Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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218 FXUS63 KOAX 190938 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 338 AM CST Fri Jan 19 2018 .SHORT TERM...
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(Today through Sunday) Issued at 333 AM CST Fri Jan 19 2018 Relatively benign weather into Saturday before impending storm system begins affecting our area Sunday. Southerly winds have begun overspreading eastern Nebraska and southwest Iowa, and with a veil of high clouds overhead, temperatures have halted their drop for the most part this morning. Will likely start the day with temps in the low to mid 30s with winds turning more southwesterly with time, suggesting nice warming potential today. However with insolation tempered by high clouds, still will not reach maximum potential. But highs well into the 40s and lower 50s certainly seem reasonable. Southwest winds will turn northwesterly tonight as a weak cold front drops through the area. Southward progression of front looks to be hindered on Saturday by deepening low pressure in the High Plains providing increasing southerly flow across Kansas into our southern CWA. So we could see a wide range of temperatures from north to south if low clouds remain south of southeast Nebraska and southwest Iowa Saturday afternoon. But for now, will maintain thinking low level moisture/clouds will return there, keeping temperatures across the CWA in the lower 40s, still above normal for this time in January. Strong storm system in the High Plains deepens further Saturday night before swinging east and northeast into eastern Kansas by late Sunday afternoon. Increasing isentropic upglide late Saturday night into Sunday morning will lead to drizzle across southeast Nebraska and southwest Iowa where temperatures should be below freezing for a time before temps rise there. Farther north and west, colder air will be more entrenched as north to northeast low level winds limit warming. Meanwhile, mid level moisture will be slow to increase, suggesting a potentially longer period of freezing drizzle is possible in northeast Nebraska and perhaps west central Iowa into the afternoon. Moistening mid levels should commence during the afternoon, providing seeder-feeder ice for a change to snow in northeast Nebraska. While some accumulation up to an inch or so is likely by late in the day there, the bulk of the snow will come later Sunday night as system moves into the Plains. .LONG TERM...(Sunday night through Thursday) Issued at 333 AM CST Fri Jan 19 2018 Potential for a winter storm for northeast Nebraska, and accumulating snows for the rest of eastern Nebraska and southwest Iowa Sunday night into Monday, are the primary forecast concerns this period. Models are in decent agreement this morning in regards to track of low pressure system and attendant potential for heavy snow. Axis may have shifted slightly southeast, but still focuses on a central Nebraska to eastern South Dakota line, including a portion of northeast Nebraska. Snow will likely be ongoing in northeast Nebraska to begin Sunday night, with the changeover to snow gradually working southeast across the rest of eastern Nebraska and southwest Iowa overnight. Surface and mid level low centers tracking through northeast Kansas into southwest then central Iowa places areas north and northwest of Interstate 80 in favored heavy snow location. Given expected QPF and Garcia method calculations, snow totals of greater than 6 inches are possible across northeast Nebraska from Sunday night through Monday morning. And with the potential for some freezing drizzle initially, have decided to issue a winter storm watch for that area. Locations to the south are more uncertain in regards to snow amounts and potential icing, but certainly a variety of winter weather is likely, beginning with drizzle or freezing drizzle and ending with snow Monday afternoon or evening. There is also some potential for convective showers or snow showers for a time in southeast Nebraska and southwest Iowa as cold core of upper low rides across those areas late Sunday night. A tricky system to deal with now, and hopefully will become more clear with later forecasts through the next 36 hours. Beyond Monday, mid level flow flattens out then becomes southwesterly by Thursday, suggesting a rebound in temperatures by then. Not a dramatic cooldown to start with on Tuesday as coldest air follows system to the east quickly. So have highs in the 30s gradually rising into the 40s Tuesday through Thursday.
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&& .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1124 PM CST Thu Jan 18 2018 VFR conditions are expected through the TAF cycle, with scattered to broken cirrus and unrestricted visibility. Winds will be light tonight, ranging from southeasterly to southwesterly. Tomorrow, southwest winds around 5-10kt are expected, becoming light again after 00Z. && .OAX WATCHES/WARNINGS/ADVISORIES...
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NE...Winter Storm Watch from Sunday afternoon through Monday morning for NEZ011-012-015>018-030>033-042. IA...None.
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&& $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...Mayes, signing out!

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