Hey OP, dont bother with yellow bulbs: there isnt a selective yellow bulb on the market wirth anything, and neither LED or HID ("3000K" burners) offer the same spectrum and effectiveness of a selective yellow halogen bulb (or halogen bulb in a selective yellow tinted housing/lens.
Buy a can of duplicolor metalcast gold, a few (1-3 very thin) light/thin layers over the lens of your fog lights, and use the correct type of uncoated (no blue coating, especially) halogen bulb in the housing.
(Selective yellow = incandescent spectrum with blue and cyan wavelengths filtered out [smallest quantity of light produced by an incandescent bulb]. Blue and cyan are the first wavelengths to scatter in dust/ fog/sleet/snow/rain, and are the least useful for seeing, considering most things are brown/red/green/black. You notice alot of offrosd lights, especially led bars are offered with an amber option? They are trying to do the same thing as selective yellow, but LEDs produce mainly blue light, so they cant do that effectively. Amber is the result of filtering blue, cyan and *green* wavelengths from the emitted spectrum).