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Weather Flags

Last modified: 2010-07-10 by phil nelson
Keywords: weather flags |
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Overview

The WMO (World Meteorological Organization) shows a number of flags an pennants in Annex II. National Systems of Visual Storm Warning Signals (Day Signals).

Chapter 8, part of Vol. D `Information for Shipping', one of WMO's operational documents. The introduction to this Chapter states:

As stipulated in the International Convention for the Safety of Life at Sea (…), Countries concerned should display at coastal points appropriate visual storm warning signals when applicable.

WMO Technical Regulations specifies that any Member establishing a new visual storm warning signal system should adopt the international system.

This part contains information on the systems of visual storm warning systems adopted by the various maritime countries. Where no such signals are used, a statement to this effect is given.

Annex I shows the International System of Visual Storm Warning Signals: black flags describing wind force (bottom of page) which may be however of another colour, if suitable.

There is also a breakdown of signals by country.

This very interesting table mentions countries with or without (official) warning system.

To give a few examples: Egypt uses two yellow crossed anchors on a white field (50a) meaning "Too much sea, pilot can not go out". (51a) being a blue flag pierced yellow is a signal "indicating the locality of storms" in Thailand ("South China Sea bordered by southern Viet Nam coast", etc.). Tunisia does not use signals whereas Sri Lanka uses a single one, but it is not a flag.
Jan Mertens, 27 October 2007


[Editorial Note: The images on this page are shown at a standard height. Some may be viewed in the FOTW standard size by clicking on the image. Items listed as "contributed by" may be smaller than FOTW standard size]


Angola

Angola uses the international system.
Jan Mertens, 1 November 2007


Anguilla

Anguilla uses a partial use of the well-known US signal set.

images by António Martins-Tuválkin, 15 August 1999
56a (red pennant): "Winds 28-33 kt."

[information flag]

 
40a (red pierced black): "Winds 34-63 kt."

[gale warning flag]

 
41a (double set of red pierced black): "Winds above 63 kt."

[gale warning flag]

[gale warning flag]

Jan Mertens, 23 March 2008


Antigua and Barbuda

Antigua and Barbuda use signals 40a and 41a which are red pierced black and red pierced black (double), respectively.

Signal 40a
[gale warning flag] image by António Martins-Tuválkin

40a is defined as "Tropical disturbance reported; likely to affect the island"

Signal 41a

[gale warning flag]

[gale warning flag]

image by António Martins-Tuválkin

whereas 41a means Hurricane warning. Danger expected.
Jan Mertens, 1 November 2007


Argentina

Argentina does not use such signals although the introduction of the international system is planned.
Jan Mertens, 1 November 2007


Australia

Australia does not have a national system, however "the control of the various major shipping ports in Australia is vested in various State and Local Authorities, some of whom exhibit local signals".
Jan Mertens, 1 November 2007


Azores

Portugal

The Azores use signal uses a black double cone.
Jan Mertens, 1 November 2007


Bangladesh

Bangladesh uses an elaborate warning system, however there is not a single flag among these signals.
Jan Mertens, 2 November 2007


Barbados

According to the WMO, Barbados uses signals 45a and 41a:

45a, a green flag, is defined as "The island is out of danger. The green flag of the day signal has a white diagonal stripe" which really means that the 45a picture does not apply to Barbados, as it is incomplete.

Signal 41a

[gale warning flag]

[gale warning flag]

image by António Martins-Tuválkin

41a is the well-known set of two black flags pierced red, meaning "Hurricane conditions are expected within 24 hours."
Jan Mertens, 3 November 2007


Belize

Belize uses following flags:

Tropical Depression/Storm

Belize tropical depression/storm image by António Martins-Tuválkin, 9 August 2007

43a (plain red):

(i) "A tropical depression moves into or develops anywhere in the quadrant south of 211°N latitude and west of 80°W longitude, OR

(ii) A tropical storm or hurricane moves into or develops anywhere in the quadrant south of 21°N latitude and between longitudes 80°W and 83°W".

Storm has passed

Belize storm has passed image by António Martins-Tuválkin, 9 August 2007

45a (green): "The tropical depression, tropical storm or hurricane has passed or not longer poses a threat to Belize and coastal waters."

Tropical Storm Warnings

hurricane warning

hurricane warning

image by António Martins-Tuválkin, 9 August 2007

41a (double set of red pierced black): "A tropical storm or hurricane moves into or develops anywhere in the quadrant south of 20° N latitude and west of 85°W longitude."

tropical storm/hurricane image by António Martins-Tuválkin, 9 August 2007

40a (red pierced black): "A tropical [storm] or hurricane moves into or develops anywhere in the quadrant south of 20°N latitude and between longitudes 83°W and 85°W."

However the above needs to be qualified: Specifically the black rectangle is replaced by a black dot.
Jan Mertens, 4 November 2007


Brazil

Brazil uses the international system.
Jan Mertens, 4 November 2007


Cambodia

Cambodia does not use weather signals.
Jan Mertens, 4 November 2007


Cameroon

Cameroon uses the international system.
Jan Mertens, 4 November 2007


Cayman Islands

The Cayman Islands uses a series of signal flags – pennants, to be exact – related to, but different from, hurricane warning flags. See the Caymen Islands preparedness page.

The captions eventually lead small images of the pennants. There are four of them

storm alert
Tropical Storm Alert flag: a red pennant

all clear
Tropical Storm All Clear flag: a green pennant

tropical storm warning
Tropical Storm Warning flag: two red pennants with black triangle pointing outwards.

tropical storm watch
Tropical Storm Watch flag: red pennant with black triangle pointing outwards.

P. 36 of the hurricane plan (PDF) states that in case of an alert, “The Commissioner of Police will arrange to have one red flag hoisted at the designated buildings”.

P. 37 states that in the case of a watch, “one red flag with black centre [is] to be hoisted at each designated building”. P. 39 mentions the warning sign, “two red flags with black centres” whereas the all clear sign “one green flag” is mentioned on p. 40.
Jan Mertens, 13 January 2008


Chile

Chile uses a separate system (only the flags will be mentioned).

Variable Weather

variable weather image contributed by Jan Mertens, 5 November 2007

48a (blue pennant with small white dot enclosed by black circle): “Variable [weather]”.

Loading/Unloading of Cargo suspended

variable weather image contributed by Jan Mertens, 5 November 2007

47a (red, rectangular, with yellow cross throughout): “The traffic, loading and unloading of cargo are totally suspended; lighters and tugs should make fast.” Attached as < cl_vsws47a.gif> .

Small craft traffic suspended

variable weather image contributed by Jan Mertens, 5 November 2007

46a (blue, rectangular, with white saltire): “The traffic of small craft is suspended in the bay on account of bad weather.”

There is a note (a) saying that “these signals correspond to the current synoptic chart”, a further note (b) is not flag related.
Jan Mertens, 5 November 2007


Costa Rica

According to the WMO: "At present there is no national or international system of visual storm warning signal in general use in Costa Rica."
Jan Mertens, 5 November 2007


Côte d’Ivoire

Côte d'Ivoire uses the international system.
Jan Mertens, 5 November 2007


Djibouti

Djibouti uses the international system.
Jan Mertens, 5 November 2007


Egypt

Egypt uses an elaborate warning system: comprising only one flag:

Egyptian weather flag image by Eugene Ipavec, 8 November 2007

50a (white, two yellow anchors, crossed, the stocks turned towards the hoist): “Too much sea, pilot can not go out”. Attached as < eg_vsws50a.gif> .
Jan Mertens, 7 November 2007


Fiji

Fiji uses one signal, which is a flag:

Fiji weather flag image by Eugene Ipavec, 21 December 2007

35a: yellow pennant meaning “Storm/hurricane alert. A tropical cyclone of storm or hurricane intensity exists and may affect the locality within 24 or 36 hours.”
Jan Mertens, 8 November 2007


France

France uses the international system.
Jan Mertens, 8 November 2007


French Polynesia

French Polynesia uses the international system.
Jan Mertens, 8 November 2007


Gabon

Gabon uses the international system.
Jan Mertens, 8 November 2007


Gambia

Gambia uses the international system.
Jan Mertens, 8 November 2007


Ghana

Ghana uses a single signal, which is not a flag. Jan Mertens, 8 November 2007


Gibraltar

Gibraltar uses a few signals none of which is a flag. Jan Mertens, 8 November 2007


Grenada

Grenada uses a signal flag set closely resembling US use:

Winds: above 63 knots

hurricane warning

hurricane warning

image by António Martins-Tuválkin

41a (double set of red pierced black): "Winds above 63 kt".

Winds: 34-63 knots

hurricane warning image by António Martins-Tuválkin

40a (red pierced black): "Winds 34-63 kt".

Winds: 28-33 knots

[information flag] image by António Martins-Tuválkin

56a (red pennant): "Winds 28-33 kt"
Jan Mertens, 9 November 2007


India

India uses an elaborate signalling system, but no flag(s).
Jan Mertens, 16 November 2007


Israel

Israel uses a few signals, but there is no flag among them.
Jan Mertens, 16 November 2007


Italy

Italy uses a few signals, but there is no flag among them.
Jan Mertens, 16 November 2007


Korea (Republic of Korea) [South Korea]

South Korea does not use visual warning signals at present. Instead, radio is used.
Jan Mertens, 23 March 2008


Madagascar

Madagascar uses the international system.
Jan Mertens, 10 February 2008


Malaysia

Malaysia uses "For national coastal waters, visual strong wind and rough sea warnings at Kuala Trengganu and Tumpat. Notice board display of information on strong wind and rough sea at Mersing and various fisheries departments in Pahang."

It is not said how these visual warnings look like.
Jan Mertens, 10 February 2008


Malta

Malta uses a number of signals but there is no flag among them.
Jan Mertens, 24 February 2008


Mozambique

Mozambique adheres to the international system – 6a is a single black rectangular flag, 7a two black rectangular flags above each other.
Jan Mertens, 2 March 2008


Mauritania

Mauritania uses the international system.
Jan Mertens, 24 February 2008


Myanmar

Myanmar uses an extensive number of signals but there is no flag among them. Jan Mertens, 9 March 2008


Netherlands

The Netherlands follow the international specification. Also: "Night signals are displayed at Flushing, Hook of Holland, IJmuiden, Den Helder and Terschelling. Day signals are not displayed."
Jan Mertens, 9 March 2008


Netherlands Antilles

The Netherlands Antilles use the well-known US signal set but with local differences.

Curaçao, Aruba, and Bonaire

40a (red pierced black): "Gale warning: winds 39 miles an hour (34 kt) and upwards.

[gale warning flag]
image by António Martins-Tuválkin,
15 August 1999


St. Maarten, Saba, and St. Eustatius

images by António Martins-Tuválkin, 15 August 1999
56a. Small craft warning: winds and seas or sea conditions are only dangerous to small craft operations. Winds range up to 38 miles an hour (33 kt)

[information flag]

 
39a. Gale warning: winds within the range 39-54 miles an hour (34-47 kt).

[information flag]

[information flag]

 
40a. Whole gale warning: winds within the range 55 to 73 miles an hour (48 to 63 kt)

[gale warning flag]

 
41a. Hurricane warning: winds 74 miles an hour (64 kt) and upwards.

[gale warning flag]

[gale warning flag]

Jan Mertens, 16 March 2008


Nigeria

Nigeria adheres to the international system.
Jan Mertens, 9 March 2008


Norway

Norway uses a number of signals but there is no flag among them.
Jan Mertens, 9 March 2008


Portugal

Portugal uses an extensive number of signals among which there are two flags (of the international system):

7a (set of two black flags, one above the other): "Wind expected to back (counter-clockwise change in direction).

