Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 251121 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 621 AM CDT Sun Jun 25 2017 .SHORT TERM...(Today through Tuesday) Issued at 322 AM CDT Sun Jun 25 2017 Another day or two of pretty mild weather before temperatures rebound back into the 80s on Tuesday. Precipitation chances should be confined to late tonight into Monday, but most likely only a small chance for thunder during that time. Northwest mid level flow continues this morning from western Canada into the central CONUS. Shortwave within this flow was noted in Manitoba and southern Saskatchewan, which is forecast to dive southeast into the Plains today and tonight, ushered southeast by 100kt upper level jet streak. While moisture availability will be fairly low, a good majority of model output continues to paint areas of QPF in eastern Nebraska and western Iowa beginning later tonight into Monday. Our current forecast has mention of showers tonight and Monday morning, so see no reason to remove those given consensus of model output. However rain amounts should remain spotty and light through 18Z. Attendant surface cool front should be settling into southeast Nebraska and southwest Iowa Monday afternoon when and where moisture profiles are a little better and yield minimal instability. Forcing for precipitation will end late Monday afternoon as upper jet streak tracks east and southeast of our area. Then shallow mid level ridging builds into the region ahead of potent shortwave approaching from the west for Tuesday night. Warm advection regime under building ridge may spark convection to our west and north during the day Tuesday where moisture return, instability and surface convergence are maximized. Inhibition should be too much to overcome in our area during the day Tuesday. However with southerly low level flow well under way, noticeable humidity increase will be felt as dew points surge back into the 60s. .LONG TERM...(Tuesday night through Saturday) Issued at 322 AM CDT Sun Jun 25 2017 A more active weather pattern is taking shape for mid and late week. Zonal mid level flow through Wednesday night will buckle as strong shortwave drops into the High Plains on Thursday, placing our area under diffluent flow aloft. Convection chances begin Tuesday night when mid level shortwave rolls out of the Rockies, triggering storms in instability axis under steepening lapse rates over western Nebraska Tuesday afternoon, with that activity moving/spreading east overnight. Low level jet increases to near 50kt as per ECMWF and GFS with ample lower atmospheric moisture in place, suggesting continued progression of MCS across our area overnight. System will likely still be affecting at least the eastern half of the CWA Wednesday morning. Trailing cold front settling into southeast Nebraska and southwest Iowa will offer a focus for afternoon development as well, when pooled moisture near boundary yields MLCAPE potentially over 3000 J/kg in area of 50kt bulk shear. Approaching mid level trough Wednesday night and Thursday may initially trigger convection in northeast Nebraska overnight, but will also draw Wednesday frontal boundary north. Cooling aloft will only help to increase afternoon instability as low level moisture remains in place and bulk shear remains impressive. Severe storms are likely if the above scenario plays out even close to model output, especially Wednesday and Thursday. Lingering storms may affect part of the area on Friday, but by Saturday we should be on back side of mid level trough with rising heights and warmer mid level temperatures keeping a lid on convection. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 614 AM CDT Sun Jun 25 2017 VFR conditions expected thru the fcst pd. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE

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