Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 291125 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 625 AM CDT FRI JUL 29 2016 .SHORT TERM...(today through Sunday) Issued at 322 AM CDT Fri Jul 29 2016 Early-morning water vapor imagery and 00z upper-air analysis indicate a low-amplitude short-wave trough and associated mid and upper-level wind maxima translating southeast through the mid Missouri Valley. Forcing for ascent attendant to these features has contributed to a broken band of light showers and a few thunderstorms from south-central South Dakota into southwest Iowa as of 07z. Latest short-term convection-allowing model guidance and 00z parameterized data suggest that light convective precipitation may persist this morning mainly over our western counties before diminishing by afternoon with the passage of the short-wave trough to the southeast. Tonight, another weak impulse is forecast to track across the Dakotas into the upper Mississippi Valley, enhancing low-level warm advection over the Nebraska sandhills into south-central South Dakota. Isolated showers and thunderstorms may materialize within this regime, potentially affecting western portions of northeast Nebraska late tonight into Saturday morning. Saturday into Sunday, mid-level heights will build over the north-central U.S. in advance of a strong short-wave trough translating from the British Columbia coast to the lee of the Canadian Rockies. At the surface, a lee trough will deepen over the High Plains, yielding warming daytime highs and strengthening southeast winds (namely Sunday afternoon). The best precipitation chances appear to be Saturday night into early Sunday across southeast Nebraska and southwest Iowa where warm advection and isentropic ascent are focused along a nocturnally strengthening LLJ. .LONG TERM...(Sunday night through Thursday) Issued at 322 AM CDT Fri Jul 29 2016 The above-mentioned Canadian short-wave trough will lift northeast through central Canada in advance of the next upstream trough tracking from the northeast Pacific into the northern High Plains and south-central Canada by the middle of next week. This will promote building mid-level heights during the early part of this upcoming week, a notion supported by 00z deterministic and GEFS mean guidance. Of interest, the ECMWF and Canadian models suggest that a weak front will settle south through the mid Missouri Valley during that time frame, which would temper daytime highs. In contrast, the deterministic GFS and GEFS mean indicate that the front will remain to our north with daytime highs returning back to the 90s. Based on the mid-level pattern, this latter scenario appears more probable. Mid-level heights will temporarily lower over the north-central CONUS with the passage of the short-wave trough through south- central Canada Wednesday into Thursday, with an associated cold front settling south into the mid Missouri Valley. The arrival of this front will bring increasing precipitation chances and cooler daytime highs. && .AVIATION...
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(For the 12Z TAFS through 12Z Saturday morning) Issued at 625 AM CDT Fri Jul 29 2016 VFR conditions are expected through the TAF period. This morning a few sprinkles are possible as a weak shortwave moves through eastern Nebraska. By this afternoon clouds should break with winds diminishing thereafter and remaining light through the overnight hours.
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&& .OAX Watches/Warnings/Advisories... NE...None. IA...None. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...Pearson

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