6a (black flag): "Wind expected to veer (clockwise change in direction).
Jan Mertens, 16 March 2008


Pakistan

Pakistan uses an extensive number of signals but there is no flag among them.
Jan Mertens, 9 March 2008


Philippines

The Philippines uses the international system.
Jan Mertens, 9 March 2008


Saint Kitts and Nevis

St Kitts and Nevis use a subset of the US signals.

images by António Martins-Tuválkin, 15 August 1999
56a (red pennant): "Winds 28-33 kt."

[information flag]

 
40a (red pierced black): "Winds 34-63 kt."

[gale warning flag]

 
41a (double set of red pierced black): "Winds above 63 kt."

[gale warning flag]

[gale warning flag]

Jan Mertens, 23 March 2008


Samoa

Samoa uses one signal which is a flag

storm warnign flag image by Eugene Ipavec, 21 December 2007

35a: yellow pennant meaning “Storm/hurricane alert. A tropical cyclone of storm or hurricane intensity exists and may affect the locality within 24 or 36 hours.
Jan Mertens, 30 March 2008


United States

Information Signals

U.S. Weather Service flags
(general)

images by Phil Nelson and António Martins-Tuválkin (information flag)
[click on flag for larger image]

Fair Weather

[fair weather flag]

Rain or Snow

[rain or snow flag]

Information

[information flag]

Local Rain or Snow

[local rain or snow flag]

Cold Wave

[cold wave flag]

Temperature Change

[temperature change flag]

There is an interesting set of signal flags that are (were) used as weather signals by the US Department of Agriculture. Perhaps these went out of use with the widespread use of radio in the early years of this century (or maybe they are still used?  This is what "The World Almanac" (1893) had to say (my comments in square brackets):

"The weather bureau furnishes, when practicable, for the benefit of the general public and those interests dependent to a greater or less extent upon weather conditions, the 'forecasts' which are prepared at that office daily at 10am and 10pm, for the following day. These weather forecasts are telegraphed to observers at stations of the weather bureau, railway officials, and many others, and are so worded as to be readily communicated to the public by means of flags or steam whistles. The flags adopted for this purpose are five in number, and of the form and dimensions indicated below:

1. White flag, six feet square [1800mm], indicates clear or fair weather.

2. Blue flag, six feet square, indicates rain or snow.

3. White and blue flag (parallel bars of white and blue)*, six feet square, indicates that local rains or showers will occur, and that the rainfall will not be general
*an accompanying picture indicates a horizontal bicolour, white over blue

4. Black triangular flag four feet at the base [presumably hoist; 1200mm] and six feet in length, always refers to temperature.

When placed above [previously mentioned flags] number 1, 2, or 3 it indicates warmer weather; when placed below numbers 1, 2, or 3 it indicates colder weather; when not displayed, the indications are that the temperature will remain stationary, or that the change in temperature will not vary more than four degrees [Fahrenheit] from the temperature of the same hour of the previous day from March to October inclusive, and not more than six degrees for the remaining months of the year.

Temperature Change Signals
images by Phil Nelson
[click on flag for larger image]
  Fair Weather Rain/Snow Local Rain/Snow
No major change
from previous day

[fair weather flag]

[rain or snow flag]

[local rain or snow flag]

Rising Temperature

[temperature change flag]

[fair weather flag]

[temperature change flag]

[rain or snow flag]

[temperature change flag]

[local rain or snow flag]

Falling Temperature

[fair weather flag]

[temperature change flag]

[rain or snow flag]

[temperature change flag]

[local rain or snow flag]

[temperature change flag]

 

