Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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889 FXUS63 KOAX 172329 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 529 PM CST Sat Feb 17 2018 .SHORT TERM...(Tonight through Tuesday) Issued at 345 PM CST Sat Feb 17 2018 ...Couple of Periods of Freezing Drizzle and Light Snow Sunday night into Tuesday morning... Forecast concerns over the next few days will be temperatures, winds, precipitation type and coverage, and if headlines will be needed. Water vapor satellite imagery, radar, and upper air observations from this morning revealed a fast-moving couple of shortwaves that brought light snow to parts of northeast Nebraska and western Iowa. Although most of the reports were a dusting to an inch and a half, it created multiple car accidents on I80 and I35 in central Iowa. Behind this system we had sunshine, gusty northwest winds, and temperatures mostly in the 40s and 50s. Visible satellite imagery shows a few patchy cloud spreading into northeast Nebraska about 1500 to 3500ft and some cooler temperatures in the 30s. Tonight, a 50 to 70kt low level jet develops over central Nebraska and shifts eastward into western Iowa through the day. This will feed into an area of low pressure from South Dakota into Minnesota with accumulating snow for those regions. Challenging forecast Sunday into Monday night as we have mild temperatures for Sunday with windy conditions and may need a wind advisory, then colder air and light precipitation combining to produce a mix or drizzle, freezing drizzle and light snow depending on your location. South winds increase to 20 to 25kts across northeast Nebraska by morning and these stronger winds 20 to 30kts spread eastward across the forecast area during the morning and into the afternoon as the cold front moves into the area. The models (EC/GFS/NAM/SREF) are similar in depicting deteriorating conditions Sunday night, with the forecast soundings moistening the low levels around 5,000ft or below. Temperatures become critical overnight as the models agree that KOFK will drop below freezing something between 03-06z with a low around 19. At KOMA, the low of 31 is between 12-15Z, and KLNK, the low is in the mid to upper 20s, but drops below freezing from 08-12Z with falling temperatures during the day Monday. A variety of precipitation is possible due to highs from around 50 near the South Dakota border to the mid 60s near the Kansas/Missouri border Sunday and the overnight lows ranging from 15 to 45 Monday morning. The forecast soundings show warm air aloft and not enough cold air for ice crystals, therefore we have freezing drizzle mentioned until it is cold enough to mention snow.We have drizzle, freezing drizzle, and light snow mentioned, however there is instability present Sunday night and Monday morning and the NAM does have some convective precipitation. We do have some ice accumulations up to a .1 mainly along and north of I80 (although we do have it as far south as Otoe and Mills Co.) and light snow up to an inch in northeast Nebraska and west central Iowa. With the cold air...north winds 10 to 20kts will also develop Monday. The upper level trough is still to the west and strong h85 flow continues Monday night into Tuesday with the H85 boundary still pushing through the forecast area with another shortwave in the flow. This will produce another round of light precipitation. Light icing with a tenth of an inch is possible from southeast Nebraska into southwest Iowa. May also need to add a little sleet in per the forecast soundings, but add these details later. Light snow of 1 to 3 inches is possible in northeast Nebraska. Boosted northwest winds for this time frame as well. Highs Tuesday should only be in the teens and 20s. .LONG TERM...(Tuesday night through Saturday) Issued at 345 PM CST Sat Feb 17 2018 Cold temperatures with some sub freezing lows and single digits Wednesday morning with diminishing winds. Wind chills should range from zero to 15 below zero. Wednesday highs are forecast to be in the 20s and 30s. Warmer highs in the 30s and 40s Thursday through Saturday. With a boundary in the area Friday, we have a mix mentioned. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 527 PM CST Sat Feb 17 2018 VFR conditions are forecast through Sunday afternoon with scattered to broken high clouds expected. However Low Level Wind Shear will be a concern as south to southwest winds increase to near 65kt from 06Z through 18Z above surface winds around 10 to 20kt. Southerly surface winds will increase into the 20 to 40kt range by 18Z Sunday and continue much of the afternoon. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Zapotocny LONG TERM...Zapotocny AVIATION...Dergan is the U.S. government's official web portal to all federal, state and local government web resources and services.