Definitions of Marine Watches/Warnings
Explanation of Warnings
Small Craft Advisory (SCA):
An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO)
for areas included in the Coastal Waters Forecast or Nearshore Marine
Forecast (NSH) products. Thresholds governing the issuance of small
craft advisories are specific to geographic areas. A Small Craft
Advisory may also be issued when sea or lake ice exists that could be
hazardous to small boats. There is no precise definition of a small
craft. Any vessel that may be adversely affected by Small Craft Advisory
criteria should be considered a small craft. Other considerations
include the experience of the vessel operator, and the type, overall
size, and seaworthiness of the vessel.
Eastern (ME..SC, Lake Erie, Lake Ontario) - Sustained
winds or frequent gusts ranging between 25 and 33 knots (except 20 to 25
knots, lower threshold area dependent, to 33 knots for harbors, bays,
etc.) and/or seas or waves 5 to 7 feet and greater, area dependent.
Central (MN..OH) - Sustained winds or frequent gusts
(on the Great Lakes) between 22 and 33 knots inclusive, and/or seas or
waves greater than 4 feet.
Southern (GA..TX and Caribbean) - Sustained winds of
20 to 33 knots, and/or forecast seas 7 feet or greater that are expected
for more than 2 hours.
Western (WA..CA) - Sustained winds of 21 to 33 knots,
and/or wave heights exceeding 10 feet (or wave steepness values
exceeding local thresholds).
Alaska (AK) - Sustained winds or frequent gusts of 23
to 33 knots. A small craft advisory for rough seas may be issued for
sea/wave conditions deemed locally significant, based on user needs, and
should be no lower than 8 feet.
Pacific (HI, Guam, etc) - Sustained winds 25 knots or
greater and seas 10 feet or greater; except in Guam and the northern
Mariana Islands where it is sustained winds 22 to 33 knots and/or
combined seas of 10 feet or greater.
"Frequent gusts"are typically long duration conditions
(greater than 2 hours).
BRISK WIND ADVISORY:
A Small Craft Advisory issued for ice-covered waters.
GALE WARNING: A
warning of sustained surface winds, or frequent gusts, in the range of
34 knots (39 mph) to 47 knots (54 mph) inclusive, either predicted or
occurring, and not directly associated with a tropical cyclone.
STORM WARNING:
A warning of sustained surface winds, or frequent gusts, in the range of
48 knots (55 mph) to 63 knots (73 mph) inclusive, either predicted or
occurring, and not directly associated with a tropical cyclone.
TROPICAL STORM WARNING:
An announcement that tropical storm conditions (sustained winds of 39 to
73 mph) are expected somewhere within the specified coastal area within
36 hours.
HURRICANE FORCE WIND WARNING:
A warning for sustained winds, or frequent gusts, of 64 knots (74 mph)
or greater, either predicted or occurring, and not directly associated
with a tropical cyclone.
HURRICANE WARNING:
An announcement that hurricane conditions (sustained
winds of 74 mph or higher) are expected somewhere within the specified
coastal area. Because hurricane preparedness activities become difficult
once winds reach tropical storm force, the hurricane warning is issued
36 hours in advance of the anticipated onset of tropical-storm-force
winds.
Other Advisories, Watches and Warnings for Marine Areas:
Ashfall Advisory: An advisory issued
for conditions associated with airborne ash plume resulting in ongoing
deposition at the surface. Ashfall may originate directly from a
volcanic eruption, or indirectly by wind suspending the ash.
Beach Hazards Statement: Informs
beachgoers and local authorities to a multitude of hazards including,
but not limited to, the following: rip currents (or other types of
dangerous currents in the surf zone), unusually cold water temperatures,
potential for lightning along the beach/shoreline, or unusual surf/wave
conditions which do not meet advisory criteria. In coordination with
other agencies (as needed), the product may also inform users of various
types of environmental hazards (e.g. chemical spills, harmful algal
blooms, high bacteria levels in the water, or potentially hazardous
marine wildlife which may be impacting the area). It is used to describe
hazards that do not meet NWS advisory, watch, or warning criteria, as
well as hazards that do not have advisory, watch, or warning criteria
(e.g. rip currents, oil spills). The statement is issued using the
Coastal Hazard Message.
Coastal/Lakeshore Flood Advisory:
Flooding is possible (i.e, over and above normal
high tide levels. Coastal/Lakeshore Flood Advisories are issued using
the Coastal and Lakeshore Hazard Message (CFW) product.
Coastal/Lakeshore Flood Watch:
Flooding with significant impacts is possible.
Coastal/Lakeshore Flood Watches are issued using the Coastal and
Lakeshore Hazard Message (CFW) product.
Coastal/Lakeshore Flood Warning:
Flooding that will pose a serious threat to life
and property is occurring, imminent or highly likely. Coastal/Lakeshore
Flood Warnings are issued using the Coastal and Lakeshore Hazard Message
(CFW) product.
