Weather Flags (U.S.)

Last modified: 2016-03-05 by rick wyatt
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• United States
• Information Signals
• Wind Direction Signals
• Coastal Storm Signals
• Hydrographic and Beach Markings

See also:

• Older weather signal flags
• Storm signal flags
• Weather Flags
• FOTW Vexillological reference
• United States of America

United States

Information Signals

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.

 

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

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, 6 December 1997

Wind Direction Signals

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.

Coastal Storm Signals

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