A previous examination of water vapor layers in Project STORM-FEST is extended to include Project STORM-WAVE rawinsonde observations and assess the contribution of layers in these two datasets to atmospheric water transport. The observations indicate that the contribution of these layers to water transport climatology is only a few percent. However the analysis also shows that episodes occur fairly frequently where these layers contribute 20% or more of the horizontal transport. Instances when the layer’s moisture is an important part of the water transport tend to occur for relatively dry soundings. Numerical models that fail to resolve the layers during these episodes may thus miss condensation events leading to cloud formation and precipitation, and also give overly smooth vertical profiles of radiative heating and cooling. The layers thus appear to be important for numerical weather prediction.