Mr Penny believed whole milk powder prices might have further to go and might challenge $US4000 per metric tonne in the new year.
"In particular, we expect the data on New Zealand and European Union production are set to get worse before they get better.
"For example, we expect New Zealand production to fall 5% over the season as a whole from the 3.1% decline for the season to date.
"Also, we expect flat production in the EU this calendar year, which is less than official EU forecasts of a small rise," he said.
Westpac senior economist Anne Boniface said interest from China appeared to have been a little softer in this week's auction,, following strong interest in the last couple of auctions.
However, buyers from other regions appeared to have taken the opportunity to "fill the gaps", providing ongoing support for prices.
Westpac yesterday bumped up its forecast to $6.20 which should be well above break-even levels for most farmers, Ms Boniface said.
BNZ lifted its forecast to $6.40 and economist Doug Steel said the milk price could well end up higher than that if global milk supply continued to contract more than anticipated - or lower if production held up. Demand would also play its part.
Fonterra holds its annual meeting at its Darfield site today.