The tragic news was confirmed tonight — with tributes describing her as the "best up-and-coming" boarder in the country.
Ellie had recently been training abroad but was in the UK when she died.
Her devastated dad Tony said today: "This cruel world took my Soul mate and 'Bessie' from me yesterday on her 18th birthday.
“I was so proud of the beautiful young woman she had turned into.
"Ellie I will miss you more than you could have ever imagined. Rest in peace you little Champion!”
A memorial will take place at the Hotel Spa Crychar in Les Gets, France on Friday at 6:30pm, he added.
Rising talent Ellie claimed Team GB's only medal at the European Youth Olympic Winter Festival in Erzurum, Turkey last year when she was just 16.
As she secured the podium finish, she said: "I don't think it's quite sunk in yet. I'm a little bit emotional. I cried as I crossed the line."
A specialist in freeride and boardercross, she was due to return to snowboard cross competition next month.
Ellie had been selected to compete for Britain at the Junior World Championships in New Zealand.
A Team GB spokesman said: "The British Olympic Association is saddened to hear of the sudden passing of snowboard cross athlete Ellie Soutter, aged 18.
“Ellie was an incredibly popular and well-liked member of the team.
"Our thoughts are with her family and friends at this sad time."
Ellie's "ultimate goal" was to qualify for the 2022 Winter Olympics in Beijing and was an inaugural member of the British Europa Cup snowboard cross programme
British Ski & Snowboard issued an emotional statement tonight describing her as among the "best" young boarders in the UK.
"British Ski & Snowboard is saddened to hear of the sudden passing of Ellie Soutter, 18.
"Ellie was one of the country’s best up-and-coming snowboarders, competing in both snowboard cross and freeride.
"A bronze medallist in snowboard cross at the 2017 European Youth Olympic Winter Festival in Erzurum, Turkey, Ellie claimed Team GB’s only medal of the event.
"She spent the 2017/18 season competing on the Freeride Junior Tour, but was due to return to snowboard cross competition next month after being selected in the British team for the Junior World Championships in New Zealand.
"She was an inaugural member of the British Europa Cup snowboard cross programme which commenced earlier this year.
"The thoughts and condolences of the British Ski & Snowboard community are with Ellie’s family, friends and teammates."
More to follow…
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