Why is KOAK's alternate minimum higher than standard?
regarding non-standard alternate minimums -

From the US Terminal Publications, SW-2:
OAKLAND, CA
METROPOLITAN
OAKLAND INTL (OAK) ILS or LOC Rwy 12:

ILS, Category C, 700-2; Category D, 1400-3



If you plan the KOAK ILS RWY12 to Circle to another runway (e.g., RWY30, RWY28L/R, etc.) the published "no approach light" (ceiling/vis) minimums for your approach are:

CAT A/B: 600-1 1/4 (meaning Alternate Minimums are standard, i.e., 600-2, because 600-2 is higher than 600-1 1/4, the published ceiling/vis minimum without approach lights).

CAT C: 700-2 (meaning that this becomes the non-standard minimum because it's higher than the standard alternate minimum of 600-2)

CAT D: 1400-3 (meaning that this becomes the non-standard minimum because it's higher than the standard alternate minimum of 600-2).  Since 1400-3 is VMC, no "without approach light" additive (the 1/4 mile) is applied. 

NOTES:


See inop component table for visibility additive -which is 1/4 mile vis added- when approach lights are considered inop, as required by TERPS when determining alternate minimums.
From 8260.3C, para. 3-4-1 a. (2): PA. For each approach CAT, select the PA’s ceiling and the PA’s visibility (without approach lights). When more than one line of PA minimums is published on the same chart, use the line with the higher HAT..