Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 150421 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1021 PM CST Sat Jan 14 2017 .UPDATE...
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Issued at 1002 PM CST Sat Jan 14 2017 Left exit region of the upper level jet and lift saturating the mid layers enough to produce some patchy sleet and freezing rain across southeast Nebraska this evening. Steadier precipitation is across southern Kansas and Oklahoma. NAM and an early look at the GFS along with the ESRL HRRR/RAP13 trend toward increasing freezing rain coverage across southeast Nebraska between 09-12Z. Subjective surface analysis has mid 20s dewpoints over central Kansas and obs have some patchy lower cigs near Concordia and Manhattan, KS. Enhanced IR imagery in southwest Kansas related to the strengthening low level jet slowly moving northward and increasing mid level lift. Deeper moister will approach southeast Nebraska/isentropic upglide overnight. Made some changes to the ice storm headline to start it a few hours earlier near the Kansas border and to include Seward/Lancaster/Cass counties in with the earlier group vs. waiting until noon due to the HRRR/RAP trends.
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&& .SHORT TERM...(Tonight through Tuesday) Issued at 235 PM CST Sat Jan 14 2017 ...The primary forecast concern is the winter storm that will impact the area Sunday into Monday night... Water vapor imagery as of midday indicates a mid to upper-level low beginning to assume more of an eastward movement near the tip of the Baja spur. Latest model guidance has started to converge on a more consistent track of this system, with it`s location expected to be over western TX/eastern NM at 00z/Mon and near the junction of the NE-KS-MO borders by 00z/Tue. In the low levels, a surface high presently over the mid MO Valley will shift east tonight into Sunday in deference to a deepening lee cyclone over the southern High Plains. This low will develop northeast into northwest MO by 00z/Tue, in tandem with the parent upper-air system. Strengthening southerly low-level winds ahead of the migratory cyclone will advect a seasonably moist air mass present over the southern Plains this morning north into the region, atop a shallow, sub-freeing air mass. Intensifying low-level warm advection and isentropic upglide will foster the northward expansion of a warm-conveyor precipitation shield through the central Plains tonight with this activity moving into southeast NE toward sunrise Sunday. Forecast soundings indicate that the predominant precipitation type will be freezing rain, possibly mixed initially with some sleet. The precipitation shield will subsequently spread north across the remainder of eastern NE and southwest IA Sunday into Sunday night ahead of the approaching deep-layer cyclone. The highest precipitation rates are expected to materialize across the forecast area on Monday in concert with the arrival of the strongest deep-layer forcing for ascent. A change over from freezing rain to rain is forecast to occur Monday morning over southeast NE and far southwest IA as the persistent warm advection pushes surface temperatures to above freezing. Current indications are that this trend will continue north into east- central NE (including the Omaha metro) by Monday afternoon, while over our far northwest counties a snow band will become better organized within the increasingly baroclinic deformation axis. It still appears that the axis of greatest ice accumulation will stretch from near Fairbury and Beatrice through east-central NE into southwest IA where amounts will range from around a half inch on the western end to about 0.35" from Omaha eastward. Highest snowfall amounts are expected over our far northwest counties where three to four inches are possible. Given the growing model consensus with the track of this weather system, enough confidence exists for an upgrade to an ice storm warning from Sunday through much of Monday night for all but our northwest counties. There, the combination of accumulating ice and snow warrants a winter storm warning, which will go into effect Sunday night and similarly continue through most of Monday night. .LONG TERM...(Tuesday night through Saturday) Issued at 235 PM CST Sat Jan 14 2017 A phase change from rain or freezing rain to light snow will occur Monday night along the trailing deformation precipitation band as it advances east/southeast across the area. By this time, the stronger forcing for ascent and higher moisture content will have shifted to the east/northeast of the region, so snowfall amounts should remain light. By the middle of the upcoming week, building heights aloft and enhanced downslope flow in the low levels will yield considerably warmer temperatures with afternoon highs rising into the 40s. Runoff from the Sunday-Monday system coupled with ice melt associated with these warmer temperatures could result a rise in area streams and perhaps some ice jam activity. By next Friday into the weekend, model spread increases with regard to the evolution of the next major trough over the western CONUS. Regardless of the model differences, it does look like precipitation chances will increase during that time. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 530 PM CST Sat Jan 14 2017 Conditions are expected to slowly deteriorate on Sunday. Mid clouds will thicken overnight, especially at KOMA and KLNK. MVFR ceilings should develop by late morning or early afternoon - especially at KLNK- with MVFR to IFR visibilities possible as well. && .OAX WATCHES/WARNINGS/ADVISORIES...
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NE...Ice Storm Warning from noon Sunday to 3 AM CST Tuesday for NEZ015-032>034-042>045-050>053-067. Ice Storm Warning from 3 AM Sunday to 3 AM CST Tuesday for NEZ065-066-068-078-088>093. Winter Storm Warning from 6 PM Sunday to 3 AM CST Tuesday for NEZ011-012-016>018-030-031. IA...Ice Storm Warning from noon Sunday to 3 AM CST Tuesday for IAZ043-055-056-069-079-080-090-091.
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&& $$ UPDATE...Zapotocny SHORT TERM...Mead LONG TERM...Mead AVIATION...Miller is the U.S. government's official web portal to all federal, state and local government web resources and services.