About High Frequency Voice Broadcast for Offshore Waters
The VOBRA (High Frequency Voice Broadcast provided by the United States Coast Guard) forecast provides
mariners with a general overview of large scale environmental
marine conditions for the next 5 days. The synopsis has a brief description of significant
weather features and forecast over the offshore waters through the forecast period.
Emphasis is placed on the forecast movement of low pressure, high pressure, fronts, and
tropical systems. It covers a smaller area and contains more detailed information than the
High Seas Forecast.
The forecast includes expected winds, seas, reduced visibility, and any precipitation.
Emphasis in the forecast is for systems with maximum sustained winds (over
a ten minute period) in excess of
34 knot (39 mph) and areas with reduced visibility of less than 1 NM. A warning is issued
when wind conditions are expected to exceed 34 knot (39 mph) within a 24 hour period. The
term "Gale" refers to extratropical lows or an area with maximum sustained winds
(averaged over a ten minute period, momentary gusts may be higher) ranging
from 34 knot (39 mph) to 47 knots (54 mph). A "Storm" refers to an extratropical
low or an area with sustained winds (averaged over a ten minute period, momentary gusts may
be higher) of 48 knots (55 mph) or greater. Hurricane Force refers to a
extratropical low or an area of sustained winds (averaged over a ten minute
period, momentary gusts may be higher) in excess of 64 knots or higher(74 mph).
A "Tropical depression" has maximum 1 minute sustained surface wind of less than 34
knots (39 mph). A "Tropical storm" has maximum 1 minute sustained surface wind of 34
knots (39 mph) to 63 knots (73 mph). A "Hurricane" has maximum 1 minute sustained surface
winds 64 knots (74 mph) or greater.
The VOBRA is issued every 6 hours for the Western North Atlantic and
Eastern North Pacific Oceans. It may be issued sooner when current or expected conditions
differ significantly from the forecast.
More information about the VOBRA is available at