Files
weather-station/server/src/forecast.mjs
2026-06-27 18:31:44 -04:00

311 lines
14 KiB
JavaScript

import {queryHourly, getCoords, queryCurrent} from './sensors.mjs';
import {getCelestialCurrent} from './celestial.mjs';
import {localDateStr} from './config.mjs';
import {frostRisk} from './openweather.mjs';
export let lastForecast = { ts: 0, slots: [], summary: null }
export const forecastTTL = 5 * 60 * 60_000
function estimatePrecipitation(precipChance, clouds) {
if (precipChance < 30) return 0;
const intensity = (precipChance / 100) * clouds;
if (intensity > 0.7) return Math.round(intensity * 15 * 10) / 10;
if (intensity > 0.4) return Math.round(intensity * 6 * 10) / 10;
return Math.round(intensity * 2 * 10) / 10;
}
function estimateUV(sunElevation, cloudFraction) {
if (sunElevation <= 0) return 0;
const clearSkyUV = Math.sin((sunElevation * Math.PI) / 180) * 12;
return Math.round(clearSkyUV * (1 - cloudFraction * 0.75) * 10) / 10;
}
function linearTrend(values) {
const n = values.length;
if (n < 2) return 0;
const xMean = (n - 1) / 2;
const yMean = values.reduce((a, b) => a + b, 0) / n;
const num = values.reduce((s, v, i) => s + (i - xMean) * (v - yMean), 0);
const den = values.reduce((s, _, i) => s + (i - xMean) ** 2, 0);
return den === 0 ? 0 : num / den;
}
function dewPoint(tempC, humidity) {
const a = 17.27, b = 237.7;
const gamma = (a * tempC) / (b + tempC) + Math.log(humidity / 100);
return (b * gamma) / (a - gamma);
}
function heatIndex(tempC, humidity) {
const T = tempC * 9 / 5 + 32;
if (T < 80) return tempC;
const HI =
-42.379 + 2.04901523 * T + 10.14333127 * humidity
- 0.22475541 * T * humidity - 0.00683783 * T * T
- 0.05481717 * humidity * humidity + 0.00122874 * T * T * humidity
+ 0.00085282 * T * humidity * humidity - 0.00000199 * T * T * humidity * humidity;
return (HI - 32) * 5 / 9;
}
function vaporPressureDeficit(tempC, humidity) {
const svp = 0.6108 * Math.exp((17.27 * tempC) / (tempC + 237.3));
return Math.round(svp * (1 - humidity / 100) * 1000) / 1000;
}
function absoluteHumidity(tempC, humidity) {
const svp = 0.6108 * Math.exp((17.27 * tempC) / (tempC + 237.3));
return Math.round((humidity / 100 * svp * 2165) / (tempC + 273.15) * 1000) / 1000;
}
function pressureRule(trend3h, currentHpa) {
if (trend3h < -2.0) return { label: 'Storm likely', precipitation_chance: 0.85 };
if (trend3h < -0.8) return { label: 'Rain likely', precipitation_chance: 0.65 };
if (trend3h < -0.3) return { label: 'Cloudy', precipitation_chance: 0.35 };
if (trend3h > 1.5) return { label: 'Clearing', precipitation_chance: 0.05 };
if (trend3h > 0.3) return { label: 'Improving', precipitation_chance: 0.10 };
if (currentHpa < 1000) return { label: 'Unsettled', precipitation_chance: 0.30 };
if (currentHpa < 1013) return { label: 'Partly cloudy', precipitation_chance: 0.15 };
return { label: 'Fair', precipitation_chance: 0.05 };
}
function solarTempDelta(sunElevation, cloudFraction) {
if (sunElevation <= 0) return 0;
return Math.sin((sunElevation * Math.PI) / 180) * (1 - cloudFraction) * 6;
}
function nocturnalCooling(cloudFraction) {
return (1 - cloudFraction) * 1.5;
}
function forecastHumidity(absHumidity, forecastTempC) {
const svp = 0.6108 * Math.exp((17.27 * forecastTempC) / (forecastTempC + 237.3));
const rh = (absHumidity * (forecastTempC + 273.15)) / (svp * 2165) * 100;
return Math.min(100, Math.max(0, Math.round(rh * 10) / 10));
}
function estimateClouds(humidity, pressureTrend) {
let base = humidity / 100 * 0.8;
if (pressureTrend < -0.3) base = Math.min(1, base + 0.2);
if (pressureTrend > 0.3) base = Math.max(0, base - 0.15);
return Math.round(base * 100) / 100;
}
function forecastWind(currentWind, pressureTrend) {
