FXUS63 KOAX 181124 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 624 AM CDT Mon May 18 2026 .KEY MESSAGES... - Potential for more severe weather on Monday, mainly across southeast Nebraska and southwest Iowa. Large hail, damaging winds, strong tornadoes, and flash flooding will all be possible. - Cooler weather moves in on Tuesday with potential for morning frost for northeast Nebraska on Wednesday. - Another active pattern may set up going into next weekend with chances for more storms, and possibly severe weather. && .DISCUSSION... Issued at 1155 PM CDT Sun May 17 2026 The line of storms has cleared east of the area but much of southeast Nebraska and southwest Iowa remain under the stratiform rain shield with some embedded weak thunderstorms. This likely won't completely clear until closer to 7am Monday morning. Going into Monday we're going to be watching to see where the cold front stalls, which will help determine our area of potential severe weather Monday evening. Monday will start out cloudy, with scattered light rain showers across much of the area north and west of the cold front stalled across our area. Through the late morning into the afternoon we'll see clouds gradually clear in areas south and east of the cold front. Areas north of the cold front will stay cloudy. The upper-level shortwave arrives, kicking off storm initiation around 2-4PM. Storms that develop in the warm sector will have ample instability and shear to grow into discrete supercells with potential for large hail, damaging winds, and strong tornadoes. Expect similar storm evolution, growing into a QLCS with embedded supercells, which exits our area by 10PM. Several CAMs show a second line of storms which develops around 8-9PM over our western counties and moves through potentially bringing another chance for severe hail and damaging winds. These storms will be elevated in nature, but may still have 1500 J/kg of elevated MUCAPE to work with. This second line clears by midnight, bringing an end to the long, several day stretch of severe weather. We'll see the cold front clear well to the south and east of our area by Tuesday, putting a cooler Canadian air mass in place across the region. Tuesday will start out cloudy once again, but really clear by the afternoon as high pressure builds over our area. High temperatures on Tuesday will only reach into the upper 50s to mid 60s. With clear skies and nearly calm winds, this lends to potential for frost early Wednesday. Overnight lows will drop into the mid 30s for northeast Nebraska to low 40s across southeast Nebraska and southwest Iowa. Cooler weather holds into Wednesday though we do see a reversal to southerly winds and start to advect moisture back into the region. An upper-level shortwave could potentially bring a few showers to the area Wednesday afternoon and evening, but the ensembles haven't picked up on this latest change in the deterministic guidance. In any case, this wouldn't be anything impactful. A better chance for showers and storms moves in Thursday as the longwave trough that's been nearly stationary over the western US shifts eastward toward our area. With temperatures still in the sixties for highs, I wouldn't anticipate much of a severe weather threat with this system for our area. Temperatures start to rebound on Friday though as we see enhanced warm air advection ahead of a deepening surface low which develops on the lee side of the Rockies over eastern Colorado and western Nebraska. Depending on the track of this system, we could potentially see more active weather next weekend with several chances for storms. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 616 AM CDT Mon May 18 2026 A complex aviation forecast is set out, with MVFR toIFR conditions expected to quickly take hold for the remainder of the area terminals, with the worst of the restrictions lasting through the better part of the morning hours, driven by lower ceilings. Winds will be on the increase later this afternoon and evening, with a very short distance between northerly winds and south-southeasterly winds to the east of KOMA. Strong storms are anticipated to spread northward from southeast Nebraska late this afternoon into the evening hours. We've expanded the time that thunder covers in the TAFs, due to increasing confidence that widespread thunder activity will linger past 00z. KOFK looks to dodge thunder chances with rain early this evening, with the back edge of the activity sweeping through and bringing improving ceilings through tomorrow morning. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch through Tuesday morning for NEZ065-066-068-078- 088>093. IA...None. && $$ DISCUSSION...McCoy AVIATION...Petersen