The woman, Micheline Pierre, suffers from Alzheimer's.
She was waiting for her husband in their car while he shopped inside the B&H store in Midtown.
He was inside for about 30 minutes.
When he came out at about 2 p.m., she was gone.
NYPD Bloodhounds picked up her scent across the street to the main post office, but then lost it.
Given the weather conditions, police are trying to find her as soon as possible.
Pierre is described as a black woman, 5'06" tall, 160 lbs., with black hair and a scar on her forehead.
She was last seen wearing a black winter jacket, grey slacks, black dress socks, brown winter floppy hat, black dress shoes, round gold framed eyeglasses and a beige wool sweater.
She was also wearing a gold bracelet, gold necklace, gold earrings, gold watch and three rings.
Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS (8477).
You can also submit your tips by logging onto the Crime Stoppers website at WWW.NYPDCRIMESTOPPERS.COM or by texting your tips to 274637 (CRIMES) and then entering TIP577.
All calls are strictly confidential.