GPA: 4.30 (weighted)
SATs: 2160 (taking them again in May)
Taking Subject Tests in Math 2 and Chemistry at the end of this year.
9 APs: Bio, Chem, Music Theory, Comp Sci, English, AB Calc, Go Po, Macro, Physics
ECs:
Won 2 international music competitions and played solo piano at Carnegie Hall twice
Accepted to all-state for piano
Works at Columbia University Medical Center for internship for two full summers
Founded club which members go to local nursing homes to perform for the elderly
Editor-in-chief of Jazz Band
Pianist in jazz band
Performed for New York Philharmonic
Tennis for four years of high school
Please chance me at Columbia and Northwestern. If you have any suggestions regarding test scores, planning, or anything at all, please let me know 
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Get a 2300+ on the May, SAT, with good scores on each section. Your music awards are outstanding, and with the basic stats you should be good. Btw, what is your UW GPA and approximate class rank?
My school does not give class rank or UW GPA.
Try calculating UW yourself: 4 points for an A, 3 points for a B
3.74 approx (but all honors and AP courses)
Try to pull to at least 3.85 by the time you are applying to colleges. The most important thing is to be in the top 10% of the graduating class, and I think the music will do the rest for you. I would recommend Columbia ED.
Your extracurriculars are great & GPA is competitive, but your SAT scores will need some serious work if you want to be a competitive applicant at either school. Heavy AP courseload is a huge plus - try not to let it drag down your GPA too much if you can. What’s your prospective major? Any major awards? Volunteer work? Try to pursue EC’s related to your future major if possible. You’re a great applicant, but remember that both schools turn down thousands of people more qualified than you each year - try not to set your heart on any one or two colleges and you’ll come out of the application process on top. Good luck!!
Chance back? 
http://talk.qa.collegeconfidential.com/what-my-chances/1751707-chances-for-yale-tufts-wesleyan.html?new=1
For NU you’re maybe competitive if you applied to Bienen given your musical talent, to all the other schools at NU I’d say your chances aren’t impossible but low. I don’t know about Columbia so I can’t judge but generally they have an even lower acceptance rate. Your GPA and test scores are a little low for RD, but a good essay might balance your profile out. Are you a Junior or Senior? As puzzled123 said, if you’re a junior try to improve test scores and GPA and consider ED for your favorite school to greatly improve your chances; If you’re a Senior, your stats are ok but your probably only competitive if you applied to a music school and showed a lot of interest in your essays.