A tornado has wreaked havoc on a farming station near Gisborne, taking out sheds and injuring at least one farm dog believed to have been picked up and dumped.

Craig Ferris had just finished work at Te Aroha Station at Pehiri, about 35km inland from Gisborne, yesterday, when it struck.

It had been blowing strongly from the southeast, bringing a brief hail shower when he noticed the wind suddenly changing to the northwest.

"The noise was incredible - it was like a massive whirlwind."

When the wind started picking things up around them he "huddled in a ball" in the corner of his carport, watching trees and sheets of iron flying by.

The wind clipped the corner of his home, ripping off part of the scotia and guttering.

It tore through the back yard, down into the valley and up on to the hill beyond, flattening everything in its path, including an old woolshed, and snapping off fence posts in a 4-5km track across the valley.

Mr Ferris later noticed a large 4000 gallon iron water tank on a hill behind his home was not there any more. He thought he saw it flying about 100m in the air, along with other debris.

The hen house was obliterated and the roof ripped from a shed. A garden shed was lifted and dropped several metres away, narrowly missing the house, while a large old oak tree lay uprooted alongside.

The chooks and pigs lost their which were strewn among uprooted and smashed fruit trees.

Next door at the home of his boss Phillip Steele, one dog was not so lucky. He found it struggling to walk.

"He either got hit by something or got picked up and dropped... the vet thinks he has a broken pelvis but he's going to be all right," Mr Steele said.

He was in his workshop when "an almighty wind" came up. When it blew out the windows above his workbench and started tearing off the roof, he sheltered in a corner watching his trailer and a couple of large culverts picked up and tossed across the yard by the wind.

"I have never seen such a strong wind apart from the back of a jet engine," he said.

The wind had come up out of nowhere with very little warning, he said.

Their neighbour Sam Hain arrived back from town to discover the trail of destruction, having to cut broken trees from the road to get through.

He saw Mr Ferris' four wheeler unmanned on a slope above the house, with the trailer upturned not far away.

This morning the men were facing a huge clean-up.

"At least we are going to have plenty of firewood next winter," said Mr Ferris.

The tornado and the hail sprang from the same source - a rapidly moving front loaded with moisture which swept up from the south and collided with cold air over our district.

At the leading edge of the front warm air from ground level is forced rapidly upwards into a freezing layer only a few thousand metres up.

While moisture freezes out as hailstones, the fast-moving front causes the air to swirl and rotate.

While tornadoes are rare in this region, the steep topography of the hill country can amplify air currents and rotating winds can occasionally form a localised and damaging, but usually short-lasting tornado.

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