Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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043 FXUS63 KOAX 231126 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 626 AM CDT Sun Oct 23 2016 .SHORT TERM...(today through Tuesday night) Issued at 325 AM CDT Sun Oct 23 2016 Thunderstorm and heavy rain chances on Tuesday remain the primary forecast concerns for the shorter term period. Mid level flow pattern was featuring a broad ridge across much of the center of the country this morning, with strong trough moving east off the East Coast and another settling toward the West Coast. Western trough will deepen through Monday as it shifts toward the coast, then eject a significant shortwave into the Plains on Tuesday. Ahead of this wave, ridge will amplify briefly over our area on Monday. At the surface, a cold front, tied to mid level shortwave moving through southern Manitoba this morning, had entered northeast Nebraska just past midnight, and will continue southeast through the rest of eastern Nebraska and southwest Iowa by noon. North winds will follow the front along with cooler and drier air for this afternoon and tonight as high pressure settles into the region. Despite this cool advection regime, plenty of sunshine and decent low level mixing will help temperatures rebound into the 60s most areas with some lower 70s in southeast Nebraska and southwest Iowa this afternoon. Light winds and clear skies will allow most lows tonight to drop into the 30s. Winds will begin to turn southeasterly Monday as surface high slides to the east and pressures lower in the High Plains with approach of Tuesday shortwave. Low level airmass will change little as neutral temperature advection is noted Monday, but filtered insolation will help chilly morning temperatures reach the 60s in the afternoon. Warm advection regime sets up Monday night as low level jet kicks in after midnight, bringing higher theta-e air to mid levels. Models continue to suggest isolated showers are possible in eastern Nebraska before sunrise, but maximum lift/convergence occurs north of Nebraska. Rain/thunder chances will increase markedly during the day Tuesday and especially Tuesday night as surface low attendant to mid level wave deepens in central Nebraska. Gulf moisture return appears to be robust at this time as GFS has been indicating precipitable water values at or above the 90th percentile of seasonal norms, on the order of 1.33 inches representing almost 200 percent of normal. Moisture along with cooling aloft and surging low level temperatures ahead of low combine to produce over 1000 j/kg of MLCAPE as per GFS over at least the southern half of our area Tuesday afternoon and evening. Moderate bulk shear of 30kt or so is also expected. All of this suggests a fairly high chance for preciptation, with some potential for strong thunderstorms along with heavy rain. Finer details will have to be worked out with time, but strongest storms will likely occur over southeast Nebraska and southwest Iowa. High precip chances will continue much of the night, gradually tapering from west to east as trough axis moves east of our CWA by 12Z Wednesday. .LONG TERM...(Wednesday through Saturday) Issued at 325 AM CDT Sun Oct 23 2016 We return to a more tranquil weather pattern for the last half of the week when temperatures will average at or just above seasonal normals. Northwest mid level flow will follow Tuesday`s exiting shortwave before weak ridging sets up late in the week. At the surface, northerly winds and cool advection will rule Wednesday behind Tuesday system, then winds turn to some form of southerly component for the rest of the week. Layer relative humidity progs suggest plenty of sunshine each day as well. There is some divergence in model forecasts by Saturday when ECMWF swings a potent system through the region while the GFS is much less amplified. Neither paints significant precipitation across our area, so will maintain a dry forecast through Saturday. && .AVIATION...
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(For the 12Z TAFS through 12Z Monday morning) Issued at 558 AM CDT Sun Oct 23 2016 VFR conditions expected thru the fcst pd.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE is the U.S. government's official web portal to all federal, state and local government web resources and services.