Northeast arrives from Hampshire, for whom he has played in all eight four-day matches this season, scoring 358 runs.
But he has not played any cricket for them, first or second-team, since a T20 Blast game on June 9.
The 31-year-old former Kent captain will debut in tomorrow’s Group Three clash with Northamptonshire at Wantage Road (11am) and will also face Lancashire at Emerald Headingley from next Sunday.
He helps to mitigate against the loss of Dawid Malan and Tom Kohler-Cadmore from the last Championship game against Sussex in early June.
Malan is unavailable having left England duty because of personal issues, while Kohler-Cadmore has broken his finger. Will Fraine is also injured, while Jonny Bairstow and Joe Root are with England.
This is Yorkshire’s penultimate Group Three match, and it is second v third in the table.
Lancashire are top with 126 points after eight games, Yorkshire second with 122 and Northants third with 110.
The top two teams go through to the top group in late August and through September to fight for the title.
A win would likely qualify Yorkshire with a game to spare.
A repeat of the thrilling one-run win over Northants at Emerald Headingley in early May would do fine, though opener Adam Lyth joked: “Hopefully it’s not quite as close this time.
“They are two very important games, but we just have to take one day at a time.
“If we play solid cricket, we know we should be on the right end of the results.
“It’s been a while since we’ve played given the T20 stuff, but we’re going really well in red ball cricket. We’re looking forward to going down there.”
Lyth has some happy memories of playing Northamptonshire.
He was involved in the aforementioned one-run win earlier this season and also scored his record-breaking 161 against them in the Vitality Blast in 2017.
And on Yorkshire’s last visit to Wantage Road for a Championship game in 2014, Lyth scored 230 in the second innings as he and Alex Lees put on 375 for the first wicket in a big win which put Yorkshire on course for the first of back-to-back titles.
“I hope I don’t get a duck first innings,” he reflected. “But I’d take 200 second innings, don’t you worry about that. Great memories.”
Lyth is Yorkshire’s leading run-scorer in Championship cricket this season with 629 runs from eight games, including two centuries.
“It’s gone really well for me in red ball this season, and I’m looking forward to getting going again,” he said.
“Hopefully I can put some runs on the board whenever it is – day one or day two – and get the team into a position where we can drive the game forward.
It’s about putting big first-innings totals on the board. If lads get in, they have to be greedy. With the ball in hand, we need to put six balls in the right area for as long as possible. It’s pretty simple stuff.”
Ben Coad, Duanne Olivier and captain Steve Patterson all played second-team cricket against Warwickshire earlier this week, as have the likes of Harry Duke and Jonny Tattersall.
Northants have won three of eight Championship games this season compared to the four wins for Yorkshire and Lancashire.
They drew their last fixture against Kent at Canterbury at the start of last month.
Lyth added: “From what I’ve seen on videos, there’s been some pace and bounce in the pitch (at Wantage Road), and it’s also been a good one.
“They’ve got a good attack. We saw that at our place, but we just scraped the win.”