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
2027
Ensemble Date: 2026-10-05
Forecast Period: October 5 to February 1
Exceedence
Probability
Inflow
CFS
Probable
Date of Peak
95 % 1743 2026-11-08
90 % 3079 2026-11-20
70 % 5059 2026-12-14
50 % 7180 2027-01-02
30 % 8231 2027-01-10
10 % 12347 2027-01-26
05 % 22655 2027-01-30

Peakflow exceedence plot for HHDW1

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