Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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077 FXUS63 KOAX 280849 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 249 AM CST Tue Feb 28 2017 .SHORT TERM...(today through Thursday) Issued at 243 AM CST Tue Feb 28 2017 Warm and moist air advection at low to mid levels is bringing increasing clouds and keeping temperatures mild. Subjective 00Z upper-air analysis indicates a broad upper-level trough in the western US, with west-southwesterly flow across the central US. 500mb heights generally were neutral to rising everywhere except in WA/BC. A potent 150kt upper-level jet streak was noted across UT-CO. An 850mb low was centered in western NE/northeast CO, with 0C+ dewpoints as far north as KOMA in the warm sector ahead of it, though baroclinic zones/fronts remain poorly defined. At 08Z, a 1000mb surface low was centered in south central NE, with surface warm front extending eastward roughly across the I-80 corridor into Iowa. Main forecast concern is precipitation potential today through tonight. Fog has not really materialized in most of the area, with only a site or two in central NE reporting restricted visibilities at this hour. Have kept the mention before 12Z, but think it overall won`t be a mentionable threat for today. Surface low will continue to slide across eastern NE this morning, with baroclinic zones sharpening from surface to mid- levels. Temperatures likely will reach morning (northwest) to midday (central) to early afternoon (southeast) highs before falling behind the cold front/inverted trough. A post-frontal band of precipitation should develop in the afternoon from central NE to northwest IA, and have increased POPs this afternoon. Despite falling temperatures, I do think precipitation will remain all rain in the afternoon. A second band of precipitation looks likely to develop from northeast KS through southeast NE and northwest MO into southwest IA during the evening. As temperatures continue to fall, along with some dynamical cooling, this precipitation may mix with or briefly change to snow before it ends. Have continued to keep essentially nil accumulations (0.1 in a few patchy areas) as precipitation has trended toward ending before the vertical thermodynamic profile really goes to truly favoring snow. In wake of the cold front and as the upper-level trough moves into the Great Lakes, temperatures will temper down toward normal for Wednesday. Temperatures should be a touch cooler yet on Thursday at least in the northeastern half of the CWA as a reinforcing cold air shot pushes toward the Missouri River valley, though readings may nudge up a degree or two in the southern to southwestern CWA as baroclinicity sharpens overall. .LONG TERM...(Thursday night through Monday) Issued at 243 AM CST Tue Feb 28 2017 As the Great Lakes trough moves away and upper-level ridging reaches toward the central US, 500mb heights should rise Thursday night and Friday. Surface winds will turn southerly and mid-level winds southwesterly, bringing moderating temperatures on Friday and well above-normal temperatures for the weekend. Temperatures on both Saturday and Sunday should easily reach the 60s and possibly 70s as 850mb temperatures reach the teens under favorable mixing conditions. An upper-level shortwave has been progged consistently to move across the Dakotas to upper Midwest on Sunday night/Monday, dragging a cold front through the central Plains. The frontal passage looks to remain dry for our area, with the 500mb low deepening and the surface front encountering better moisture to our east. Temperatures will cool down behind the front, but the airmass is not exactly Arctic behind it, and temperatures are likely to merely return to just being somewhat above normal instead of substantially above normal. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1128 PM CST Mon Feb 27 2017 Area of MVFR cigs will spread north ahead of a low pressure system and into eastern Nebraska between 06Z and 12Z. A cold front will quickly follow, with more MVFR cigs just behind the front between 12Z and 18Z. All eastern TAF sites could see MVFR cigs, but KOMA is most likely to have cigs drop below FL020 through 18Z. Low level moisture will also increase, leading to areas of MVFR fog, with some IFR vsbys likely at KOMA between 12Z and 15Z. There is a chance for rain or a mix of rain and snow to develop near KLNK and KOMA after 21Z, which could lead to IFR vsbys again. However the most likely area of development will be southeast of these TAF sites. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Mayes LONG TERM...Mayes AVIATION...Dergan

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