What a coincidence; I'm leaving in an hour for that same trip. Three days up EC to WL, then the PCT down to Cascade Locks, and the Gorge trail back to the car at EC. Three days and two nights, just me and my favorite hiking partner......my wife. Temps are predicted to be in the low 70's, lows in the 50's with a 20% chance of rain.
For weather, open MSN.com. In the lower left, see the LOCAL tab - it should show the weather for your location. CHANGE that to Cascade Locks, OR. Look at the 10 day forecast. Right now for the 20th, it shows a high of 82° and a low of 56°. Expect that to change.
We tried the same hike 2 weeks ago. Snow across trail started at 3700' about 1/2 mile below Wahtum Lake. Almost solid snow at the lake. Couldn't find a way up the Wahtum Express to the PCT due to snow under the trees, so retraced our steps. It should be a lot different today.
Stay tuned. I'll give you a report when I return. Also check out the trip reports section on the Portland Hikers Forum http://www.portlandhikers.org/forum