const boost = pressureTrend < -1 ? 1.3 : pressureTrend < -0.5 ? 1.1 : 1.0;
return Math.round(currentWind * boost * 10) / 10;
}
export async function get24HourForecast(currentSensors) {
const now = new Date();
const sixAgo = new Date(now - 6 * 3600 * 1000);
const coords = await getCoords();
const history = await queryHourly(sixAgo, now);
const pressures = history.map(r => r.pressure_hpa).filter(Number.isFinite);
const temps = history.map(r => r.temperature).filter(Number.isFinite);
const humidities = history.map(r => r.humidity).filter(Number.isFinite);
const winds = history.map(r => r.wind_speed).filter(Number.isFinite);
const pressureTrend = linearTrend(pressures);
const tempTrend = linearTrend(temps);
const humidityTrend = linearTrend(humidities);
const pressure3h = pressureTrend * 3;
const seedTemp = currentSensors.temperature ?? temps.at(-1) ?? 20;
const seedHumidity = currentSensors.humidity ?? humidities.at(-1) ?? 60;
const seedPressure = currentSensors.pressure_hpa ?? pressures.at(-1) ?? 1013;
const seedWind = currentSensors.wind_speed ?? winds.at(-1) ?? 0;
const seedAbsHum = currentSensors.humidity_abs ?? absoluteHumidity(seedTemp, seedHumidity);
const weather = pressureRule(pressure3h, seedPressure);
let runningAccumulation = 0;
const slots = Array.from({ length: 24 }, (_, i) => {
const time = new Date(now.getTime() + (i + 1) * 3600 * 1000);
time.setMinutes(0, 0, 0);
const pressureDamping = Math.exp(-i * 0.08);
const pressure = seedPressure + pressureTrend * (i + 1) * pressureDamping;
const pressure_slp = Math.round((pressure + (coords.altitude ?? 0) / 8.5) * 100) / 100;
const clouds = estimateClouds(seedHumidity + humidityTrend * i, pressureTrend);
const bgTemp = seedTemp + tempTrend * (i + 1);
const temperature = Math.round(bgTemp * 10) / 10;
const humidity = forecastHumidity(seedAbsHum, temperature);
const wind_speed = forecastWind(seedWind, pressureTrend);
const precipitation_chance = Math.round(weather.precipitation_chance * (1 - i * 0.02) * 100);
const raining = precipitation_chance > 60 ? 'True' : 'False';
const precipitation = estimatePrecipitation(precipitation_chance, clouds);
runningAccumulation = Math.round((runningAccumulation + precipitation) * 100) / 100;
const celestial = getCelestialCurrent(coords.latitude, coords.longitude, time);
const uv_index = estimateUV(celestial.sun_elevation ?? 0, clouds);
return {
time,
temperature,
humidity,
humidity_abs: absoluteHumidity(temperature, humidity),
dew_point: Math.round(dewPoint(temperature, humidity) * 100) / 100,
heat_index: Math.round(heatIndex(temperature, humidity) * 100) / 100,
vapor_pressure_deficit: vaporPressureDeficit(temperature, humidity),
pressure_hpa: Math.round(pressure * 100) / 100,
pressure_slp,
pressure_rate: Math.round(pressureTrend * 100) / 100,
storm_trend: pressure3h < -2 ? 1 : pressure3h > 1.5 ? -1 : 0,
wind_speed,
wind_gusts: Math.round(wind_speed * 1.4 * 10) / 10,
wind_direction: currentSensors.wind_direction ?? 0,
clouds,
raining,
precipitation,
precipitation_chance,
accumulation: runningAccumulation,
uv_index,
uv_dose: 0,
solar_wm2: 0,
daily_light_integral: 0,
lux: 0,
visibility: 50,
...celestial,
};
});
for (const slot of slots) {
if (slot.sunrise && slot.sunset) {
const t = slot.time instanceof Date ? slot.time.getTime() : new Date(slot.time).getTime();
const rise = slot.sunrise instanceof Date ? slot.sunrise.getTime() : new Date(slot.sunrise).getTime();
const set = slot.sunset instanceof Date ? slot.sunset.getTime() : new Date(slot.sunset).getTime();
slot.daytime = t >= rise && t < set;
} else {
slot.daytime = (slot.sun_elevation ?? 0) > 0;
}
const solar = solarTempDelta(slot.sun_elevation ?? 0, slot.clouds);
const cool = slot.daytime ? 0 : nocturnalCooling(slot.clouds);
