Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 212105 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 305 PM CST Sat Jan 21 2017 .SHORT TERM...(Tonight through Tuesday) Issued at 305 PM CST Sat Jan 21 2017 Potential for fog the next few nights and temperatures will be the main forecast concerns through Monday night. Our attention turns to precipitation chances/type/timing by Tuesday. General large scale mid tropospheric pattern featured a ridge over the eastern United States, a closed low over North Dakota with a trough extending from that into Minnesota and a trough from off the Pacific Northwest coast down into the Four Corners region. The system over the southwest states will move eastward tonight and Sunday, but any precipitation associated with that should stay down across Kansas and Missouri. Surface low near the Colorado/Oklahoma border at mid afternoon today will track eastward into northern Arkansas overnight. In our area, the pressure gradient will initially be very light, but tighten a bit with north/northwest winds in the 7 to 12 knot range by late tonight. Some fog could form again tonight, with the most likely locations to see dense fog across southwest Iowa and southeast Nebraska. Will not issue a headline for fog at this point, but like yesterday, that will have to be monitored. The stronger winds later tonight should help limit fog in our northern zones. North/Northwest winds will bring in some cooler air for Sunday and Sunday night. Highs Sunday should reach the upper 30s to mid 40s Sunday afternoon. A surface ridge axis should be over the forecast area at 12Z Monday but then move eastward, with increasing southerly flow. Some model output hints at possible light precipitation in our far northwest counties as early as Monday afternoon, but using a blend of other available output delays chances until Monday night. This seemed to be the best solution for now. The 12Z GFS seemed too fast with its eastward progression of the surface low on Tuesday. A blend of the ECMWF/Canadian/NAM was used, which would put the surface low in central Kansas by early Tuesday evening. Did not go as aggressive as the ECMWF/Canadian/NAM models at this time. It is interesting that the NAM showed impressive mid level frontogenesis in a band from around Hastings to Omaha Tuesday afternoon. .LONG TERM...(Tuesday night through Saturday) Issued at 305 PM CST Sat Jan 21 2017 The low pressure system will continue to lift through the region Tuesday night with a deformation zone likely producing snow. Just exactly where that will be is the problem. Surface winds should also increase from the north/northwest. Precipitation potential will be decreasing Wednesday, based on latest expected timing. The rest of the period from Thursday through Saturday looks mainly dry. Temperatures should be below normal through the period, but slowly moderate. Highs will mainly be in the upper 20s to upper 30s, with lows in the teens to lower 20s. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1142 AM CST Sat Jan 21 2017 VFR conditions are forecast for the first parts of the TAF, however as surface winds decline tonight and reinforcing cool air arrives tonight...look for some MVFR vsbys with patchy fog and return of stratus MVFR/IFR cigs mainly after 06Z. The RAP/NAM are a little more aggressive with the westward extent of the stratus later tonight and Sunday morning. Winds should mostly be under 10kts today and light and variable after 00Z...however will increase from the northwest to 10 to 15kts after 09-12Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Zapotocny

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