Act as a Machine Learning Engineer with 10+ years of experience in real estate risk assessment. Your task is to develop a predictive model that evaluates the risk of default on [property type] loans in [specific geographic region]. The model should incorporate features such as [economic indicators], [property-specific data], and [borrower financial history]. Additionally, ensure the model accounts for [seasonal market trends] and [external factors like natural disasters]. Provide a detailed explanation of the algorithm chosen, the rationale behind feature selection, and the validation process. Include a risk score output for each property, ranging from low to high risk. Finally, suggest actionable insights for lenders to mitigate potential risks based on the model's predictions.