You can download the parent toolkit here and it says:
http://www.nwea.org/support/details.aspx?content=930
Quote
Can parents discuss assessment data directly with NWEA?
Unfortunately due to privacy laws regarding student information (specifically, stemming from Federal Educational Rights and Privacy Act FERPA) we are unable to discuss any student information, test results, or district assessment programs with parents.


The flip side of FERPA is that it also gives you the right to review your child's records including testing.

I would call back the school contact and say "I don't want to wait until fall because the information will help me now as I work with my son to support his learning through the summer. I'll be happy to come in so I can view his results under FERPA."

Hopefully that will be enough. If not, I'd contact the principal followed by the district testing coordinator with the same request. If phone calls don't work, I'd write a letter.