Alerta de Condição Whiteout
A warning indicating that visual navigation is severely hindered due to uniformly diffuse light caused by snow, ice, or fog, often resulting in total loss of horizon distinction.
View termCategories
Meteorology
Browse Meteorology terms for maritime professionals.
Languages
Alerta de Crista de Pressão
A notice regarding the formation or presence of elevated ice ridges on sea ice, which may pose navigational hazards to vessels in polar waters.
View termAlerta de Derrame de Óleo
Immediate notification that mineral oil is observed on sea surface requiring containment and reporting under MARPOL 73/78.
View termAlerta de Frente Ocluído
Notification that a mature occluded front will pass the vessel’s vicinity, often associated with variable winds and squally showers.
View termAlerta de Onda de Frio
An official warning issued to inform mariners of an expected period of unusually low temperatures, which may affect vessel systems and crew safety.
View termAlerta de Tempestade Tropical
An official advisory issued to warn vessels that a tropical storm may affect the area within 48 hours. Mariners should closely monitor forecasts and prepare for possible severe weather.
View termAlerta Linha de Rajada
Notification that organised line of squalls with gusts ≥ 34 kn is approaching, often ahead of cold front.
View termAproximação de Frente Fria
A message or forecast that a cold front is moving into the operational area, often accompanied by abrupt wind shift, falling temperatures, and changing sea state.
View termAproximação de Frente Quente
Indication that a warm air mass front is advancing toward the vessel’s area, typically bringing steady rain and veering winds.
View termAtualização de Corrente de Maré
New information on rate and set of tidal current issued by VTS or hydrographic authority for local area.
View termAviso de Acumulação de Gelo
Notice that superstructure icing rate exceeds 2 cm h⁻¹ due to freezing precipitation or spray, requiring anti-icing measures.
View termAviso de Altura de Onda
A warning issued to vessels regarding anticipated significant wave heights exceeding safe operating limits.
View termAviso de Atividade de Relâmpagos
Alert issued when frequent cloud-to-ground or cloud-to-cloud lightning poses immediate risk to deck personnel and sensitive equipment.
View termAviso de Chuva Congelante
GMDSS forecast message indicating super-cooled rain likely to freeze on contact, causing rapid ice accretion on decks and rigging.
View termAviso de Chuva Forte
GMDSS meteorological message signalling precipitation rate ≥ 50 mm in 6 h, causing reduced visibility and risk of runoff.
View termAviso de Chuva Torrencial
An official advisory issued to warn of intense and prolonged rainfall that may severely reduce visibility and increase risk of flooding and navigation hazards.
View termAviso de Ciclone
Official alert issued when a tropical cyclone with gale-force winds is expected to affect a maritime area within 24 hours.
View termAviso de Corrente Costeira
Official notice to mariners about significant changes, hazards, or anomalies in coastal water currents affecting safe navigation.
View termAviso de Corrente de Superfície
Official MSI or VHF message advising mariners that abnormally strong or variable surface currents exist in a defined area and may affect safe navigation.
View termAviso de Formação de Névoa
An official advisory indicating that atmospheric conditions are favorable for mist development, which may lower visibility and affect navigation safety.
View termAviso de Furacão
A formal announcement by maritime or meteorological authorities indicating that hurricane conditions, including very high winds and heavy seas, are expected in the area.
View termAviso de Gelo Fragmentado
Message issued by ice services or VTS indicating dangerous concentrations of brash ice likely to impede manoeuvring or clog sea intakes.
View termAviso de Growler Ice
Alert indicating presence of small, dense glacial ice blocks (growlers) scarcely visible above water, posing collision risk.
View termAviso de Mancha de Névoa
Notice to mariners of localised fog banks that may suddenly reduce visibility and require speed reduction or additional lookout.
View termAviso de Maré de Tempestade
An official alert issued to vessels regarding an abnormally high rise of sea level due to meteorological effects, especially during storms.
View termAviso de Neve Intensa
Forecast advising imminent heavy snowfall reducing visibility below 0.5 nm and affecting mooring or channel transit.
