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Visual Storm Warning Signals (Thailand)

Last modified: 2023-06-03 by zachary harden
Keywords: thailand | weather flags | visual storm warning signal |
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Introduction

According to this WMO page (PDF, link not working), Thailand uses two flags we know from the well-known US signal set (also PDF, also not working), plus a number of others which are specific. Basically there are two groups of signals, one set “indicating the locality of storms”, the other “intensity of storms” (correcting an obvious illogicality in the text). Both may be hoisted together however, while a special case is the signal for normal weather conditions.

Jan Mertens, 13 Apr 2008

Locality Flags

 [Area 1 Signal (Thailand)] 7:10
image by Eugene Ipavec, 19 Apr 2008

37a (yellow flag) concerns “Area 1: Gulf of Thailand east coast to Lat. 5°N and Long. 105°E”.

[Area 2 Signal (Thailand)] 7:10
image by Eugene Ipavec, 19 Apr 2008

38a (blue flag) concerns “Area 2: Gulf of Thailand west coast to Lat. 5°N”.

[Area 3 Signal (Thailand)] 7:10
image by Eugene Ipavec, 19 Apr 2008

43a (red flag) concerns “Area 3: Andaman Sea bounded by west coast of southern Myanmar, west coast of southern Thailand. Long. 97°E, Lat. 5°N and Lat. 14°N”.

[Area 4 Signal (Thailand)] 7:10
image by Eugene Ipavec, 19 Apr 2008

51a (blue flag pierced yellow) concerns “Area 4: South China Sea bounded by southern Viet Nam coast, Lat. 12°N, Lat. 5°N, Long. 105°E and Long. 112°E”.

Intensity Pennants

 [64 kt+ Typhoon Signal (Thailand)] 4:5
image by Eugene Ipavec, 19 Apr 2008

56a (red pennant): “Typhoon or cyclone or storm with wind speeds near center 64 kt and upwards”.

[34-63 kt Typhoon Signal (Thailand)] 4:5
image by Eugene Ipavec, 19 Apr 2008

36a (blue pennant): “Tropical storm or storm with wind speeds near center from 34 kt and over but not exceeding 63 kt”.

[>33 kt Typhoon Signal (Thailand)] 4:5
image by Eugene Ipavec, 19 Apr 2008

35a (yellow pennant): “Tropical depression or storm with wind speeds near center not exceeding 33 kt”.

There are two notes:

  • Note 1 specifies that “Signals indicating the occurrence of storms in the Gulf of Thailand and adjacent seas [are] to be displayed at: Port Area (Bangkok); and Bangkok Harbour Limit I (Pong Pachjamit Port, Pagklongsarn, Dhonburi).
  • Note 2 specifies that “Signals indicating the intensity and locality of storms will be hoisted on the same yard-arm with the pennant indicating the intensity and the flag indicating the locality of the storm. The flag is always hoisted below the pennant.”
[Normal Weather Conditions Signal (Thailand)] 4:5
image by Eugene Ipavec, 19 Apr 2008

Finally, “at normal weather conditions (no tropical depression of storm or typhoon) the white pennant with red circle (52a) will be displayed at the upper yard-arm at Bangkok Harbour Limit I (Pong Pachjamit Port, Pagklongsarn, Dhonburi)”.

Jan Mertens, 13 Apr 2008