If you look at historical El Nino cases, there is a lean toward wetter conditions for southern CA region.  With that said keep in mind that ENSO has its greatest relationships with the seasonal (3month) average, so you can even have dry weeks even while the season as a whole is wetter than average.    Palm Springs has a bit of a rain shadow effect too (I believe) with the mountains located right there, so it's possible that its not as sensitive to El Nino as more coastal regions.  I'm not entirely sure so you may want to contact a local weather expert.