Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 212318 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 518 PM CST Wed Feb 21 2018 .SHORT TERM...(Tonight through Saturday) Issued at 447 PM CST Wed Feb 21 2018 Timing precip and location of dominate type late tonight through Thursday evening is initial concern followed by Snow event on Saturday. Regional mosaic already showing batch of precip beginning to lift northward into eastern KS. HRRR/RAP13 indicate activity should reach the southern CWA shortly before midnight. Per RAP13 MaxT aloft prog...there will definitely be a fine line separating freezing/frozen precip. As of now, appears likely snow will be the predominate type between midnight tonight and early Thursday morning as it advances northward through the CWA. However, as layer MaxT go above freezing from south to north, and feeder- seeder process begins to weaken, expect snow to give way to light freezing drizzle from south to north, expanding across the rest of the CWA the remainder of the day into the evening hours. Snow accumulations should be relatively even over the CWA ranging from about 1 to 2 inches. Brunt of ice accumulations will be found over southwest IA south of I-80 with anywhere from one to two tenths possible. Over the rest of the CWA, five hundredths to a tenth looks possible. Given this, will post a Winter Weather Advisory to be in effect from late tonight through Thursday evening. Turning to Saturday, a potent system lifting into the central Plains will be the focus for the next snow accumulation event over the region. Synoptic scale forcing will increase substantially as 500mb hgt falls of 15dam precedes a quite potent vort max as it pushes across NE/KS. Associated precip activity will develop within the warm sector of the surface reflection which is progged to be in western KS 12z Saturday. The GFS and CMC are in rather good agreement depicting the axis of heaviest lining up from southwest NE to southeast SD, just to the left of the 500mb HFC track. And as of now, there appears to be a distinct possibility for significant snow accumulations over the northern CWA where dendritic omega will be maximized...per the GFS...advertising over 40 microbars of lift. .LONG TERM...(Saturday night through Wednesday) Issued at 447 PM CST Wed Feb 21 2018 GFS/CMC in agreement extended periods will be dry from Sunday through at least Tuesday before the next chance for precip. Tuesday night and Wednesday, model show a cold front dropping into the central Plains with the possibility a snow/rain mix event. && .AVIATION...
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(For the 00Z TAFS through 00Z Thursday evening) Issued at 518 PM CST Wed Feb 21 2018 A series of weak mid-level disturbances will eject from the southern Rockies into the mid-MO Valley during the forecast period, supporting an increase in clouds and the eventual development of mixed-phase precipitation later tonight through Thursday. Initial precipitation in the form of light snow will spread north across the TAF sites in the 06z-08z time frame and linger into at least mid morning. There are indications in model guidance that a phase change to freezing drizzle will be possible by mid to late morning at KOMA and KLNK. Precipitation rates could increase by late Thursday afternoon into evening as forcing for ascent strengthens over the region. Expect a steady decrease in ceilings and visibilities with the onset of precipitation with prevailing MVFR conditions developing later tonight and persisting through Thursday.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory from 3 AM Thursday to midnight CST Thursday night for NEZ034-044-045-050>053-065>068-090>093. Winter Weather Advisory from 3 AM to 6 PM CST Thursday for NEZ078-088-089. Winter Weather Advisory from 6 AM Thursday to midnight CST Thursday night for NEZ012-015-017-018-031>033-042-043. Winter Weather Advisory from 6 AM to 6 PM CST Thursday for NEZ011-016-030. IA...Winter Weather Advisory from 3 AM Thursday to midnight CST Thursday night for IAZ043-055-056-069-079-080-090-091. && $$ SHORT TERM...DEE LONG TERM...DEE AVIATION...Mead

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