The promising Blues midfielder is at Westleigh Park on loan for the remainder of the season.
He made his National League South bow on Saturday, coming off the bench for the final 11 minutes against Billericay.
Hailing from Hayling Island, the 17-year-old is a boyhood Pompey fan and eager to remain at Fratton Park.
And Cowley believes the youngster’s Hawks spell will help determine whether he achieves that goal.
The Blues’ head coach told The News: ‘Paul Doswell is someone we know well. Harry needs to play and it will test him.
‘I want him to play games, to gain experience of senior football, it’s a really important part of his development.
‘Absolutely this will help decide whether he has a Pompey future. It’s going to be really interesting to see how he progresses, we are definitely open-minded.
‘It’s a local team, so we can keep good tabs on how he is doing. Harry will still train with us on certain days, it will be good for him.
‘There’s Harvey Hughes and Dan Gifford as well, this is an important part of all their development. The challenge is firstly to get into the team, then to find a consistent level of performance.
‘Professional contracts are hard to come by and hard to achieve, the players have to earn them.’
Jewitt-White’s second-year scholar team-mates Hughes and Gifford are presently on loan at the Rocks.
Gifford netted his second goal for Jack Pearce’s side in Saturday’s 2-0 success over Potters Bar, with Hughes also starting.
And Cowley is looking for Jewitt-White to make a similar positive impact at Westleigh Park.
He added: ‘I have managed at step six, I know the quality of that level of football, Havant are a team trying to fight at the top end of that division.
‘It will be really interesting to see how Harry copes with the demands of that level and the challenge of trying to force his way into what is a good Havant team.
‘There were other clubs keen to take him, so it was just trying to find the right pathway for him.’
A message from the Editor, Mark Waldron
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