Dense Fog Advisory:
An advisory for widespread or localized fog reducing
visibility to regionally or locally defined limitations not to exceed 1
nautical mile.
Dense Smoke Advisory:
A marine advisory for widespread or localized smoke
reducing visibility to regionally or locally defined limitations not to
exceed 1 nautical mile.
Freezing Spray Advisory:
An advisory for an accumulation of freezing water
droplets on a vessel at a rate of less than 2 centimeters (cm) per hour
caused by some appropriate combination of cold water, wind, cold air
temperature, and vessel movement.
Gale Watch: A
watch for an increased risk of a gale force wind event for sustained
surface winds, or frequent gusts, of 34 knots (39 mph) to 47 knots (54
mph), but its occurrence, location,and/or timing is still uncertain.
Hazardous Seas Warning:
A warning for wave heights and/or wave steepness values
meeting or exceeding locally defined warning criteria.
Hazardous Seas Watch:
A watch for an increased risk of a hazardous seas warning
event to meet Hazardous Seas Warning criteria but its occurrence,
location, and/or timing is still uncertain.
Heavy Freezing Spray Warning:
A warning for an accumulation of freezing water droplets
on a vessel at a rate of 2 cm per hour or greater caused by some
appropriate combination of cold water, wind, cold air temperature, and
vessel movement.
Heavy Freezing Spray Watch:
A watch for an increased risk of a heavy freezing spray
event to meet Heavy Freezing Spray Warning criteria but its occurrence,
location, and/or timing is still uncertain.
High Surf Advisory:
. A High Surf Advisory is issued when breaking wave
action poses a threat to life and property within the surf zone. High
surf criteria varies by region. High Surf Advisories are issued using
the Coastal Hazard Message (CFW) product.
High Surf Warning:
A High Surf Warning is issued when breaking wave action
results in an especially heightened threat to life and property within
the surf zone. High surf criteria varies by region. High Surf Warnings
are issued using the Coastal and Lakeshore Hazard Message (CFW) product.
Hurricane Force Wind Watch:
A watch for an increased risk of a hurricane force wind event for
sustained surface winds, or frequent gusts, of 34 knots 64 knots (74
mph) or greater, but its occurrence, location, and/or timing is still
uncertain.
Hurricane Watch:
An announcement that hurricane conditions (sustained winds of 74 mph or
higher) are possible within the specified coastal area. Because
hurricane preparedness activities become difficult once winds reach
tropical storm force, the hurricane watch is issued 48 hours in advance
of the anticipated onset of tropical-storm-force winds.
Low Water Advisory:
An advisory to describe water levels which are
significantly below average levels over the Great Lakes, coastal marine
zones, and any tidal marine area, waterway, or river inlet within or
adjacent to a marine zone that would potentially be impacted by low
water conditions creating a hazard to navigation.
Rip Current Statement: Informs beachgoers
and local authorities of a high threat of rip currents due to weather
and ocean conditions. The statement usually contains some detail about
when and roughly where the rip currents are most likely to be forming
(e.g. east facing beaches) and how long the conditions are likely to
continue. The statement is issued using the Coastal Hazard Message.
Severe Thunderstorm Watch:
A watch issued when conditions become favorable for
severe thunderstorms to develop and headlined in the Coastal Waters
Forecast, the Great Lakes Open Lakes Forecast, and the Nearshore Marine
Forecast. Reference NWSI 10-512 for severe thunderstorm watch criteria.
Special Marine Warning (SMW):
A warning product issued for potentially hazardous
weather conditions usually of short duration (up to 2 hours) producing
sustained marine thunderstorm winds or associated gusts of 34 knots or
greater; and/or hail 3/4 inch or more in diameter; and/or waterspouts
affecting areas included in a Coastal Waters Forecast, a Nearshore
Marine Forecast, or an Great Lakes Open Lakes Forecast that is not
adequately covered by existing marine warnings. Also used for short
duration mesoscale events such as a strong cold front, gravity wave,
squall line, etc., lasting less than 2 hours and producing winds or
gusts of 34 knots or greater.
Storm Watch: A
watch for an increased risk of a storm force wind event for sustained
surface winds, or frequent gusts, of 48 knots (55 mph) to 63 knots (73
mph), but its occurrence, location, and/or timing is still uncertain.
Tornado Watch:
A watch issued when conditions become favorable for tornadoes to develop
and headlined in the Coastal Waters Forecast, the Great Lakes Open Lakes
Forecast, and the Nearshore Marine Forecast . Reference NWSI 10-512 for
tornado watch criteria.
Tropical Storm Watch:
An announcement that tropical storm conditions (sustained
winds of 39 to 73 mph) are possible within the specified coastal area
within 48 hours.
Definitions from the
National
Weather Service
