Peak Day of IWVF for JJAS

To provide a prospective on the time-series of IWVF over the JJAS 'season,' a figure showing the day of maximum IWVF (daily average for 28 years) is shown.
Days are broken down as follows:
June: 1-30
July: 31-61
August: 62-92
September:93-122

The data shows that for the region most associated with NAM surge precipitation, i.e., AZ, western NM, southern UT and NV, and southwestern CO, the peak occurence of IWVF typically falls later in the season between mid-August and mid-September. Our data has been pointing towards this fact, but it is still striking to see how much of the region is dominated by later-season IWVF than most previous research has accounted for. What I am specifically revering to is that most NAM surge research is limited to only July and August analysis, thereby ignoring the vast majority of IWVF events, and most likely surge events, that are taking place.

To back up this point, draw your attention to the Yuma, AZ location (extreme southwestern AZ; Data point where most previous research bases 'surge event' definitions on). The peak for this region appears around day 70 (early August). So, if data analysis were limited to this region a season of only July and August observations might make sense. But, as data points out over the larger domain, this is merely an artifact of where you gather data, not actually physical manifestations for the region.

There are some swearly data areas where very early season peaks are shown directly adjacent to very late season peaks, e.g., northern Mexico. I believe this is an indication of regions with little variability in IWVF amounts during the period analyzed, therefore, resulting in drastic changes in date but not necesarrily amounts.

-jamie