View termAviso de Nevoeiro Denso
Warning issued when visibility expected below one-half nautical mile due to thick fog, requiring sound signals and speed reduction.
View termAviso de Nevoeiro Marítimo
Notice that horizontal visibility at sea will fall below one kilometre due to advection or radiation fog.
View termAviso de Névoa Congelante
An advisory issued to warn vessels of freezing fog conditions, which may cause ice accumulation on decks, equipment, and navigation structures.
View termAviso de Passagem de Frente
A formal advisory issued by maritime authorities warning vessels of an approaching frontal system likely to bring sudden changes in wind, temperature, and visibility conditions.
View termAviso de Ressaca de Tempestade
Warning that abnormal sea-level rise due to cyclonic surge is expected in coastal area, requiring preventive mooring and evacuation measures.
View termAviso de Spray Congelante
GMDSS meteorological warning that sea spray will freeze on exposed surfaces causing topside icing hazards.
View termAviso de Tempestade
A formal notification from maritime or meteorological authorities indicating strong winds, heavy seas, and potentially hazardous conditions are expected in the designated area.
View termAviso de Tufão
Highest-level tropical-cyclone warning issued by JMA or PAGASA for winds ≥64 kt, heavy seas and extreme storm surge threatening coastal and open-sea areas.
View termAviso de Vendaval
A warning issued to mariners when sustained winds of Beaufort Force 8 or higher (34–40 knots) are expected or occurring in the area.
View termAviso de Visibilidade Reduzida
A formal alert issued to vessels when fog, mist, precipitation, or other factors are expected to lower visibility below safe navigation thresholds.
View termBoletim de Risco de Tromba d’Água
An official maritime bulletin advising of the risk of waterspout formation in a specific sea area, requiring heightened lookout and precautionary measures.
View termBoletim de Tempestade Severa
Official GMDSS warning message indicating winds ≥ Beaufort 10, heavy seas and reduced visibility within forecast area.
View termBoletim Meteorológico GMDSS
Scheduled meteorological broadcast issued via NAVTEX, HF, MF or satellite under the Global Maritime Distress and Safety System.
View termCarta de Pressão à Superfície
Synoptic weather map depicting isobars and pressure systems at mean sea level, used for routeing decisions.
View termConcentração de Gelo Marinho
A measure (usually in tenths) of the area of a sea region covered by ice, provided in ice bulletins to support safe navigation and routing.
View termConteúdo de Calor do Oceano
Measure of thermal energy stored in the upper ocean layers, used to assess cyclone potential and climate trends.
View termCrista de Alta Pressão
An elongated area of high atmospheric pressure, typically associated with calm weather and stable sea conditions.
View termExercício de Controle de Poluição
Planned harbour drill simulating oil-spill response, including boom deployment, skimmer operation and multi-agency communications testing.
View termExpansão de Gelo Fixo
Rapid seaward growth of shore-fast ice, restricting manoeuvring space and increasing risk of besetment for vessels.
View termInspeção de Antiincrustação
Port state or class survey checking hull coating compliance with IMO AFS Convention and assessing biological growth.
View termInventário de Gases de Efeito Estufa
Comprehensive report of CO₂, CH₄ and N₂O emissions from vessel operations for regulatory compliance and environmental management.
View termNotificação de Impacto Ambiental
Formal notification detailing projected ecological effects of vessel operations or construction works, issued for regulatory approval.
View termObservação de Onda de Calor
Pre-warning by meteorological authority that sustained high air temperatures are likely within 48 h, possibly affecting crew endurance, vessel machinery and cargo.
View termObservação Meteorológica do Navio
Recorded meteorological observations from ships, submitted to authorities or meteorological agencies for forecasting and safety.
View termPedido de Previsão Metarea
Vessel’s formal demand via GMDSS for the latest meteorological forecast for a specific NAVAREA/METAREA region.
View termPerspectiva de Trovoadas
Prognostic bulletin giving probability, timing and movement of convective cells within shipping area.
View termPlano de Gerenciamento de Bioincrustação
A documented system required by IMO for vessels to manage and minimize the accumulation of aquatic organisms on hulls and submerged structures.
