391 FXUS63 KOAX 271840 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 140 PM CDT Sat Apr 27 2024 .KEY MESSAGES... - Severe thunderstorms Today and Saturday with strong tornadoes, large hail, damaging winds, and flash flooding possible. Greater flooding threat on Saturday night. - Severe thunderstorms possible on Sunday as well, to a lesser degree, but brief tornadoes possible as well. - Storms wrap up by Monday, with warmer temperatures arriving next week. Another round of showers and storms possible Tuesday/Wednesday. && .DISCUSSION... Issued at 139 PM CDT Sat Apr 27 2024 Today and Tomorrow: As of 17z, water vapor imagery shows a deep trough pivoting across the Southern Rockies, with a compact and mature system continuing to move into the Great Lakes Region; sandwiching eastern Nebraska and Iowa in between. At the surface, a deepening surface low is located in southeast Kansas with a warm front extending northeast from it into far northeast Kansas where dewpoints go quickly from the low 50s in southeast Nebraska to 68 degrees in Jackson County Kansas. Storms are developing along this front in northeast Nebraska, with further development expected to increase and lift northward as the afternoon goes on. Effective shear goes from 40 kts or more to 20 kts two to three counties to the north, extending the severe threat area north of the front, wherever it does lift. Deep shear vector orientation continues to line up parallel with the warm front, with very messy and clustered storm modes expected. With the prolonged lift being applied to the area, multiple rounds of showers and storms are expected to move through eastern Nebraska and southwest Iowa into tomorrow. The combination of increased column moisture and somewhat saturated soils from yesterday's activity will result in increased flooding risk in eastern Nebraska and Iowa. Model QPF indicates that some spots may see over 2.5", with the highest chances being along the warm front and where it eventually lifts in southeast Nebraska. The main hazards for the event continue to be damaging hail, wind, flooding, and tornadoes with the highest threat for any tornadic activity being the messy storm modes along and south of the warm front. While the storm threat does decrease north of the warm front, it's not zero owing as far north as to the sufficient instability, strong shear elevated instability that could help root storms close enough to the surface still allow for all hazards as far north as a line from Columbus to Tekamah. In between stronger storms, scattered showers and weaker storms will continue with an increasing threat of flooding into the overnight hours. Showers and storms will be scoured out by around noon Sunday as the main mid-wave and surface low moves through/to the southeast, leaving us to catch our breath once again. Highs Sunday will vary widely from the 50s in northeast Nebraska to low 70s in southeast Nebraska and Iowa. Monday and Beyond: For the upcoming work week, increasing heights are forecast to develop in the absence of weekend's deep systems with the forecast expected to stay busy as smaller and more compact waves move through Tuesday, Wednesday to Friday, and then again possibly Sunday. Highs will remain comfortable in the upper 60s to 70s with gusty winds expected Tuesday. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1214 PM CDT Sat Apr 27 2024 Main concern of the TAF period continues to be shower and storm chances, primarily at KOMA and KLNK. Northeasterly winds are in place right now with scattered storms expected to arrive after 21z for KLNK then KOMA lasting for 1 to 3 hours. After than lighter showers and drizzle will be possible before another chance for thunderstorm activity arrives mid-morning Sunday. Ceiling trends show that the MVFR ceilings near KOFK will spread southeast and arrive at KOMA/KLNK around the 01-02z timeframe before falling into IFR 06z or later. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch through Sunday afternoon for NEZ015>018-030>034- 042>045-050>053-065>068-090>093. IA...Flood Watch through Sunday afternoon for IAZ043-055-056-069- 079-080-090-091. && $$ DISCUSSION...Petersen AVIATION...Petersen