Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 211725 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1225 PM CDT Sat Oct 21 2017 .SHORT TERM...(Today through Monday) Issued at 313 AM CDT Sat Oct 21 2017 Water vapor loop showing weak impulse moving northeast across the forecast area this morning. System is enhancing isentropic lift along 315K surface, producing small area of showers and storms. Expect this area of showers and storms to continue lifting northeast, though could see upstream development along LLJ moist axis. Attention turns westward by mid-morning as cold front edges into northwest corner of the forecast area. Convective allow models each are depicting scattered convection along the front by 15 UTC. Progressive nature of upper level H5 trough will allow front to make haste across the forecast area, and expect front and convection to be along or east of Missouri River by 21UTC. Forecast models have been diminishing effective instability and shear, so while threat of strong storms will be possible, the severe threat is lessening except for the extreme southeast corner of the forecast area. Expect convection to exit the area by mid- to late evening. Upper flow flattens out somewhat as upper wave deamplifies as it moves northeast. This will allow winds to back to the west- southwest on Sunday, providing some downslope warming, effectively mitigating cooler airmass in wake of front. Temperatures on Sunday look to be near or slightly above normal, so generally in the mid- to upper 60s. Broad cyclonic flow establishes itself over the northern plains/southern Canada and drives another cold front through the area on Monday. Frontal passage appears dry, though could see some virga with any associated clouds. Upper trough amplifies as it dives into eastern U.S., and area will get a glancing blow of cooler air, that will impact temperatures early in the extended period. .LONG TERM...(Monday night through Friday) Issued at 313 AM CDT Sat Oct 21 2017 Temperatures on Tuesday will be about 10 degrees cooler than those seen Sunday and Monday, but will rebound a little on Wednesday as weak upper H5 ridging builds into plains. Warming will not last, as short wave diving into northern Rockies deepens broad cyclonic flow over northern U.S. and drives a front through the area Thursday night into Friday. The latter part of the week looks chilly, with temperatures averaging about 10 degrees below normal. Temperatures by Saturday morning to deep below freezing across the entire forecast area. There is a threat for precipitation Thursday into Friday, and temperature profile suggests potential for rain-snow mix across southern portions of the CWA early Friday. For now, kept chances of precipitation low, as deterministic and ensembles showing variance in solutions. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1223 PM CDT Sat Oct 21 2017 Mainly MVFR ceilings extend across all sites, with showers near KOFK and approaching KLNK. As area of showers approaches KLNK and particularly KOMA, it may also develop embedded thunderstorms. Gusty south to southwest winds ahead of the front and line of showers will switch to northwesterly. Winds likely will be gusty immediately behind the front for an hour or two, then gradually slacken through the rest of the evening and tonight, along with improving ceilings. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Fortin LONG TERM...Fortin AVIATION...Mayes

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