Peakflow Forecasts Header

JOHNSON CREEK--AT SYCAMORE
   State:  Oregon    County:  MULTNOMAH
   Latitude:  45 28' 40" North    Longitude:  122 30' 24" West
   Elevation:  228 feet
   Supporting WFO:  Portland    
   Action Stage:  10'   Flood Stage:  11'   Moderate Flood Stage:  13'
   Major Flood Stage:  14'

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.

JOHNSON CREEK--AT SYCAMORE   (SYCO3)
Forecasts for Water Year 2026
Ensemble Date: 2026-06-14
 Forecast Period: June 14 to October 1
Exceedence
Probability 		Stage
feet 		Discharge
CFS 		Probable
Date of Peak
95 % 1.44 8 2026-06-28
90 % 1.53 11 2026-07-13
70 % 1.74 19 2026-08-29
50 % 1.88 25 2026-09-15
30 % 1.94 28 2026-09-20
10 % 2.23 43 2026-09-29
05 % 2.78 78 2026-10-01

Peakflow exceedence plot for SYCO3

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