DES MOINES, Iowa (AP) — With snow still on the ground and spring just a month away concerns that snow melt and spring rain could happen all at once causing flooding are increasing.

State Climatologist Harry Hillaker says Iowa ground remains solidly frozen with frost reaching 33 inches, twice the depth one would expect this time of year. That means any rainfall runs off the ground. He says the later freezing temperatures stay the more likely snowmelt will come as spring rain sets in, which could increase flood chances.

National Weather Service Hydrologist Jeff Zogg says it doesn’t appear all the factors line up for a significant flood event in Iowa, but timing of the spring thaw and rainfall is everything. The weather service releases its spring flood outlook on Thursday.