The phrase "a sudden upward" is correct and usable in written English.
It can be used to describe a quick or unexpected increase in something, such as movement, emotion, or statistics.
Example: "The stock market experienced a sudden upward shift after the announcement of the new policy."
Alternatives: "a rapid increase" or "a swift rise".
Even older players at the Roar have seen their careers take a sudden upward trajectory.
Given the subprime mortgage mess and shrinking newspaper readership, the prospects of a sudden upward spike in my financial fortunes after the New Year seemed dim.
America may be the issuer of the world's reserve currency, but its debt markets are not immune to a sudden upward lurch, which in turn could threaten the fragile recovery.Governments could, and should, minimise this volatility.
Even the presentation of the show, now that it's been wrestled away from the monotonous uncanny valley of the Brian Dowling era and placed in the exceptionally capable hands of Emma Willis, has taken a sudden upward turn.
Quicksand occurs when a static body of watery sand is disturbed by intense vibration or a sudden, upward flow of water, causing the grains to lift away from one another.
Such an abrupt change from stable coral growth to death and a sudden upward and inshore shift of a reef could happen only because of a sudden change in sea level, he said.
If you plot the share of the vote Trump received in each state on a graph, it resembles a step function with a sudden lunge upward after Wisconsin, rather than a smooth upward projection.
That's why this reported increase was both a sudden leap upward and the result of several long-term, slow-moving trends.
Along with the sharp decline in jobs during December, total hours worked plummeted 1.1%, in large part due to a sudden spike upward in the number of workers who want to work full-time but who can only find part-time jobs.
The cadences are still the same, the sharp breaths between clauses, the sudden upward soaring of the sentence, ensuring the last word ends on a high note.
But sudden upward movements can also occur more quickly.
