SYNOP

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SYNOP (stem of "synchronous" and "optical") is an acronym for synoptic observation , ie a weather report.

Weather observations are coded worldwide according to a special number key. The SYNOP code has fixed components and is always structured in the same form in order to make the observation comprehensible for others. The code has been defined by the World Meteorological Organization (FM-12 for fixed radio stations, FM-13 for marine radio stations ).

SYNOP code

IIiii iihVV Nddff 00fff 1sTTT 2sTTT 3PPPP 4PPPP 5appp 6RRRt 7wwWW 8NCCC 9GGgg

Each SYNOP code consists of a five-digit series of numbers. The weather observations are coded and entered one after the other. Each row contains a measured value, with the exception of the first, which is used to identify the reporting (manned or automatic) weather station or a weather ship . The first number of each series of numbers (with the exception of the station reporting group and the cloud / wind group Nddff) provides information about the type of measured value reported.

Example:

10637 41570 53035 10054 21011 40158 52021 60062 72186 82842 91150


Explanation of the groups of five:


IIIiii (example: 10637)

  • II = block number (code number of the country or, in the case of large states, a part of the country)
    • 10 = Germany
  • iii = station code
    • 637 = Frankfurt / Main - Airport


iihVV (example: 41570)

  • i = indicator for reporting the amount of precipitation
    • 4 = Notification of precipitation on the date not planned
  • i = indicator for the type of station (manned or automatic and for reporting the current weather situation)
    • 1 = Station manned, reportable weather phenomena under number 7 are available
  • h = cloud base of the deepest clouds
    • 5 = Between 600 m and 999 m above the station
  • VV = horizontal visibility
    • 70 = 20 kilometers (km)


Nddff (example: 53035)

  • N = total sky coverage in eighths (visible sky area)
    • 5 = 5 eighths (5/8)
  • dd = wind direction in tens of degrees (direction from which the wind is coming)
    • 30 = 300 degrees (from west northwest)
  • ff = wind speed in knots. (If a 99 is coded, the wind speed is 99 knots or more. The exact value is then in the following group.)
    • 35 = 35 knots (approx. 63 km / h = stormy wind)


00fff (not reported in the example)

  • 00 = identifier for specifying wind speeds of 99 knots or more. (If the wind speed is lower, this group does not apply.)
  • fff = wind speed in knots.


1sTTT (example: 10054)

  • 1 = Identifier for the air temperature 2 m above ground
  • s = sign of the temperature (0 = positive / 1 = negative)
  • TTT = air temperature in tenths of a degree Celsius 2 m above ground
    • 054 = 5.4 ° C, since s = 0 so +5.4 ° C.


2sTTT (example: 21011)

  • 2 = Identifier for the dew point temperature 2 m above ground
  • s = sign of the dew point temperature (0 = positive / 1 = negative)
  • TTT = dew point temperature in tenths of a degree Celsius 2 m above ground
    • 011 = 1.1 ° C, since s = 1, i.e. −1.1 ° C


3PPPP (not reported in the example)

  • 3 = ID for the air pressure group , air pressure measured at barometer height
  • PPPP = ward air pressure in tenths of a hectopascal, omitting the thousands figure


4PPPP (example: 40158)

  • 4 = ID for the air pressure group
  • PPPP = station air pressure reduced to sea level in tenths of a hectopascal, omitting the thousands figure
    • 0158 = 1015.8 hectopascal (hPa)


5appp (example: 52021)

  • 5 = ID of the air pressure tendency group
  • a = type of air pressure change during the last 3 hours
    • 2 = steadily increasing; higher than 3 hours ago
  • ppp = amount of 3-hour barometric pressure changes in tenths of a hectopascal
    • 021 = 2.1 hPa (hectopascal)


6RRRt (example: 60062)

  • 6 = identifier of the precipitation group (not applicable if no precipitation has fallen)
  • RRR = amount of precipitation in whole mm (exception: 991 to 999 mean 0.1 to 0.9 mm.)
    • 006 = 6 mm (6 liters / m²)
  • t = reference period in which the reported precipitation fell
    • 2 = 12 hours


7wwWW (example: 72186)

  • 7 = Identifier for weather condition and course
  • ww = weather condition at the time of observation or during the last hour
    • 21 = at the time of observation no reportable weather phenomenon, but rain during the last hour
  • WW = the weather over the last few hours
    • 86 = Rain during the last six hours: short rain showers followed by prolonged rain


8NCCC (example: 82842)

  • 8 = identifier for the cloud group
  • N = amount of low or medium-high clouds in eighths of the visible sky area
    • 2 = 2 eighths (2/8)
  • C (CL) = type of low-level clouds
  • C (CM) = type of medium-high clouds (clouds, mid-level)
    • 4 = lenticular altocumulus clouds ( Altocumulus lenticularis)
  • C (CH) = type of high clouds (clouds, high-level)

(If the clouds cannot be seen due to fog or darkness, for example, a slash (/) is reported for CL, CM, CH.)

(See also: Detailed explanation of the encryption of clouds )


9GGgg (example: 91150)

  • 9 = identifier for the observation time (in UTC time)
  • GG = hour
    • 11 = 11 a.m. ...
  • gg = minute
    • 50 = ... and 50 minutes


The above explanations only fit the given SYNOP code, here the ground weather report of a land station. There are other variations and extensions in the code that would go beyond the scope of this page.

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