Precipitation and moisture flux divergence associated with Great Plains low level jet activity
Five years of NCEP/NCAR Reanalysis specific humdity, u- and v-component winds, and NCEP daily precipitation data have been evaluated to determine moisture flux convergence and precipitation associated with low level jet (LLJ) activity during JJA of 1992 - 1996. Hourly NOAA Profiler Network 404 MHz radar profiler data were used to determine persistent and widespread (PW) LLJ conditions for evaluation. Analysis shows that moisture flux convergence and precipitation during PW LLJs is enhanced over the Great Plains. During PW LLJ events average moisture flux convergence is maximized in the Nebraska-Kansas region, increasing approximately 100% in magnitude from mean JJA values. Average precipitation is also nearly doubled over the Great Plains during PW LLJS, with a dipole structure of anomalous high (low) precipitation over the Great plains (southeast United States). Finally, it is shown that precipitation during PW LLJs is located northeast of the moisture flux convergence maximum.
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