Relativistic and ponderomotive self-channeling of intense ultrashort laser pulses in underdense plasmas is investigated numerically under more realistic experimental conditions. The optimization of the controlled power compression and stability of the channel can be realized with the use of appropriate incident laser power, beam focusing, and gas density profile conditions. The results of simulating the whole self-channeling are in good general agreement with the experimental observations for the self-channeling of TW-level 248 nm laser pulses in Xenon gas jets, capture the salient features of the relativistic self-channeling dynamics, and examine the root causes of experimental observations more accurately than before. The channel length is consistent with some transverse Xenon M-shell radiation measurements of the interaction region. The theoretically predicted ∼400 nm channel diameter indicates that the laser channel intensity could be an order of magnitude larger than previously anticipated.