The LH surge happens in preparation for ovulation. Once the LH surge is over, you will not get positive OPKs any more, and you may or may not ovulate. Chances are that you will ovulate within a day or two of the positive OPK, but since it's just your body's preparation for ovulation, it's not a sure thing, and it is possible that you might not ovulate. The LH surge can be detectable by OPKs for a whole day or two, or for some women it happens between taking tests and is never detectable.
Since you got a positive yesterday, you may or may not get another positive today. Since ovulation happens after the LH surge, you probably won't get another positive after you ovulate. Estimate ovulation to occur a day or two after your last positive OPK.
at 10:59 AM on Dec. 28, 2010