instability ahead of an approaching line of expected evening convection which is mentioned in the long-term discussion. High temperatures are expected to reach into the upper 70s to mid 80s. Most will see the low 80s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 329 PM EDT Thu May 23 2024 A frontal boundary will come sliding toward the region Friday night. Models vary on convective development/persistence ahead of the front, but some show convection pushing into the region Friday evening into the overnight hours. The severity of this feature will be somewhat conditional on its arrival time... an earlier arrival time would favor an atmosphere with less CIN and more instability, while a later arrival would feature less favorable parameters for severe storms. PoPs overnight are generally highest in the early part of the period, with a tapering down toward dawn Saturday. The frontal boundary will slow down and stall near the Ohio River on Saturday. Isolated to scattered showers and storms may develop along and ahead of the frontal boundary Saturday though shear will be quite weak (0-6km shear less than 20kts) so storm severity potential should be very limited. After a lull in precipitation Saturday night, additional showers and storms will accompany a surface warm front as it lifts into the CWA Sunday morning while a strong 850mb LLJ advects in rich, Gulf of Mexico moisture into the region behind it. Our region should be well within the warm sector by Sunday afternoon and be in an environment of strong shear (both low level and deep layer) as well as moderate instability. Multiple rounds of storms are possible Sunday afternoon into Sunday night, but the most widespread activity will likely arrive late Sunday afternoon into Sunday night as a cold front pushes in from the west. While there are some factors that could hamper the impactfulness of this event (i.e., destabilization between waves of showers/storms, strength of capping inversion, etc), the overall synoptic environment is one that would support organized convection capable of damaging winds, large hail, and tornadoes with severe storms. Joint probabilities from the GFS/Euro/Canadian ensembles show >70% chances of SBCAPE exceeding 40kts and 0-6km shear exceeding 40kts over a large portion of the region Sunday into early Monday morning. If everything comes together just right, this could be a potentially significant event. As such, the SPC Day 4 Outlook seems justified given the potential. Some shower and storm activity could continue into Monday as the frontal boundary slowly sags southward, though activity for Memorial Day should be non-severe. Cooler conditions with lower dewpoints will then persist through much of next week. Can`t rule out periodic shower chances after Memorial Day, though the overall theme going into next week is one that features drier/cooler weather. && .AVIATION /06Z TAFS THROUGH 12Z SATURDAY/... Issued at 127 AM EDT Fri May 24 2024 The last of the showers have now exited the region and SKC skies have set up. With good clear, light winds, and recent precip, low stratus has begun to develop and grow. Currently, low stratus is not impacting terminals, however, they will over the remainder of the overnight hours. TEMPO IFR for low stratus and low VIS is noted through sunrise. Steady SSW winds will start in the mid-morning and CIGs will improve to mostly SCT around 4-5kft. Another round of TSRA is forecasted to arrive over BWG in the late afternoon and move SE into the evening. PROB30s were noted in this TAF issuance. Further TAF issuances will be able to narrow this timeframe down. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...KDW LONG TERM...DM AVIATION...SRM