Peakflow Forecasts Header

GREEN--HOWARD HANSON DAM
   State:  Washington    County:  KING
   Latitude:  47 16' 40" North    Longitude:  121 47' 13" West
   Elevation:  1206 feet
   Supporting WFO:  Seattle    
   Inflow Data  

Forecasts are calculated from a forecast time series that approximates flow at a 6 hour time step interval. Observed instantaneous peaks can be higher than model forecast peaks.

GREEN--HOWARD HANSON DAM   (HHDW1)
Forecasts for Water Year
2026
Ensemble Date: 2026-02-18
Forecast Period: February 18 to June 1
Exceedence
Probability
Inflow
CFS
Probable
Date of Peak
95 % 1950 2026-02-28
90 % 2019 2026-03-01
70 % 2493 2026-03-10
50 % 3068 2026-03-23
30 % 3715 2026-04-15
10 % 5608 2026-05-14
05 % 7094 2026-05-21

Peakflow exceedence plot for HHDW1

 Click to download runoff traces used in forecast.  Click for comma delimited data used in plot.csv icon