In Milrad et al. (2014), it should be clarified that the “cold conveyor belt” of extratropical cyclones was intended to refer to a region and not a process. A more precise term is “comma head” so as to indicate the specific location within the extratropical cyclone to which we are referring. As Schultz (2001) pointed out, it is actually the warm conveyor belt that is associated with ascent and therefore banded precipitation in the comma-head region of extratropical cyclones.
In addition, we note that the frontogenesis definition presented in Eq. (1) of Milrad et al. (2014) was originally formulated by Petterssen (1936), to which paper Keyser et al. (1988) later refer in the derivation of the Q-vector components. Also, with regard to ingredients-based methodologies, the comments of Schultz et al. (2002) should be considered by the reader, especially in the context of Wetzel and Martin (2001).
REFERENCES
Keyser, D., Reeder M. J. , and Reed R. J. , 1988: A generalization of Petterssen’s frontogenesis function and its relation to the forcing of vertical motion. Mon. Wea. Rev., 116, 762–780, doi:10.1175/1520-0493(1988)116<0762:AGOPFF>2.0.CO;2.
Milrad, S. M., Gyakum J. R. , Lombardo K. , and Atallah E. H. , 2014: On the dynamics, thermodynamics, and forecast model evaluation of two snow burst events in southern Alberta. Wea. Forecasting, 29, 725–749, doi:10.1175/WAF-D-13-00099.1.
Petterssen, S., 1936: Contribution to the theory of frontogenesis. Geophys. Publ., 11 (6), 1–27.
Schultz, D. M., 2001: Reexamining the cold conveyor belt. Mon. Wea. Rev., 129, 2205–2225, doi:10.1175/1520-0493(2001)129<2205:RTCCB>2.0.CO;2.
Schultz, D. M., Cortinas J. V. Jr., and Doswell C. A. III, 2002: Comments on “An operational ingredients-based methodology for forecasting midlatitude winter season precipitation.” Wea. Forecasting, 17, 160–167, doi:10.1175/1520-0434(2002)017<0160:COAOIB>2.0.CO;2.
Wetzel, S. W., and Martin J. E. , 2001: An operational ingredients-based methodology for forecasting midlatitude winter season precipitation. Wea. Forecasting, 16, 156–167, doi:10.1175/1520-0434(2001)016<0156:AOIBMF>2.0.CO;2.
