Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 231137 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 637 AM CDT MON MAY 23 2016 .SHORT TERM...(Today through Wednesday) Issued at 1252 AM CDT Mon May 23 2016 8Z subjective surface analysis indicates a cold front situated along a line from KONL to KEAR to KHYS. Temperatures were quite mild with many places reporting around 70 degrees, nearly 15 degrees above normal. A line of showers and thunderstorms have migrated into northeast Nebraska but are losing their surface based characteristics virtually ruling out any severe weather threat early this morning. Expect this line of showers and thunderstorms to continue to diminish this morning as it waddles east. Aloft broad southwesterly flow was noted ahead of an upper level western conus trough. This trough, as it shifts east, will be a major weather maker for our area by the end of the work week and looks to dominate our weather into the weekend. New precipitation development is expected later this morning and into the afternoon ahead of a weak shortwave progged to pass through this evening. Overall severe weather parameters aren`t great, but can`t rule out stronger storms as the atmosphere destabilizes this afternoon. The severe weather threat continues into Tuesday as a more prominent shortwave moves through. For Tuesday it`ll be a question of timing and if the shortwave timing coincides with peak heating, which could very well place the better severe weather threat further west towards Hastings and Kearney. On Wednesday we should see a break, albeit a short one, in the precipitation chances as the boundary layer dries out. .LONG TERM...(Wednesday night through Sunday) Issued at 1252 AM CDT Mon May 23 2016 An unsettled weather pattern is expected through this period as broad southwesterly mid-level flow dominates ahead of the main system by Friday. To start Wednesday evening some low-level drying continues from earlier in the day allowing for a continued break in precipitation. By late in the evening the first of a couple of shortwaves propagate through, potentially bringing a return of precipitation as well. Guidance differs a bit on the location and track of these features. Overall confidence in Wednesday night precipitation isn`t very high as a result. Thursday evening marks the beginning of the period where we could see the best heavy rain potential. Recent guidance suggests areas along the Nebraska/Kansas border and into southwest Iowa will be under the gun for the heaviest rain. Model predicted precipitable water, which tends to be overestimated, is around 1.6 inches in these areas Thursday night. If this were to verify it would be a near record value based on past data collected at the Omaha NWS office. Thursday night will need to be watched for a potential flash flood watch, especially given some rain, possibly heavy, will have fallen in the days prior. By late Friday morning the heavy rain pushes east into central and eastern Iowa as the main upper low traverses the forecast area. As this and the corresponding surface low track through the central Plains, the chance for severe weather on Friday seems increasingly likely. At the moment the better potential would be south into Kansas, but our area will need to be monitored. Thereafter remnant southwesterly flow along with modest available moisture will allow for precipitation chances through Sunday. && .AVIATION...(12Z TAFS for KOMA...KLNK...KOFK through 12Z Tuesday) Issued at 621 AM CDT Mon May 23 2016 A complex weather scenario has unfolded this morning due to the steady weakening of a linear convective system as it entered our northwest CWA. This has created considerable uncertainty in the evolution of subsequent convection today. Recent trends in radar data indicate showers beginning to develop across eastern Nebraska and southwest Iowa, which are not well resolved by current near- term model guidance. As such, we will maintain VFR conditions, but include TEMPO groups for MVFR ceilings and visibility due to thunderstorms this morning. The cold front will stall over northeast Nebraska this afternoon with potentially variable wind directions at KOFK. Specific timing and location of convection east of the front this afternoon into tonight remains highly uncertain, so we will only include PROB30 groups at KOMA and KLNK. We could also see some reduced visibilities in fog later tonight, especially at KOMA and KLNK. && .OAX Watches/Warnings/Advisories... NE...None. IA...None. && $$ SHORT TERM...Pearson LONG TERM...Pearson AVIATION...Mead

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