Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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769 FXUS63 KOAX 302342 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 642 PM CDT Thu Jul 30 2026 .KEY MESSAGES... - A line of thunderstorms will move across the region tonight into Friday morning. Damaging wind and very heavy rainfall will be possible with the initial line of storms, along with small hail. - Slightly cooler Friday into the weekend, with highs mostly in the lower to mid 80s. && .DISCUSSION... Issued at 158 PM CDT Thu Jul 30 2026 A shortwave rounding the pinnacle of the central CONUS ridge has been producing showers across eastern Nebraska today. The environment has been conducive to heavy rain as moisture has been advecting from the Gulf over the past 36+ hours. PWAT values are anomalous for the season at about 2" which is in the 99th percentile for late July / early August (NAEFS). The northern half of the area continues to record rain this afternoon. Rainfall rates of 2-3" (and one report of 5") an hour were reported around sunrise. With a broad shield of precip, localized areas of heavy rain are becoming less common. Still, two gauges just south of Plainview, NE (Antelope County) have reported over 5" since midnight with 2-3" common in the rest of the county over the same time period. We`re finally getting some eastward motion with this area, allowing for some clearing over the wettest spots. This should allow for the development of notable instability by this evening. Still, the cloud cover encouraged me to lower forecast highs in most locations by a couple of degrees today. .TONIGHT... The HRRR has offered a couple of solutions over the course of the day today, but has currently resorted back to the original theory of convecting along the cold front diving into north central Nebraska this evening. Current sfc analysis reveals a sfc low in south-central South Dakota and another in northeast Kansas. The trof between the two (and the differential heating provided by today`s cloud cover) should provide a corridor for tonight`s prospective MCS. While supercells may be the first mode noted in south-central SD, upscale growth into a convective cluster is expected as the storms push into Nebraska. Perhaps because of this cloud cover and the baroclinicity it produces, model runs have been driving the strongest winds a bit farther west than yesterday`s did. CAM guidance has very little "severe" wind coming from tonight`s line of storms, especially east of central Nebraska. While diminishing, the primary threat remains damaging wind. Hail and tornadoes are unlikely. I expect this system to have a hard time maintaining shear/cold pool balance. With shear numbers near 20 knots, the cold pool may quickly outrun the complex. The best chance of seeing any severe warnings/damage will be between 7pm and 10pm with the last of the storms pushing out of the southern CWA by 3am (although no longer likely to be severe). Heavy rain is expected as warm cloud depths are near 15k feet and PWATs are cranked. The WPC believes there`s a 15% chance of flash flooding within 25 miles any given point and closer to 25-30% chance in northeast Nebraska given today`s earlier rain. Thankfully, the progressive nature of the line of storms should limit residence time over any given place and help keep that threat to a minimum. Flooding will likely depend on any training elements. .FRIDAY... Behind the system, both dewpoints and temps will slip a couple of degrees. Temps in the upper-70s and lower-80s are 5-10 degrees cooler than normal. A few wrap-around showers are possible in northeast Nebraska and western Iowa and winds there will be breezier under the H5 comma-head. Skies will clear over the course of the day as the showers end and the system departs. Temperatures slowly warm toward seasonal norms by early next week as ridging noses back over the area from the southwest. Global models are in agreement that a deep Canadian low will sweep west to east and try to drag a cold front through the Dakotas. It will get hung up somewhere around here and bring a chance of showers and t-storms Tuesday or Wednesday. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 642 PM CDT Thu Jul 30 2026 Line of strong to severe storms still on track to move through much of the area tonight. Still fairly confident all sites will see storms, but some trends are pointing to OMA being on the very northern edge with maybe a 10-20% chance they get missed. Within in the line expect 30-40 kt gusts to be common, with pockets of 50+ kts in the strongest storms. Behind the line, some guidance hints at patchy fog development into Friday morning with MVFR to IFR ceilings lingering toward mid to late morning. Finally, winds will become northwesterly to northerly behind the storms, with gusts of 25-35 kts during the day. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Nicolaisen AVIATION...CA