English to Spanish Science Ships, Sailing, Maritime Naval Form Terminology

Hello everyone,

Context: A form where a ship´s information is written down. In this item in particular, they describe weather conditions. I see these must be standard naval terms in English but can´t find the official one for Spanish.

The term (in quotation marks):
Weather symbols:
"OVC"

My try:
I have no clue. Was thinking of leaving it as it is.

Thank you for any help.