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Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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980 FXUS63 KOAX 142303 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 603 PM CDT Wed Aug 14 2024 .KEY MESSAGES... - Severe storms are possible this evening (10-20% chance). Large hail, damaging winds, tornadoes, and localized heavy rain leading to flooding will be possible. - There will be another chance for severe storms Thursday afternoon and evening (5-15%) with primary hazards being damaging winds and large hail. - Temperatures stay seasonably warm through early next week with additional chances for nighttime storms. && .DISCUSSION... Issued at 153 PM CDT Wed Aug 14 2024 This afternoon - tonight: Skies are clearing across eastern Nebraska and southwest Iowa this afternoon, preparing our area for the potential for severe storms this evening. A shortwave trough will bring a dry line boundary through triggering storms sometime between 5 and 8 PM, with some CAMs showing earlier convection in Kansas expanding north and developing storms near Gage County around 5 to 6 PM, and the HRRR holding off on convection until closer to 8 PM. In either case, the environment is looking very unstable this afternoon with 3000-4000 J/kg of SB CAPE and strong low-level shear. Some models have as much as 400+ m2/s2 of 0-3km shear. Looking closer to the ground, 0-1km shear will be 200+ m2/s2. This is looking like a much better set-up for severe weather than 24 hours ago, with potential for 2+ inch hail and damaging winds of 75 mph. Tornadoes will also be possible due to the high amount of low-level shear, and LCLs below 1000 m. The area of greatest potential for severe weather is generally east of Highway 77 in Nebraska through southwest Iowa. We`re expecting storms to develop initially into supercells, merging into a line around or just west of the Missouri River. Once the line develops, the tornado threat will lessen, but not completely go away, and transition into more of a damaging wind and heavy rain threat. The severe weather threat should be out of our area by midnight at the latest. Thursday: We have another severe weather threat on Thursday as another shortwave moves through during the afternoon/evening. This looks less menacing as we won`t be quite as unstable, with SB CAPE only around 1800-2500 J/kg, and significantly less low-level shear. There will still be sufficient shear and instability for a severe potential, however, with the greatest threats being large hail up to half-dollar-size and damaging winds of 60 mph. These storms appear to initiate north of I-80 and track into southeast Nebraska and southwest Iowa during the evening. They will likely be out of our area by 10 PM. Friday-Tuesday: Over the weekend we see the summertime ridge build back up over the Rocky Mountain region, with temperatures trending upward across our area. Dry weather is expected on Friday through the day on Saturday, but we`ll have to watch Saturday night into Sunday as the UL-Jet moves across our area for the potential for the development of an overnight MCS. Several models develop one, but vary in location of the system from as far north as the Dakotas to right over our area. With more of the models staying dry over our area, right now precipitation potential is low around 15-20%. Early next week we see the ridge expand eastward leading to seasonably warm daytime temperatures and additional chances for nighttime storm potential. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 603 PM CDT Wed Aug 14 2024 Showers and thunderstorms are developing across portions of eastern NE as of 6 PM (23z) and that activity will become increasingly widespread over the next 2-4 hours with KLNK and KOMA the most likely locations to be impacted. MVFR to potentially IFR conditions are possible in the heaviest downpours with locally strong wind gusts as well. The storms are expected to shift east of the area by 05-06z with winds switching to west and then northwest. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch until 4 AM CDT Thursday for NEZ052-053-067. IA...Flood Watch until 4 AM CDT Thursday for IAZ079-080-090-091. && $$ DISCUSSION...McCoy AVIATION...Mead