Final.HCI.Report.HDR - Laserfiche WebLink

Home Browse Search

A - December to March Precipitation (single season) District 26 In the northern portions of the basin, District 26 there is only one precipitation station (Saguache) therefore the user is cautioned as to the level of which this stations exhibits actual conditions in the basin as a whole. This is a basin where the HCI values did not reveal any striking relationships with regards to precipitation. The most notable relationship, worth mentioning was with the SOI (an ENSO index) which shows some connection with drier periods with El Nino measured in the summer and early fall but, this degrades as winter and approaches. Overall, there is little significant value presented in this area for this season. District 20 In summary, the key `wintertime' precipitation in the basin has quite a bit of variability that appears to be influenced by Atlantic Ocean -based HCI variables. In District 20, the preliminary results show that HCI's are influenced (in a leading mode) by the North Atlantic Oscillation (NAO) and the Atlantic Multi - Decadal Oscillation (AMO). An example of this relationship can be seen in Figure 4, which shows the relationship of the September to November NAO value. The relationship (see Figure 4) is not a `perfect' relationship by any statistical means however; there are some items to note. One is the notable tendency for `very wet' years (> 120% of normal) to occur in years that the NAO was greater than 0.00 and the lack of `very dry' (< 80% of normal), when the NAO value was greater than 0.00. As a secondary indicator, the AMO has a bit of scatter, when it comes to years when the leading mode value is negative. However, in years when the AMO is in a positive leading mode, there is a notable lack of excessively wet years (say, above 105 -110% of normal) hinting that users may not count on excessive precipitation when such a pattern exists when planning supply scenarios. 9