5. White flag, six feet square, with black square in centre [picture suggests two feet/600mm square], indicates the approach of a sudden and decided fall in temperature. This flag is not to be displayed unless it is expected that the temperature will fall to forty-two degrees or lower, and is usually ordered at least twenty-four hours in advance of the cold wave. When number five is displayed, number four is omitted, but it may be displayed above either flag 1 or 2. Cold Front Signals
[click on flag for larger image]
Cold Front
Precipitation
Cold Front
Fair Weather

[cold wave flag]

[rain or snow flag]

[cold wave flag]

[fair weather flag]

 

A special Storm flag, red with black square in the centre, is prescribed for use in North and South Dakota, Minnesota (except at lake stations), Iowa, Nebraska, and Wyoming, to indicate high winds, accompanied by snow, with temperature below freezing.

When displayed on poles, the signals should be arranged to read downward; when displayed from horizontal supports, a small streamer [colour unspecified] should be attached to indicate the point from which the signals are to be read."
James Dignan, 06 December 1997


Wind Direction Signals

U.S. Weather Service flags
(wind direction signals)

images by António Martins-Tuválkin, 15 August 1999, 9 November 2006
[click on flag for larger image]
Northwest winds

[information flag]

[gale warning flag]

 
Northeast winds

[information flag]

[gale warning flag]

 
Southwest winds

[gale warning flag]

[information flag]

 
Southwest winds

[gale warning flag]

[information flag]

These flags are depicted in "Signal flags used at Weather Bureau Display Stations" In: The Aims and Methods of Meteorological Work by Cleveland Abbe. In: Maryland Weather Service, Johns Hopkins Press, Baltimore, 1899. Vol I. Page 296.

Red pennant above square red flag pierced black: captioned "N.E. WINDS".

Square red flag pierced black above red pennant: captioned "S.E. WINDS".

White pennant above square red flag pierced black: captioned "N.W. WINDS".

Square red flag pierced black above white pennant: captioned "S.W. WINDS".

WIND SIGNAL. Pennants with the Storm Signal indicate the direction of the wind; red, easterly. from northeast to south; white, westerly, from southwest to north. The Pennant above the flag indicates that the wind is expected to blow from the northerly quadrants; below, from the southerly quadrants.

Jan Mertens, 7 November 2005


Coastal Storm Signals

U.S. Weather Service flags
(coastal storm signals)

images by António Martins-Tuválkin, 15 August 1999
[click on flag for larger image]
Small Craft Warning

[information flag]

 
Gale Warning

[information flag]

[information flag]

 
Storm/Full Gale Warning

[gale warning flag]

 
Hurricane Warning

[gale warning flag]

[gale warning flag]

From navytimes.com:

Coasties revive foul-weather warning flags
By Patricia Kime - Staff writer
Posted : Wednesday May 30, 2007 18:19:14 EDT

Double red-and-black storm-warning flags once heralded an impending hurricane, urging mariners to take cover and seaside residents to flee.

The flags disappeared from common use in 1989, when the National Weather Service discontinued the program.

This summer, the Coast Guard officially is bringing them back.

Starting June 1, select Coast Guard stations will hoist storm flags in foul weather: red triangle for small craft warning; double red triangle for gale warning; single red-and-black square for storm warning; and the feared double flags for hurricane warning.

“[This is] a Coast Guard initiative to reinforce the Coast Guard’s role as lifesavers, reaffirm to local communities the Coast Guard’s role as experts concerning local boating matters and visually communicate ... the lesson of Hurricane Katrina to take personal responsibility for individual safety,” said Rear Adm. David Pekoske in an announcement May 30.

Some marinas and stations voluntarily have carried on the tradition of hoisting such flags, but participation was spotty.

The Coast Guard hopes that residents in storm-prone areas will see the flags and listen to National Oceanographic and Atmospherics Administration radio broadcasts for further details, officials say.

According to NOAA, more than half the country’s population lives along the coasts. In 2003, roughly 153 million people lived in 673 coastal counties.

David C. Fowler, 31 May 2007

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