The Salvation Army doesn't know exactly when or where Hurricane Harvey is going to hit, but either way, relief workers are getting their canteen truck ready if they need it.

"This is a mobile feeding unit capable of feeding hundreds of people a day, three meals a day and we can do it for days at a time; possibly even weeks at a time if the damage is really severe," Brad Mayhar from the Salvation Army San Antonio Area command.

The last time the Salvation Army used its mobile feeding unit in San Antonio was in February when multiple tornadoes hit the area.

"We'll serve meals, to not just first responders and volunteers that are on the ground, but we'll also be there to serve the victims themselves, the residents who are displaced," he said.

The Red Cross is mobilizing its volunteer base to man shelters set up by the city, if it gets to that point. They'll be ready for potential evacuees from the coast and area neighborhoods that could get flooded.

In the hours leading up to the storm, the Red Cross urges people to be prepared.

"Get yourself a backpack, and get enough for each of your family members. Put enough in there for three days. You're going to want to have flashlights with batteries. If you're on any medication, make a stash of that to take with you in your emergency bag as well, because you're definitely going to need that if you do have to evacuate," said Libby Castillo from the American Red Cross in San Antonio.

For evacuation maps, safe routes and to find emergency shelters and special services in your area download the Red Cross' app. Also get the latest weather updates to your phone through the KENS 5 mobile app in case you lose power.

You can find updated information for the Bexar County area about emergency shelters, weather warnings and advisories on the Red Cross' Facebook page.

If you want to help people directly affected by Hurricane Harvey, you can visit the Salvation Army's website or call 1-800-SAL-ARMY.

If you'd like to volunteer with the Salvation Army locally, call (210)-352-2000.

Other helpful sites for disaster information include the following: