A Heavy Freezing Spray Watch is issued by the National Weather Service of the United States when there is an increased risk of a heavy spray event that meets the necessary criteria, but the occurrence, timing, and/or location are still uncertain. A watch will be issued when forecasters expect freezing water droplets to be able to accumulate on sea vessels at rates of 2 cm per hour or greater. This accumulation must be caused by an "appropriate combination of cold water, wind, cold air temperature, and vessel movement."
See also Severe weather terminology (United States)
References
External links National Weather Service