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This example value equals 23.4 °C (74 °F) and 12.3 °C (54 °F). 52006 3-hour pressure tendency. Follows RMK with 5 digits starting with 5. The second digit gives the tendency. In general 0–3 is rising, 4 is steady and 5–8 is falling. The last 3 digits give the pressure change in tenths of a millibar in the last 3 hours.
The airport observations are then transmitted worldwide using the METAR observing code. METAR reports typically come from airports or permanent weather observation stations. Reports are generated once an hour; however, if conditions change significantly, they may be updated in special reports called SPECIs. [9] [10] [11] [12]
The F value (0 to 3) determines the type of descriptor. Element descriptors (F=0): As the name implies, these descriptors are used to convey elemental data and related meta-data. The X value identifies the Class of the descriptor (i.e. Horizontal Coordinate parameters, Temperature parameters, etc.). The Y value is the descriptor's number within ...
Although the first digit or two of the pressure is left off, other nearby stations give away whether the pressure starts with a 10 or a 9. Most of the time, choosing first digits that would lead to a value nearest to 1000 works out best. [5] The plotting of this value within the station model allows for the analysis of isobars on weather maps ...
It is classified as an obstruction to vision in METAR aviation weather observations and is commonly reported if the amount of suspended sand reduces horizontal visibility to 10 kilometres (6 mi) or less. [2] Extreme cases may be called sandstorms. [3] blowing snow
SYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by staffed and automated weather stations. SYNOP reports are typically sent every six hours by Deutscher Wetterdienst on shortwave and low frequency using RTTY .
A TTF is a professionally considered forecast for weather over a two-hour period, [1] and is based on an actual weather report, such as a METAR or SPECI and appended to the end of it. [1] A TTF is similar to or sometimes in addition to a TAF, a terminal aerodrome forecast, but during the TTF's validity period is considered superior to a TAF.
Stations either report hourly in METAR reports, [3] or every six hours in SYNOP reports. [4] These observations are irregularly spaced, so they are processed by data assimilation and objective analysis methods, which perform quality control and obtain values at locations usable by the model's mathematical algorithms. [5]