Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 182016 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 316 PM CDT Sun Mar 18 2018 .SHORT TERM...(Tonight through Wednesday) Issued at 252 PM CDT Sun Mar 18 2018 Mid afternoon on Sunday featured the same persistent low stratus deck across much of the forecast area that has been in place for the past 36+ hrs. However, the southwest edge was eroding with the GOES snow/ice RGB nicely showing some clearing southwest of a Seward to Beatrice line under additional layers of mid and high level clouds. Surface high pressure had shifted off to the east over northern Illinois while surface low pressure was deepening in southeast Colorado this afternoon. Convective cloud elements and a few light reflectivity returns on radar were moving northeast out of northern KS and central NE, seemingly in response to a push of mid level moisture underneath a plume of steep lapse rates. Additional convection was present from north central OK into southeast OK. Water vapor imagery showed a strong short wave trough digging east across the Four Corners region while another lead short wave was crossing western Oklahoma. The OK system was pulling moisture north into the Plains while the Four Corners trough will not only help steer the OK energy toward southeast Nebraska, but will be providing ample forcing for precipitation over Kansas and into Nebraska/Iowa over the next 24 hours or so. Through this evening, as the forcing approaches and mid level moisture increases, expect coverage of convective showers to increase across much of the area with a focus moreso over southeast Nebraska. Forecast soundings (and current satellite trends) suggest that weak instability currently in place will increase through the evening hours over the southern half of the area as that moisture profile deepens immediately under the steep lapse rates. RAP/NAM soundings indicate 200-500 J/kg of MUCAPE and have included thunder through the evening hours. Later tonight, the northeastward surge of moisture is likely to wane and stall as the main upper low crosses the Plains near the KS/OK border. This storm track should actually work to pull dry air into the forecast area from the northeast, and have tapered off to a dry forecast in eastern parts of the forecast area by Monday afternoon. A separate short wave trough on a more northern trajectory comes into play by Monday afternoon through Tuesday as it very slowly moves across the region. Ample moisture pulled from east to west around the north side of the KS/OK storm system will interact with weak to moderate forcing to develop a slow moving band of snow and/or rain from late Monday into Tuesday. While precipitation is likely, the main questions for the forecast at this point lie in the quality of the moisture profile and the specifics of the temperature profile. Currently have a trace to 2 inches of snow in the forecast, but given the expected duration of the snow could see a bit more than that especially in far northern parts of the forecast area if temperatures are cool. This will be something to watch. Any precipitation should end in eastern parts of the forecast area by early Tuesday afternoon with a warming trend through the remainder of the work week. .LONG TERM...(Wednesday night through Sunday) Issued at 252 PM CDT Sun Mar 18 2018 Wednesday and Thursday are expected to be mainly dry as an upper level ridge gradually builds overhead. There is a consistent signal for an area of rain to develop near/northeast of the area Thursday night into Friday in response to warm advection and moisture convergence. Then from Friday through the weekend the weather pattern looks to remain active with the main question being in the timing and track of multiple storm systems expected to cross the Plains within the generally southwesterly upper flow pattern every 48 hours or so. At this point, uncertainty is too great in timing and track to indicate any specific hazards, but it is worth mentioning that impactful weather will be possible through the period in the local forecast area. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1234 PM CDT Sun Mar 18 2018 Widespread IFR or low MVFR cigs will persist through Monday morning. Areas of fog and drizzle are forecast to reduce visibilities into the IFR category at all sites after 02Z this evening and persist through at least 15Z Monday. Areas of rain may develop as well, with visibilities improving briefly in heavier showers. There is also a slight chance for light snow at KOFK 10Z through 18Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Barjenbruch LONG TERM...Barjenbruch AVIATION...Dergan is the U.S. government's official web portal to all federal, state and local government web resources and services.