Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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816 FXUS63 KOAX 220440 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1140 PM CDT SAT MAY 21 2016 .SHORT TERM...(tonight through Tuesday) Issued at 315 PM CDT Sat May 21 2016 Thunderstorm chances/intensity the next few days will provide the main forecast challenges. Large scale still shows an amplified mid level pattern with split flow. Closed low at 500 mb was over Oregon...a ridge was over mid America and another trough was over the eastern part of the CONUS. A weak shortwave trough in north/northwest flow in combination with lower tropospheric warm air advection helped produce some isolated to widely scattered showers over parts of the area last night and today. Short range high resolution models tend to show that activity ending...with more isolated activity possible this evening and tonight over the southwest parts of the forecast area. Generally felt that better chances for significant precipitation tonight and Sunday would stay farther to the west... but axis of highest precipitable water does move into our area on Sunday. Tonight...forecast soundings show a decent amount of moisture in the 800 to 700 mb layer...with modest lapse rates above that. If there was a stronger forcing mechanism...would be more confident with rain chances. Instability increases in our area Sunday...but best focus for convection is farther west. Will keep some low pops going Sunday evening but things look better after midnight as cold front moves eastward. That front will likely help focus precipitation into Monday and Tuesday. There does appear to be some potential for severe storms Sunday night into Monday. High temperatures through this period should be mostly in the mid 70s to lower 80s...with lows 55 to 65. .LONG TERM...(Tuesday night through Saturday) Issued at 315 PM CDT Sat May 21 2016 Pattern starts out with a trough extending from Saskatchewan back to off the California coast. The southern part of the trough will progress eastward toward the high plains by late week...and our area should remain in southwest flow aloft. The GFS and ECMWF are in good agreement with that. At the surface...a frontal boundary is expected to be somewhere over or south of the region. Models are not in good agreement with details of the frontal location. Thus...like the past few days...felt compelled to keep at least some mention of thunderstorms through the period. It will not be stormy every day...but it will be very difficult to have high confidence. Potentially...Tuesday night could be the most active. Highs will be mostly in the 70s to lower 80s and lows still in the 55 to 65 range. && .AVIATION...
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(06Z TAFS for KOMA...KLNK...KOFK through 06Z Monday) Issued at 1137 PM CDT Sat May 21 2016 VFR conditions are forecast at eastern Nebraska TAF sites through Sunday evening. Scattered to broken clouds at or above FL060 should prevail through at least 00Z. Some lowering of cigs is likely between 00Z and 06Z when MVFR conditions could approach the KOFK area. Though an isolated shower is possible, any significant precipitation will remain west of TAF sites during the period. Southeast to south winds will increase into the 15 to 25kt range during the 16Z to 00Z period.
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&& .OAX Watches/Warnings/Advisories... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Dergan

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