Mortgage loan company Fannie Mae (FNMA) said 36,583 single-family homes whose mortgages it covers were in the initial impact area of Tropical Storm Harvey, making it the most powerful storm to hit Texas in the last 50 years, Reuters reports.

The affected homes in Harvey's path have about $5.1 billion in outstanding principal balance.

"While the situation on the ground remains uncertain, areas impacted are subject to change. Based on the rainfall totals and flooding reports we are expanding this impact zone," Fannie Mae said.

Fannie Mae's disaster relief guidelines allow a mortgage provider to delay or lower a homeowner's mortgage payments for up to 90 days if it holds that the natural disaster has negatively impacted the value and livability of the property.

More of What's Trending on TheStreet: