The latest model runs are in and it appears clear now that we have an extraordinary weekend ahead--with the only exception being the northwest WA coast. The trend in model solutions suggest less concern for clouds reducing the highs on Sunday across the western interior.
The latest radar imagery (Friday 9:30 PM) indicates a few shower over SE Washington and that they are dissipating and moving out rapidly.
Tomorrow, as the ridge builds, temperatures will warm up considerably from the temperatures we experienced today: mid to upper 50s in the west and the upper 60s over the basin of eastern Washington.
Lets take a look what we expect. First, lets start with the 4-km run of the UW WRF for 5 PM Saturday...near the time of max temperatures:
PROBCAST, which is based on statistically postprocessing an ensemble of forecasts. PROBCAST is very good with warm temperature situations. Below is Probcast's max temps for Saturday and Sunday. Very similar idea to the WRF runs.
Now the only reason to get nervous about this forecast is that there will be some clouds along the coast that will stretch into southern B.C. Here is the cloud forecast from WRF for 5 PM Sunday: