Sylvan Island chance of flooding this year

[Vibrato]

The river level predictions are just out- these are difficult because the gauges are placed just upstream of the locks, so this graph shows the upstream end of the islands water levels. We usually have water problems on the downstream end, and the gauge for this pool is near Muscatine (the two levels around the island are about 6-10 ft different due to the locks and the generating stations.)

This looks like we've got a 100% chance of hitting 15ft AT SOME TIME this spring- not necessarily on race day. 15 ft in the lower pool usually is just creeping up on the lime path on the downstream edge of the island and makes good use of the little bridge next to the sharp hill.

For reference, the top of the concrete next to the entrance bridge on the island side is 21.8 ft and it looks like we've got a 50% chance of hitting that one.

The blue line is historical, the black one is the statistical probability for this spring based on snow melt, ground water and moisture levels, etc. frankly- it ain't lookin good...

Check it for yourself here:http://water.weather.gov/ahps2/perio...0,7,8,2,9,15,6

[Vibrato]

Also, if you want to keep an eye on the actual river level and 48 hour predictions, you can do that here:

http://water.weather.gov/ahps2/hydrograph.php?wfo=dvn&gage=rcki2&view=1,1,1,1,1,1 ,1,1"

[Vibrato]

New forecast is out based on average rainfalls and tempuratures for the springtime, along with the expected snow melt and existing groundwater levels as found on 2/28/11. There is now a 100% chance the river will see 17 ft, and a 70% chance that it will exceed the all time record set in 1993.

This does not mean it will flood the day of the race, but that it will get this high at some point in the next 90 days.

http://water.weather.gov/ahps2/perio...0,7,8,2,9,15,6

[BD83]

Are you saying we should break out the floaties?

[Vibrato]

I hate this cold weather, but it may be saving our race on Sylvan!! If it holds out till about next Wednesday and we don’t get any LARGE rain events- its looking like we might be able to have the race as normal!

River is supposed to hit the 1st peak this Friday/Saturday at about 16 ft and then level off or maybe even drop a little bit. By this Sunday, NOAA should have the forecast for next Sunday up so we can remove what questions there are about it and move forward with a little more confidence.

1st time as a Mountian Biker I'm glad its cold as heck. About every 3 days of cold dry weather they drop the overall peak again. This is working out really good, I hope it keeps up!

[dirtboy]

Good News Ray! Let's hope Mother Nature doesn't harsh our mellow. You sounded good on NPR last night. Almost like an expert But, like you paraphrased " there are things we know, things we don't know, and things we don't know we don't know" or something like that. I'll keep a good thought. db

[Neiprider]

was on the island tonight and the water is over the crushed stone path on the back where it runs along the river. we can always have a river crossing in the race.