Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 260455 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1155 PM CDT THU AUG 25 2016 .SHORT TERM...(tonight through Sunday) Issued at 300 PM CDT THU AUG 25 2016 Precipitation chances and the potential for flooding and some severe weather are the primary forecast concerns. Manual 12z upper-air analysis revealed a positively tilted long-wave trough from central Canada to the southwestern U.S. with a sub- tropical high over the Southeast. A resultant southwesterly mid- level flow regime was present over the central Plains with an embedded short-wave trough currently de-amplifying to our northeast. At the surface, early afternoon mesoanalysis placed the primary baroclinic zone from the Ohio Valley west-southwest through northern Missouri and east-central Kansas into the Texas Panhandle. The precipitation shield present earlier today over southeast Nebraska and southwest Iowa has shifted to the east of the area with only light showers or sprinkles observed over south-central Nebraska and north-central Kansas as of 19z. Some of this activity could make it into our area late this afternoon or early evening, though no more than sprinkles are anticipated. Another weak short-wave trough is forecast to track across Kansas overnight, supporting an increased chance of showers and thunderstorms over southeast Nebraska and southwest Iowa. On Friday, the surface front currently stalled to our south will lift north into the area within a strengthening low-level warm advection regime. This forcing coupled with increasing amounts of moisture and instability will support the south-to-north development of showers and thunderstorms through the day. A few strong to severe storms will be possible during afternoon into evening, with the highest probability of occurrence over southeast Nebraska and southwest Iowa where a favorable overlap of "sufficient" shear and instability is forecast to reside. Increasing clouds and areas of convection should hold highs in the 70s. Friday night, a short-wave trough (located over the Great Basin this morning) will translate through the mid Missouri Valley along with an associated surface front, focusing numerous showers and thunderstorms. Recent heavy rainfall over portions of east-central and southeast Nebraska and southwest Iowa has moistened the soil and set stage for considerable run off with any subsequent precipitation. As such, we will be monitoring the situation for flash flood potential as finer-scale details become more clear. Rain chances should diminish from west-to-east on Saturday as the short-wave trough accelerates northeast into the Great Lakes ahead of a powerful polar-branch trough moving across the northern Plains. Decreasing clouds should allow for slightly warmer temperatures in the upper 70s to lower 80s. Saturday night into Sunday, weak low-level warm advection may be sufficient to initiate isolated to widely scattered showers and thunderstorms, mainly across southern portions of the area. Highs will be dependent on the degree of cloudiness and precipitation with readings in the mid 80s possible. .LONG TERM...(Sunday night through Thursday) Issued at 300 PM CDT THU AUG 25 2016 The 12z medium-range guidance indicates that a mid-level ridge will become established over the north-central U.S. during the early to middle part of this upcoming week which will yield high temperatures in the 80s. While the primary low-level baroclinic zone will remain confined to our north, model guidance continues to suggest a low-probability chance of showers and thunderstorms through much of the extended range. && .AVIATION...
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(06Z TAFS for KOFK...KLNK and KOMA.) Issued at 1153 PM CDT THU AUG 25 2016 VFR conditions initially, with shower chances increasing at KLNK/KOMA by 18-21z, then about a 3-5 hour chance for thunderstorms 20-02z. Just shower chances at KOFK by 21z and beyond if at all. Cloud bases eventually thicken to 8000-10000 feet through midday, and eventually to MVFR by 00z and beyond toward the end of the TAF period.
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&& .OAX Watches/Warnings/Advisories... NE...None. IA...None. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...DeWald

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