barometer-trend

Calculate the tendency and trend of a barometer for a one to three hour period including barometric weather predictions.

Features

• Tendency and trend of the barometer for the last hour or three hours (FALLING|SLOWLY)
• Prediction of weather and systems:
  • By pressure trend only (Expect gale force weather')
  • By pressure trend, thresholds and wind direction (Increasing rain, clearing within 12 hours.)
  • By seasonal pressure thresholds for winter and summer (Cloudy and humid, thunderstorms)
  • Front system tendency for the last three hours (Falling before a lesser rise | Cold front passage | Strong and gusty, then veers)
  • Force wind expectation in Beaufort scale based on the pressure tendency (F8-9)
• Detects current pressure system Low, Normal, High

Note

• Picks the period with the highest severity (one hour or three hours)
• All calculations corrected (internally) to sea level pressure by optional altitude and temperature
• Up to 48 hour history

Install & Use

npm i barometer-trend

const barometer = require('barometer-trend');

barometer.addPressure(datetime1, 101500);
barometer.addPressure(datetime2, 101505);
barometer.addPressure(datetime3, 101512, 100, 20, 225); //100 = altitude, 20 = C degrees, 225 = wind direction 

//barometer.addPressure(...) is more precise when pressure is corrected by altitude and temperature.

let forecast = barometer.getPredictions(); //returns JSON

Note

• Pressure must be input in Pascals, 1015 mBar/hPa = 101500 Pascal.
• getPredictions() investigate the trend for the latest one hour and three hours
• If run less than one hour or three hours, the latest timing up until now is picked.
• The most recent trend with the highest severity is chosen (One hour or Three hour reading)

Contribute

Feel free to contribute; create an Issue, and Pull Request including test code.

Disclaimer

• All calculations is done by online research; the author of this library does not have a background in metereology. All sources listed below.
• A barometer is only one source of weather information and may give a general trend and indication, but not "see" the overall picture. (There's a reason satelittes exists and being a metereologist is a paid job.)
• All calculations presumes being located at sea with no disturbances.
• Near land, winds may be one-two Beaufort scale numbers lower and the wind might be coming from "the wrong direction".
• In subtropic and tropical regions some of the calculations may not be valid at all; i.e. the trade winds (easterlies) is different from northern hemishpere west->east (westerlies) low pressure systems.
• In trade wind zones observe the daily variations; any change to this pattern could possibly indicate gale weather.

Sources / References

• How to use a barometer when sailing
• UK Met Office Marine Forecast Glossary
• Hughes38.com
• SafeBoater.com
• Air pressure changes and their meanings
• Sailing Eurybia
• Wikipedia: Beaufort scale
• Pressure conversion to sea level
• Heidorn.info: Applying The Barometer To Weather Watching