UTC - Coordinated Universal Time
Weather observations and forecasts are usually reported in UTC, which
used to be known as Greenwich Mean Time (GMT), i.e. the local time at
the Greenwich meridian (zero degrees longitude). This allows weather
observations the world over to have the same time stamp. Since UTC is
ahead of local time in the United States, sometimes weather data will
have tomorrow's date, but it still represents today's data (we are not
THAT good at forecasting the weather).
UTC is 8 hours ahead of Pacific Standard Time (e.g. 0000 UTC is 4
p.m. PST the previous day, 1200 UTC is 4 a.m. PST the same day), 7
hours ahead of Pacific Daylight Time (e.g. 0000 UTC is 5 p.m. PDT the
previous day, 1200 UTC is 5 a.m. PDT the same day).
P.S. it is UTC instead of CUT to make the abbreviation language independent.