Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 201132 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 632 AM CDT Tue Mar 20 2018 .SHORT TERM...(Today through Thursday) Issued at 318 AM CDT Tue Mar 20 2018 A weak mid-level vorticity lobe and attendant precipitation band will translate through the area this morning with light rain temporarily mixing with or changing to light snow before ending or transitioning to drizzle as the stronger forcing for ascent shifts east. The radar presentation as of 0800z is rather unimpressive with highest precipitation rates (~0.02-0.05/hr) associated with rain per surface observations. Based on current radar trends and latest short-term model guidance, any snow accumulation should remain low and generally less than a half an inch. Lingering cloud cover and light precipitation (especially across the eastern part of the CWA) will once again limit daytime heating with highs today mainly in the lower to mid 40s. However by Wednesday, decreasing clouds coupled with building mid-level heights will yield warmer temperatures with afternoon readings in the upper 40s to upper 50s. Wednesday night into Thursday, model guidance suggests that warm advection and isentropic upglide within the exit region of a low- level jet will foster a swath of light rain across portions of western into central IA, to the immediate north/northeast of a weak surface warm front. Our southwest IA counties will be on the western periphery of that precipitation where we will indicate slight-chance PoPs. To the west of the front, south to southwest low-level winds will allow temperatures to warm into the 60s with mid to upper 50s forecast along and to the east/northeast of the boundary from northeast NE into west-central IA. .LONG TERM...(Thursday night through Monday) Issued at 318 AM CDT Tue Mar 20 2018 Latest medium-range guidance continues to indicate an active pattern over the mid-MO Valley through much of the extended forecast period. These data suggest that an amplified ridge will overspread the Great Plains Thursday night into Friday ahead of a low-amplitude perturbation moving from the Rockies into the High Plains. Strengthening warm advection ahead of that disturbance will support a chance of light rain on Friday. By Friday night into Saturday, it appears that the High-Plains disturbance will amplify as it moves through the region, driving the deepening of a surface low which is forecast to track to our south. Nonetheless, steepening lapse rates and increasing moisture content will support scattered showers and a few thunderstorms as the synoptic system moves through the area. On Sunday, a short-wave trough will traverse the northern Plains with an associated surface cold front focusing precipitation chances over the mid-MO Valley. By early next week, the GFS progresses a low-amplitude trough through the central U.S., whereas the ECMWF and Canadian models depict broader troughing lagging west over the Rockies. As such, forecast confidence is low during that time frame. && .AVIATION...
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(For the 12Z TAFS through 12Z Wednesday morning) Issued at 626 AM CDT Tue Mar 20 2018 IFR conditions will start off the period this morning through 18Z as band of mixed precip associated with a weak mid level trough moves across the area. After 18Z further weakening of the trough is indicated along with a secondary wave over the northern plains. MVFR conditions are expected to develop during this time and with further translation east after 00Z VFR conditions are expected to develop after 06Z.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...Fobert is the U.S. government's official web portal to all federal, state and local government web resources and services.