The outlook shows that although the unrestricted ending fund balance in 2015-17 is positive ($264 million), the unrestricted ending fund balance in 2017-19 is negative $714 million. One reason for this is that the policy changes proposed by the governor cost $85 million in 2015-17 and balloon to $473 million in 2017-19.
Note that those figures include the spending and tax changes related to the governor's teacher recruitment and retention proposal. (He proposed it along with his supplemental budget, but they are two distinct proposals.) If you back out these increased spending and taxes, the unrestricted ending fund balance in 2017-19 would be about the same (negative $705 million).
Of course, the governor isn't required to propose a budget that balances over four years. But the Legislature is required to enact a budget that does. One exception is when funds are appropriated from the budget stabilization account. Gov. Inslee's proposal would do so, for fire costs. It remains to be seen if the Legislature will follow suit.