Peakflow Forecasts Header

GRANDE RONDE--NEAR PERRY
   State:  Oregon    County:  UNION
   Latitude:  45 21' 15" North    Longitude:  118 11' 29" West
   Elevation:  2950 feet    Gage Datum:  
   Supporting WFO:  Pendleton    
   Action Stage:  5.8'   Flood Stage:  6.6'   Moderate Flood Stage:  7.5'

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.

GRANDE RONDE--NEAR PERRY   (LGNO3)
Forecasts for Water Year 2026
Ensemble Date: 2026-07-20
 Forecast Period: July 20 to November 1
Exceedence
Probability 		Stage
feet 		Discharge
CFS 		Probable
Date of Peak
95 % 0.93 29 2026-08-08
90 % 1.01 38 2026-08-21
70 % 1.15 57 2026-09-25
50 % 1.23 70 2026-10-20
30 % 1.30 83 2026-10-25
10 % 1.69 181 2026-10-30
05 % 1.81 220 2026-10-31

Peakflow exceedence plot for LGNO3

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