View termPrevisão da Maré de Enchente
Forecast information regarding the timing and height of the next incoming (flood) tide, crucial for safe navigation and berthing operations.
View termPrevisão de Deriva de Gelo
Forecast of movement and speed of pack or floe ice issued by ice service for route planning.
View termPrevisão de Deriva de Iceberg
A prediction of the future movement and position of icebergs in a given maritime area, based on meteorological and oceanographic data, issued to assist in safe navigation.
View termPrevisão de Vazante
Tabulated forecast time and rate of falling tide current used for harbour passage planning.
View termProcedimento de Abatimento de Ruído
Harbour authority directive requiring vessels to minimise machinery and whistle noise, especially at night, to protect nearby communities and sensitive wildlife.
View termProcedimento de Controle VOC
Shipboard plan to minimise Volatile Organic Compound emissions during loading, voyage and discharge of crude oil cargoes per IMO Resolution 1088(28).
View termRecebimento de Carta Radiofax
Confirmation that a complete facsimile weather chart has been successfully received via HF radio and is ready for navigation use.
View termRegistro de Descarga de Lixo
A mandatory logbook entry or record made by the ship to document every instance of garbage discharge or disposal at sea or at port, as required by MARPOL regulations.
View termRelatório de Borda de Gelo
Update giving the geographic position of the ice edge separating open water from pack ice, critical for polar routing.
View termRelatório de Código Sinóptico
A standardized numerical weather message (per WMO/IMO) reporting synoptic-scale observations, transmitted by ships for meteorological analysis and forecasting.
View termRelatório de Dados Oceanográficos
A formal report or transmission containing oceanographic data such as temperature, salinity, current, and sea state, as collected by shipboard sensors or via official request.
View termRelatório de Direção da Ondulação
Statement giving the dominant direction, height and period of the prevailing ocean swell for route planning and seakeeping.
View termRelatório de Direção do Vento
An official meteorological report or observation stating the current direction from which the wind is blowing, vital for navigation and maneuvering.
View termRelatório de Lixo Marinho
A report made to authorities or VTS regarding observed floating or drifting marine debris that may pose a hazard to navigation.
View termRelatório de Observação de Névoa
A message reporting reduced visibility due to haze, specifying affected areas and visibility range, commonly issued for safety in coastal and open sea zones.
View termRelatório de Pedaço de Gelo
An official communication or broadcast of the sighting and position of medium-sized floating ice fragments (bergy bits), especially in northern sea routes.
View termRelatório de Pressão Barométrica
Regularly transmitted statement of current atmospheric pressure and trend for meteorological data exchange and storm tracking.
View termRelatório de Tendência Barométrica
Synoptic code group summarising rate and character of atmospheric pressure change during past three hours, broadcast in SHIP and METAR messages.
View termRelatório do Estado do Mar
Periodic description of significant wave height, period and swell state transmitted for routing and safety assessments.
View termSinal de Vendaval Severo
An official maritime signal indicating imminent or present severe gale conditions (Beaufort Force 9–10) requiring vessels to secure for heavy weather.
View termTemperatura da Superfície do Mar
Measured or satellite-derived temperature of ocean top centimetre, critical for routing, icing and cyclogenesis forecasts.
View termTroca de Água de Lastro
Operation of replacing loaded ballast with mid-ocean water at prescribed distance from land to prevent bio-invasion, logged under IMO BWM Convention.
View termVento de Força Furacão
Wind of Beaufort scale 12 (≥ 64 kn) producing phenomenal seas; reported in Metarea bulletins as force 12.
View termÁrea de Baixa Pressão
A meteorological region where atmospheric pressure is lower than surrounding areas, often associated with unsettled weather, strong winds, and possible cyclonic activity affecting maritime operations.
View termÁrea de Controle de Emissões
Designated sea region where MARPOL Annex VI limits on SOx, NOx and PM apply; requires low-sulphur fuel or equivalent abatement.
View termÍndice de Eficiência Energética
Calculated parameter (EEXI/EEOI) expressing CO₂ emitted per transport work, mandatory under IMO MARPOL Annex VI.
View term