YUMA, Ariz. (KYMA) - Happy Mother's Day to all ladies in the Desert Southwest that celebrate! Sunday's temperatures are above average compared to May norms, but all things considered, the weather is holding up to celebrate the holiday properly. Sunday's high temperatures for Yuma and El Centro are rolling in for the late afternoon at about 106°F. Moving into Monday, both cities have an extreme heat warning in effect from 11 a.m. to 8 p.m. Yuma's…