Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 111816 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 116 PM CDT Fri Aug 11 2017 .SHORT TERM...(Today through Sunday) Issued at 255 AM CDT Fri Aug 11 2017 Tranquil sensible weather for the early part of the forecast period. Radiational cooling and lingering low level moisture will be sufficient for MVFR fog development. Discrepancy as to the extent per SREF and NARRE, so will continue with previous forecast qualifier of patchy. Overall, only minor adjustments to previous forecast. Surface high will continue to build into forecast area, with broad cyclonic flow at H5. Temperatures today will be a category below normal due to modest low level cool advection. Saturday will be nearly a repeat, though low level southerly flow will allow some warming to western part of CWA. A short wave drops southeast across northern plains Saturday,but will make relatively slow progress due to block by more substantional Great Lakes shortwave. Jet streak shears shortwave out some what, but there will be enough dynamic forcing to develop convection in the western high plains. Better isentropic forcing will be focused to the best of the forecast area, but there remains some potential for decaying convection to move into far western part of the forecast area. Consensus model reduced PoP slightly, and based on short term model output, this looks reasonable. Better chances for storms on Sunday as temperatures aloft cool somewhat, with lapse rates reducing to 6-7C/km, MUCAPES of about 2K J/Kg and overall wind field sharpens. Remaining shortwave energy still will be battling confluent flow as it moves further east; however, all short term models all signaling for at least scattered storms affecting most of the forecast area. Due to attendant precipitation and clouds, high temperatures will be slightly cooler, with temperatures in the 70s. .LONG TERM...(Sunday night through Thursday) Issued at 255 AM CDT Fri Aug 11 2017 Broad cyclonic to weak northwest flow will continue to dominate large scale through Monday. Upper ridge begins to build over central plains Tuesday-Wednesday, with potent western Canadian shortwave flattening flow late in the week. Temperatures will start to edge back to seasonal levels, and perhaps climbing above norms by late in the week. Upper ridging early in the week will keep forecast dry Monday- Tuesday. Several weak disturbances being hinted at per ensembles as the flow flattens out later in the week, thus intermittent chances of showers and storms expected mid-week on. && .AVIATION...
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(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 113 PM CDT Fri Aug 11 2017 Surface High pressure will move eastward across Eastern Nebraska and Southwest Iowa this afternoon and tonight. VFR conditions will prevail at KOFK, KOMA, and KLNK through 12/18Z.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Fortin LONG TERM...Fortin AVIATION...Smith

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