Hope Solo ain't outta the woods yet in her domestic violence case ... because prosecutors have filed an appeal claiming there were significant "issues" with the judge's decision to dismiss the case.
TMZ Sports has learned ... the prosecutor's office for the City of Kirkland in Washington filed the appeal earlier this month.
As we previously reported, Solo was accused of beating the crap out of her 17-year-old nephew and her own half-sister during an alleged drunken rampage in 2014.
Solo denied any wrongdoing ... and a judge threw out the case in January, citing lack of cooperation from witnesses.
But we spoke with Solo's half-sister Teresa Obert -- who says BS ... telling TMZ Sports they were fully cooperative from the beginning.
Obert also says her story has remained the same from the beginning ... and insists Solo was LYING when she claimed she was the real victim.
"She slammed my son's head into the concrete multiple times, punching me repeatedly when I pulled her off of him," Teresa says ... "We tried to keep her away, but she kept coming back into the house. We've never changed our story."
Sources from the prosecutor's office tell TMZ Sports it's NOT standard operating procedure to appeal every D.V. case that's dismissed -- only in cases where "we believe there are issues."
Officials would not tell us what those "issues" are.
Don't expect a ruling on the appeal any time soon ... these things usually take a while.