so i think i figured it out.... and didnt take any where near as long as i expected. boy i love the interwebs.
http://serc.carleton.edu/eet/phytoplankton/primer.html
if ya realllly dont want to read all the info on there... (which i strongly recommend you do) it says...
plankton blooms are pretty much almost impossible to predict. but occur in the spring. due to more sunlight, changing water temps that stabilize the water column (which is in turmoil in the winter) and fresh high nutrient filled water (thanks to the winter turmoil)
i dont think its any coincidence that it just so happens when the bait fish start showing up in masses...
so now thats my final answer... the striped ones show up shortly after the bait fish show up, after the first major plankton bloom of year. which happens completely randomly and is determined by a whole crap load of factors.
so ya just don't know unless yer out there fishing so get at it.
(btw just found some real time chlorophyll images... the blooms already started)