Simplify the following text for a Grade 10 native English-speaking person.
Original: Grace continued to organize and intensify ; based on satellite intensity estimates and reconnaissance reports , the storm was upgraded to a Category 1 hurricane , the lowest level on the Saffir Simpson Hurricane Scale .
Simplified: Based on satellite estimates of the storm 's intensity and reconnaissance reports , it was upgraded to a Category 1 hurricane . This is the lowest level on the Saffir-Simpson Hurricane Scale .