The Paralympic discus champion, 24, beat his mark of 15.93m set last year.
Davies threw 16.14m when competing with able-bodied rivals at the British Indoor Championships in February, but that was not ratified by the IPC.
"I'm excited to build on that performance and see what I can produce this year," said Welshman Davies.
His new mark remains an unofficial world record until verified by the IPC.
"The event went well, I came to Arizona for warm-weather training and the competition fitted nicely at the end," said Davies.
"It was my first outdoor meet of the year so it was nice to PB even though I was shaking out the cobwebs.
"I don't compete much as I'm injury-prone - the plan is to get to Rio in one piece."
Davies is set to be named next month among the first phase of Great Britain track and field athletes for the Rio Paralympics.
He is aiming to compete in the shot put after his discus event was removed from the competition.
The Bridgend man, who has limited functionality of his right leg with missing bones and no muscle or ligament growth, took gold in the discus at London 2012 and bronze in the shot and is the current European and world champion in both events.

Asghar Stanikzai hit 101, his first one-day century, to help the Afghans hit their highest ever total of 338 in the Indian venue of Greater Noida.
Ireland opener Paul Stirling was on 95 with them going well on 173-1 when he was given out to a Rashid Khan ball.
Andrew Balbirnie's dismissal to a Dawlat Zadran ball also looked harsh.
Leg-spinner Stirling produced an outstanding individual display as he picked up six Afghanistan wickets.
With Ed Joyce (55) having put on 113 for the first wicket with Stirling and skipper William Porterfield contributing 45, the Irish top order kept the run chase on target.
After Balbirnie's dismissal left Ireland on 228-5 in the 37th over, Stuart Thompson and Gary Wilson put on 50 for the next wicket over the next six overs but they both departed in quick succession to effectively end the contest.
Afghanistan bowler Khan finished with figures of 6-43 with Zadran taking three Irish wickets.
The Afghans beat Ireland in Wednesday's opening one-day game and there are three further contests, beginning with Sunday's game at the same venue.
Ireland had already been whitewashed 3-0 in a Twenty20 series between the sides in India.
The teams will play meet in a further Intercontinental Cup match at the end of the month in Greater Noida.

Katy Bethel, 28, and Aaron Harris, 33, were arrested on 4 July 2015 at Coquelles' Eurotunnel check-in.
The couple were returning from Calais to Folkestone when they were stopped by customs officers after a four-hour trip to France.
Both were charged with aiding and abetting unlawful immigration.
Harris had previously pleaded guilty to the charge.
Ms Bethel, of Dial Road, Gillingham in Kent, appearing at Maidstone Crown Court, denies the charge.
Ms Bethel was six months pregnant with her fourth child when the Mercedes van she was in was stopped for border checks, the jury was told on Thursday.
When Harris was asked to open the van doors a police officer glimpsed a person's legs, and discovered 12 people concealed amongst tyres in the back of the van.
Ms Bethel told the court she had "no idea" the people were in there.
The prosecution questioned why she had previously stated they were going to buy alcohol and cigarettes for a party, but did not return with any purchases on what was a very short day out.
In the four hours the pair were in France, they sent and received 67 messages and voicemails to and from unknown numbers, the court heard.
Ms Bethel said Harris was using her phone on the trip to make calls and texts and she was unaware of their content.
She and Harris, the father of two of her children, were loaned the van from a friend of Harris' for a last minute day trip, the court was told.
They got lost while looking for a beach so instead left the van on a roadside to take an hour-long walk to a strawberry field near Calais, she said.
The prosecution accused Miss Bethel of talking "nonsense".
The case continues.
Reigning world champion Aled Davies has improved his own F42 outdoor shot put world record to 16.13m at the IPC Athletics Grand Prix in Arizona.
[NEXT_CONCEPT]
Ireland were on the receiving end of two controversial lbw decisions as they lost their second one-day international against Afghanistan by 34 runs.
[NEXT_CONCEPT]
A pregnant mother had "no idea" there were 12 Vietnamese migrants in the back of a van she was travelling in, a court heard.