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NF STILLAGUAMISH--NEAR ARLINGTON
   State:  Washington    County:  SNOHOMISH
   Latitude:  48 15' 38" North    Longitude:  122 2' 51" West
   Elevation:  89 feet
   Supporting WFO:  Seattle    
   Action Stage:  10.7'   Flood Stage:  13'   Moderate Flood Stage:  14'
   Major Flood Stage:  15'

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.

NF STILLAGUAMISH--NEAR ARLINGTON   (ARGW1)
Forecasts for Water Year 2026
Ensemble Date: 2026-09-10
 Forecast Period: September 10 to January 1
Exceedence
Probability 		Stage
feet 		Discharge
CFS 		Probable
Date of Peak
95 % 6.02 6321 2026-10-18
90 % 7.71 9530 2026-10-28
70 % 9.51 13494 2026-11-12
50 % 9.92 14488 2026-11-23
30 % 11.21 17723 2026-12-07
10 % 14.29 26519 2026-12-19
05 % 15.91 38509 2026-12-22

Peakflow exceedence plot for ARGW1

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