← Previous April 26, 2024 6:24 AM
FXUS63 KOAX 261124 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 624 AM CDT Fri Apr 26 2024 .KEY MESSAGES... - Several rounds of showers and thunderstorms are expected through the weekend. - Severe weather appears likely (>80% chance) during the afternoon and evening hours on both Friday, Saturday, and perhaps Sunday. - Flash flooding is also a concern due to the potential for repeated thunderstorm activity over the same areas. && .DISCUSSION... Issued at 319 AM CDT Fri Apr 26 2024 Today... Multiple rounds of showers and thunderstorms traversed eastern Nebraska and southwest Iowa overnight, fueled by a robust southerly low-level jet. Heavy rain with these storms required the issuance of a handful of flood advisories over parts of northeast Nebraska. Despite the dreary start to the day, expect clouds to begin to thin across parts of southeast Nebraska by early Friday afternoon. Moderate instability will blossom in this region, ahead of an approaching dry line. Strong bulk shear vectors of 40-55kts are possible across much of the forecast area late Friday morning and into the early afternoon, as a low pressure system begins to move through northeast Nebraska. Supercells will become the most likely storm mode Friday afternoon. Given the steep lapse rates, and robust low level jet. Very large hail will be the primary threat, along with a few tornadoes (some of which may be strong). Heavy rain and strong winds would also be possible with any supercell that forms. The current CAM solutions have storms developing around 2 PM and moving out of southwest Iowa around 8 PM. One potentially limiting factor to the Friday afternoon/evening event would be how far north the narrow channel of sufficient instability reaches. Even the latest model solutions vary on how much clearing and atmospheric recovery we will see after noon today. However, it is clear that any supercells that do become established will be capable of producing damage. Friday Night through Saturday... Once the rain shuts down Friday evening, the remainder of the night Friday night into Saturday morning looks quiet, especially for those participating in outdoor activities Saturday morning. However, that break will be short-lived as another round of severe weather potential develops Saturday afternoon by 4 PM and beyond, as a frontal boundary from the first system is reinvigorated by the next closed low moving out of the Rockies. This allows widespread showers/storms to redevelop across the region Saturday night, with the next round of severe storms possible along/south of Interstate 80. Once again, all modes of severe storms would be possible, including another round of supercells with potential tornadoes and very large hail. Given the multiple rounds of storms Saturday night, compounded with the rainfall we received overnight tonight and will receive this evening, we will have to keep a close watch on flooding potential with an increasing risk for flash flooding. Sunday and Beyond... Another round of storms will close out our weekend on Sunday, as the second low pressure system passes through the forecast area. While the best chance for more well-developed/stronger storms will likely remain off to our east, the passage of the surface low through the heart of our CWA brings concerns for a few low-topped supercells with tornadic potential. We finally receive a break from the active weather pattern on Monday and into early next week, with just a few minor showers and storms possible Tuesday and Wednesday. Temperatures will generally top out in the 70s next week, with a few locations reaching the low 80s on Tuesday. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 624 AM CDT Fri Apr 26 2024 Expect some lingering showers and a few storms early in the period. These will give way to MVFR to IFR ceilings and 20 to 30 kt southeasterly wind gusts into early afternoon. There may be a brief break in the clouds, followed by additional storm development, with potential for severe storms. Confidence in storm strength and exact timing at a given TAF site is fairly low, especially with some signs of earlier spotty development, breaks in the main line, and lingering storms following the primary line. That said, the main line should last 1-2 hrs at a given location with potential for large hail, damaging winds, and even a tornado. Behind the storms, expect VFR conditions with clouds gradually scattering out and winds weakening and becoming more southwesterly to westerly. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...KG AVIATION...CA