Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 160515 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1115 PM CST Sun Jan 15 2017 .UPDATE... Issued at 1115 PM CST Sun Jan 15 2017 Forecast remained on track so changes for the overnight into Monday were minor. Heaviest precipitation should spread into the area from the south late tonight into Monday morning. It is looking like wedge of warmer air will work its way into southeast Nebraska and southwest Iowa during the day, at turning the freezing rain over to regular rain for several hours. Then as colder air moves in, expect a change back to freezing rain and or sleet. && .SHORT TERM...(Tonight through Wednesday) Issued at 345 PM CST Sun Jan 15 2017 ...Prolonged Periods of Freezing Rain with Significant Icing for Parts of the Area into Monday ... Early afternoon water vapor imagery indicated the closed mid- tropospheric low pressure system over northern Mexico. The 12Z upper air analysis indicated 80-100+ kt H30 jet segments off the West Coast...across northern Mexico...across the Rockies into the Great Lakes and Ohio Valley. Broad diffluent flow continued for a large area from the NM/TX/CO/wrn OK/KS. Large-scale ascent over the Plains was resulting in a large shield of precipitation across KS, with the northern extent into central Nebraska and southern IA. The 12Z OAX sounding showed drier air from 3-7Kft. Forecast soundings indicate this dry air being overcome this afternoon with periods of light freezing rain/rain depending on the surface temperatures. Latest observations, although initially in the mid 30s...have now dropped to freezing or slightly below freezing with the onset and progressive expansion of precipitation south of a line from Columbus to Fort Calhoun. WSR-88D trends show moderate freezing rain moving across the KS/NE border associated with an embedded vorticity maximum in the southwest to northeast flow aloft across Kansas. Precipitation amounts in this band have been around 0.05 to .1 per hour. Local impacts/conditions should deteriorate with temperatures/surfaces cooling and freezing tonight. The short range models remain in good agreement through the short range forecast period with broad isentropic ascent continuing through the overnight period as the closed h5 low pressure system tracks toward the Texas panhandle toward eastern Kansas by midday Monday and into northwest Kansas by 00Z Monday evening. Ongoing freezing rain will continue tonight with temperatures in the 20s to lower 30s with additional rounds of precipitation later tonight and Monday morning. There may be a mix of freezing and sleet/snow on the northern fringes...and temperatures warm to above freezing toward Falls City Monday morning. With the surface low track remaining to our south from eastern Kansas into northwest Missouri. This warming will be limited to the southeast parts of the forecast area where temperatures warm into the mid and possible upper 30s at KFNB. Elevated instability does approach KFNB by midday Monday, so this will need to be watched. As the colder air works into the system, there may be some light snow with the deformation band in northeast Nebraska. Amounts continue to be in the light range at this time in the 1 to 2 inch range. Left the headlines in place with good confidence on the icing of 0.25 to 0.50 with higher amounts locally, however far northeast Nebraska toward the South Dakota border should see more limited impact. Northwest winds increase as little more into the 10 to 15kt range Monday night. The warming trend for Wednesday still looks on track. .LONG TERM...(Wednesday night through Sunday) Issued at 345 PM CST Sun Jan 15 2017 A mid latitude trough is progged over the central U.S. ahead of a full-latitude trough over the west coast. The EC is a little stronger earlier with moisture being drawn northward Thursday before swinging the closed h5 low eastward. The GFS has the track/moisture more northwestward Thursday night and Friday and a leading wave in the flow from the West Coast rapidly catches up to it Friday night and Saturday then lifts north. The complex...unsettled weather pattern persists Saturday night through Sunday night, with the full latitude trough over the central U.S., however the details vary over where the precipitation will focus. h85 Temperatures are mild for the time of year +6 to +12 deg C cooling to +4 to +6 Friday and below 0 deg C by Sunday. With highs in the 40s...rain would be the predominant precip type...change to snow later in the extended with the colder air. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1115 PM CST Sun Jan 15 2017 Expect IFR or LIFR ceilings overnight and much of Monday. There will be periods of freezing rain, possibly mixed with sleet. Heaviest precipitation should be during the day Monday. Light winds should turn to the north and increase. Conditions should improve at KOFK Monday evening, then at KLNK and KOMA later Monday night. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Ice Storm Warning until 3 AM CST Tuesday for NEZ015-032>034- 042>045-050>053-065>068-078-088>093. Winter Storm Warning until 3 AM CST Tuesday for NEZ011-012- 016>018-030-031. IA...Ice Storm Warning until 3 AM CST Tuesday for IAZ043-055-056-069- 079-080-090-091. && $$ UPDATE...Miller SHORT TERM...Zapotocny LONG TERM...Zapotocny AVIATION...Miller

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