June 2018

Hydrologic condition
Condition period start
Condition period end

To set the hydrologic condition for June, an index of conditions is computed using four Platte basin variables. These variables and their corresponding values were as follows:

  1. The mean May streamflow in the Platte River at Grand Island was 1,883 cfs (provisional data), or at the 62.6 percentile level of 1947-1994 April flows.
  2. The mean May Palmer Drought Severity Index for four zones (NCDC climate divisions Colorado #1, Wyoming #8, and Nebraska #1 and #7) was 2.13* equivalent to the 81.7 percentile level of 1947-1994 May conditions.
  3. The mean May streamflow in the South Platte River at Julesburg (CO-NE stateline) was 412 cfs (provisional data), equivalent to 59.9 percentile of 1947-1994 May flows.
  4. The April 1 percent-of-normal snowpack in the North Platte Basin of Wyoming* (seven specific NRCS locations) was 101.4% of normal, equivalent to the 58.3 percentile level of 1947-1994 conditions. 
Hydrologic Conditions Calculation
Hydrologic Conditions Index = (0.648 * 0.626) + (0.121 * 0.817) + (0.023 * 0.599) + (0.082 * 0.583) + 0.097
Hydrologic Conditions Index

For this period, the threshold index value is 0.30 for "normal" conditions and 0.70 for "wet" conditions. The current index value is greater than 0.30 and less than 0.70 and constitutes "???" conditions.

*based on temporary weekly PDSI data, to be updated when monthly PDSI data is available.