Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 231151 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 551 AM CST Mon Jan 23 2017 .SHORT TERM...(today through Wednesday) Issued at 323 AM CST Mon Jan 23 2017 ...The primary concern in the short term is heavy snow potential across portions of northeast Nebraska Tuesday into Tuesday night... Early-morning water vapor imagery reveals an intense mid-level low over the southern Appalachians with another potent low off the WA/OR coasts. The broader trough associated with the latter system is presently moving onto the West coast and a subsequent eastward translation through the Interior West will occur today. Similar to yesterday at this time, a deck of stratus is advancing south through the forecast area. Deeper mixing on the western edge of these clouds should promote an eastward erosion through the afternoon with warmest temperatures again occurring across our western counties. By tonight into Tuesday, 00z model guidance has started to converge on a solution that depicts a mid to upper-level jet streak and a sizable portion of the western U.S. trough ejecting into the Great Plains with the attendant surface low tracking from western KS to southeast NE or northeast KS by 00z Wed. Strengthening deep-layer forcing for ascent ahead of this synoptic system will yield an increasing chance of mainly light snow across northeast NE tonight with categorical to likely PoPs warranted across the northern two-thirds of the area on Tuesday. Precipitation type across our northern counties will likely remain all snow where adiabatic and latent cooling effects will offset any diurnal warming. Farther south, a rain-snow mix over our central counties will transition to all rain in the south. A change over to all snow will occur from northwest-to-southeast across the area Tuesday night as the cold air deepens with the passage of the surface cyclone to the east. Northwest winds will strengthen considerably at this time, resulting in areas of blowing snow. As mentioned above, we are seeing growing model consensus in the track and timing of this system, as well as with the QPF. These data suggest that the southern extent of a heavy snow band (i.e. greater than four inch accumulations) will likely impact our northern counties where we will maintain the winter storm watch for Tuesday into Wednesday. The ECMWF and more so the Canadian/GEM indicate a more southern evolution of the heavy snow band than the bulk of available guidance. Should these solutions ultimately prove more correct, additional counties will need to be included in any subsequent warning or advisory. South of Interstate 80, it appears that snow amounts will remain an inch or less. Expect snowfall (albeit lighter) to continue Wednesday, especially across far east NE and west IA. Strong northwest winds will contribute to areas of blowing snow with highs ranging from the upper 20s north to mid 30s south. .LONG TERM...(Wednesday night through Sunday) Issued at 323 AM CST Mon Jan 23 2017 North to northwest flow aloft will persist through the long-term forecast period with several embedded vorticity maxima translating southeast through the region from central Canada. One of which will move through the mid MO Valley Thursday night with another on Saturday. Both of these systems will associate with a surge of colder low-level air into the region, along with the potential for some flurries. A more substantial clipper-type system could affect the mid MO Valley next Monday or Monday night when the chance for some light precipitation would increase. && .AVIATION...
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(For the 12Z TAFS through 12Z Tuesday morning) Issued at 551 AM CST Mon Jan 23 2017 IFR/MVFR stratus entrenched across the forecast area this morning. Diurnal mixing will help to erode western edge of stratus by late morning, especially as surface ridge moves east into Iowa. Expect MVFR ceilings to give way to VFR conditions between 19 UTC to 22 UTC. Isentropic ascent in advance of potent upper/surface system that will affect the area Tuesday into Wednesday, will bring low VFR ceilings back into KOFK and perhaps KLNK by 09/10UTC. Could see light precipitation developing KOFK by pre-dawn hours; however, left precipitation chances out for the time being.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Storm Watch from Tuesday morning through Wednesday morning for NEZ011-012-015>018. IA...None. && $$ SHORT TERM...Mead LONG TERM...Mead AVIATION...Fortin

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