The phrase "surprise increase" is correct and is commonly used in written English.
You can use it to describe a sudden or unexpected rise in something, such as prices, taxes, or interest rates. For example, "The surprise increase in electricity prices has made it difficult for many households to stay within their budget."
Morrisons achieved a surprise increase in sales over Christmas as customers returned to the supermarket chain.
The Swiss bank reported a surprise increase in profit as it benefited from a tax credit.
A surprise increase in loan loss provisions by Toronto-Dominion Bank in June squarely focused attention on the issue.
Oil prices are under pressure again after new figures showing a surprise increase in US crude stocks.
A surprise increase in demand should lead firms to raise prices by less if they expect inflation to be low.
RedEnvelope's approach gives it higher margins, analysts said, but it does not provide flexibility to meet a surprise increase in demand.
They are often unaware of the shortages and may be caught by surprise, increasing the risk of a medical error.
When they looked to see what might explain surprise increases or drops, some began to suspect problems in the allocation of group quarters.
Part of the problem, a spokesman for the railroad said, is that the nation's economic recovery this year caught railroad managers by surprise, increasing demand for all kinds of rail freight, with coal only one competing interest among many.
And while many initiatives were scaled back as Congress and the White House sought to cut the overall cost, there were some surprise increases, including a quadrupling of money for high-speed rail projects to $8 billion.
Legislators might tweak the disclosures so that the lobby filings link to the campaign reports or list the candidates someone worked for (side effects might include — surprise! — increased political profiling, by partisan identification, of lobbyists).
