Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 301728 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1228 PM CDT SAT JUL 30 2016 .SHORT TERM...(today through Monday) Issued at 335 AM CDT Sat Jul 30 2016 Early morning water vapor imagery and 30/00z upper-air analysis indicate broad troughing from the Great Lakes into mid Mississippi Valley, a high centered over Nevada, and a resultant northwest mid-level flow regime present from the northern High Plains into the mid and lower Missouri Valleys. Multiple weak perturbations are embedded within this pattern, one of which is currently translating through eastern Nebraska and western Iowa. At the surface, a ridge axis stretched from the upper Mississippi Valley into the mid Missouri Valley as of 07z with the primary baroclinic zone situated to our south from the Ozarks into southwest Kansas. Weak warm advection along a 30-kt southerly LLJ has fostered a broken band of showers and thunderstorms from south-central South Dakota into south-central Nebraska. Some of this activity could drift southeast and potentially affect western portions of our area this morning. Mid and high-level cloudiness associated with the above-mentioned impulse tracking through the region could limit radiational cooling and resultant fog formation toward daybreak. We will monitor subsequent surface observations and make a determination whether to add a mention to the grids. Otherwise, the surface ridge axis will build to the east today with some clouds and less-than-ideal mixing yielding highs in the lower to mid 80s. Tonight into Sunday, mid-level heights will build over the north- central U.S. in advance of an amplifying upstream trough over western Canada. A deepening lee trough over the High Plains will encourage the northward advance of the front currently located to our south. A southwesterly LLJ will strengthen tonight over the central Plains, enhancing warm advection and isentropic ascent to the north of the surface front. The 00z runs of the mesoscale models are in reasonably good agreement in suggesting the development of showers and thunderstorms within this regime across the southern part of our CWA where we have maintained the highest POPs. Some of this activity could linger into Sunday, namely over southeast Nebraska and southwest Iowa, and this could potentially impact daytime highs. Sunday night into Monday, the western Canada system mentioned above will lift northeast into central Canada in response to the progression of the next system onto the Pacific Northwest Coast. This will support the continued building of mid-level heights over the north-central CONUS with a weak front associated with the lead Canadian system sagging south through the northern Plains. A southwesterly LLJ will once again strengthen Sunday night, enhancing lift with thunderstorms possible along and east of the Missouri River. The presence of PW values approaching two inches and the potential for back-building storms could lead to locally heavy rainfall, a situation that we will have to watch. The nocturnal convection should drift deeper into Iowa on Monday with the cessation of the nocturnal LLJ. Assuming early-day clouds clear, a considerable warm up is anticipated with highs ranging from mid 90s over our western counties to upper 80s in the far east. .LONG TERM...(Monday night through Friday) Issued at 335 AM CDT Sat Jul 30 2016 The mid-level ridge will remain intact over the north-central U.S. through Tuesday night before heights are temporarily suppressed by the eastward progression of the above-mentioned Pacific Northwest trough along the International Border. The associated surface front will not move into our area until Thursday, with continued hot conditions ahead of it on Wednesday. The front will remain in the area through the end of this upcoming week, supporting cooler high temperatures and a continued chance of precipitation. && .AVIATION...
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(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1226 PM CDT Sat Jul 30 2016 VFR conditions are expected through much of the TAF cycle. A thunderstorm complex is possible overnight which could bring periods of heavy rain to the airports overnight into Sunday morning. Did add Prob30 groups for these chances and will refine with continued updates. LLWS may also be an issue overnight into the morning hours.
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&& .OAX Watches/Warnings/Advisories... NE...None. IA...None. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...Kern

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