Peakflow Forecasts Header

OKANOGAN--NEAR TONASKET
   State:  Washington    County:  OKANOGAN
   Latitude:  48 37' 57" North    Longitude:  119 27' 28" West
   Elevation:  861 feet
   Supporting WFO:  Spokane    
   Action Stage:  14'   Flood Stage:  15'   Moderate Flood Stage:  17'
   Major Flood Stage:  18'

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.

OKANOGAN--NEAR TONASKET   (TONW1)
Forecasts for Water Year 2026
Ensemble Date: 2026-03-12
 Forecast Period: March 12 to July 1
Exceedence
Probability 		Stage
feet 		Discharge
CFS 		Probable
Date of Peak
95 % 12.21 11977 2026-04-17
90 % 12.35 12253 2026-04-23
70 % 13.34 14400 2026-05-08
50 % 13.94 15758 2026-05-18
30 % 14.73 17616 2026-05-28
10 % 16.15 21210 2026-06-09
05 % 17.06 23659 2026-06-11

Peakflow exceedence plot for TONW1

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