Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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966 FXUS63 KOAX 280441 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1141 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 /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1133 PM CDT Sat Apr 27 2024 Models continue to struggle with cloud cover and precipitation the next 24 hours. As such there is more uncertainty than usual for this TAF issuance. In general, IFR ceilings are expected to build into all TAF sites with periodic dips into LIFR. The two most likely places for this is KLNK and KOFK, and as such have included TEMPO groups. Rain chances continue to diminish tonight, so have opted to leave rain out of the start of the TAF period. Patchy drizzle may develop across portions of northeast Nebraska (KOFK) between 06Z and 12Z, periodically bringing visibilities down to 3 to 5 miles. The coverage is too low and uncertainty too high to include at TAFs at this time, but the potential is still there (20 to 40% chance). Thunderstorm chances return to far eastern Nebraska and western Iowa (KOMA) tomorrow after 17Z. Will monitor for amendment to include a TEMPO group for thunder overnight tonight. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...Darrah