Astronaut Snoopy might not be cleared for take off. The usually buoyant SpongeBob SquarePants may wind up deflated and depressed. Olaf, the garrulous snowman from “Frozen,” could find himself melting into a heaping puddle on the pavement.

That’s because though New York City plays Thanksgiving host to the annual Macy’s parade, it has a strict and specific set of balloon-flight regulations that have been in place since 1997, when a windswept inflatable Cat in the Hat caused destruction that left one woman in a coma for nearly a month.

So as omnipresent as the mammoth character balloons are, so, too, are weather forecasters, police officers and others trying to guess which way the wind will blow.

[Live updates: Before Thanksgiving, travel disruptions spanned the U.S. on Wednesday.]

Macy’s has a licensed meteorologist — armed with a laptop and an open line to the National Weather Service — on hand every year to observe weather conditions, monitor gusts and help make decisions about the floating characters in the procession.