Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 130848 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 348 AM CDT Sun Aug 13 2017 .SHORT TERM...(Today through Tuesday) Issued at 349 AM CDT Sun Aug 13 2017 Remnants of MCS continue to track across the CWA this morning. ESRL HRRR depicting location adn intensity the best, and will use it a primary guide in very short term portion of the forecast as far as PoP. Expect spotty showers to linger into late morning across northeast Nebraska/northwest Iowa, but rest of the forecast area will see a lull as isentropic downglide inhibits development through midday. Slow moving upper level trough will provide enough dynamic forcing to regenerate convection along instability axis in advance of surface trough that will extend from north central Nebraska into the Texas panhandle. Another area of focus will be along weak warm front that will extend from surface low in south central South Dakota into northwest Iowa. Mid-level lapse rates will be steepen as compared to Saturday, with models depicting 6-7C/km by 21-00Z and MUCAPES 2000-3500 J/kg. Bulk shear 35-40kts is on the marginal side, but sufficient to sustain updrafts that could produce large hail. CAM and Synoptic models showing variablity in convective initiation and evolution, but have most confidence of development further north, where dynamics will be stronger. As is the case this morning, convection will linger through the overnight into the morning hours of Monday. After convection moves east, feel most of the area will remain mostly late morning until late afternoon Monday afternoon, as upper ridging builds over central plains. Break in precipitation threat is short-lived, as models again spark thunderstorm development due to thermodynamic forcing along quasi- stationary boundary that will arc from Black Hills into Iowa on Monday night. Given storms will be diurnally driven, expect activity to wane by late evening, especially as upper ridge amplifies somewhat in response to trough diving into western U.S. Will keep low chance PoP in place Monday night into Tuesday and warm advection and increasing LLJ could generate elevated convection. .LONG TERM...(Tuesday night through Saturday) Issued at 349 AM CDT Sun Aug 13 2017 More pronounced dynamic and surface forcing being depicted by medium range models Tuesday night into through Wednesday as more amplified upper trough moves across central U.S. Consequence will be decent chance of precipitation for most of the forecast area. Broad cyclonic flow remains across central U.S. through the end of the week per medium range models, though EC/GEM little faster building upper ridge into northern Rockies. As of now, Thursday looks to be the dry and warmest day; however given variance depicted by GEFS members from Thursday onward, that could change. Temperatures will be seasonal and will be dependent on amount of convective debris from storm development. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1140 PM CDT Sat Aug 12 2017 SHRA and TSRA should continue to spread east overnight. Models keep the bulk of precipitation across northeast Nebraska, but also expect at least a few hours of light precipitation to be possible at both KLNK and KOMA. Precipitation could linger into mid morning at KOMA. Ceilings will be mostly above 3000 feet, but vsbys could drop into the MVFR category or lower. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Fortin LONG TERM...Fortin AVIATION...Miller

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