slot.temperature = Math.round((slot.temperature + solar - cool) * 10) / 10;
slot.humidity = forecastHumidity(seedAbsHum, slot.temperature);
slot.dew_point = Math.round(dewPoint(slot.temperature, slot.humidity) * 100) / 100;
slot.heat_index = Math.round(heatIndex(slot.temperature, slot.humidity) * 100) / 100;
slot.vapor_pressure_deficit = vaporPressureDeficit(slot.temperature, slot.humidity);
slot.humidity_abs = absoluteHumidity(slot.temperature, slot.humidity);
slot.frost_risk = frostRisk(slot.temperature, slot.dew_point, slot.humidity)
slot.solar_wm2 = slot.sun_elevation > 0
? Math.round(Math.sin((slot.sun_elevation * Math.PI) / 180) * 1000 * (1 - slot.clouds * 0.75) * 100) / 100
: 0;
slot.daily_light_integral = Math.round(slot.solar_wm2 * 3600 / 1_000_000 * 4.57 * 100) / 100;
slot.lux = slot.solar_wm2 > 0 ? Math.round(slot.solar_wm2 * 120) : 0;
slot.visibility = slot.clouds > 0.85 ? 10 : 50;
Object.assign(slot, getWeatherCondition(slot));
}
return slots;
}
function groupByLocalDay(slots) {
const days = {}
for (const slot of slots) {
const key = localDateStr(new Date(slot.time))
if (!days[key]) days[key] = []
days[key].push(slot)
}
return days
}
function summarise(slots) {
if (!slots.length) return null
const daytime = slots.filter(s => s.daytime)
const source = daytime.length ? daytime : slots
const avg = (arr) => arr.length ? Math.round(arr.reduce((a, b) => a + b, 0) / arr.length * 100) / 100 : null
const peak = (arr) => arr.length ? Math.max(...arr) : null
const fin = (key) => source.map(s => s[key]).filter(Number.isFinite)
const finAll = (key) => slots.map(s => s[key]).filter(Number.isFinite)
const labelCount = {}
for (const s of source) labelCount[s.label] = (labelCount[s.label] || 0) + 1
const label = Object.entries(labelCount).sort((a, b) => b[1] - a[1])[0][0]
const dominant = source.find(s => s.label === label)
return {
time: slots[0].time,
label: dominant.label,
icon: dominant.icon,
temperature: peak(fin('temperature')),
temperature_max: peak(finAll('temperature')),
temperature_min: Math.min(...finAll('temperature')),
humidity: avg(fin('humidity')),
humidity_abs: avg(fin('humidity_abs')),
dew_point: avg(fin('dew_point')),
heat_index: peak(fin('heat_index')),
vapor_pressure_deficit: avg(fin('vapor_pressure_deficit')),
pressure_hpa: avg(fin('pressure_hpa')),
pressure_slp: avg(fin('pressure_slp')),
pressure_rate: avg(fin('pressure_rate')),
storm_trend: slots.at(-1)?.storm_trend ?? 0,
wind_speed: peak(fin('wind_speed')),
wind_gusts: peak(fin('wind_gusts')),
wind_direction: avg(fin('wind_direction')),
clouds: avg(fin('clouds')),
raining: peak(fin('precipitation_chance')) > 60 ? 'True' : 'False',
precipitation: avg(fin('precipitation')),
precipitation_chance: Math.round(peak(fin('precipitation_chance'))),
accumulation: finAll('precipitation').reduce((a, b) => a + b, 0),
frost_risk: slots.find(s => s.frost_risk !== 'None')?.frost_risk ?? slots.at(-1)?.frost_risk ?? 'None',
uv_index: peak(fin('uv_index')),
uv_dose: finAll('uv_dose').reduce((a, b) => a + b, 0),
solar_wm2: avg(fin('solar_wm2')),
daily_light_integral: Math.round(finAll('daily_light_integral').reduce((a, b) => a + b, 0) * 100) / 100,
lux: peak(fin('lux')),
visibility: avg(fin('visibility')),
sunrise: slots.find(s => s.sunrise)?.sunrise ?? null,
sunset: slots.find(s => s.sunset)?.sunset ?? null,
daylight: slots.find(s => s.daylight)?.daylight ?? null,
moon_phase: dominant.moon_phase ?? null,
moon_illumination: dominant.moon_illumination ?? null,
moon_elevation: dominant.moon_elevation ?? null,
moon_azimuth: dominant.moon_azimuth ?? null,
moon_new: dominant.moon_new ?? null,
moon_full: dominant.moon_full ?? null,
moonrise: slots.find(s => s.moonrise)?.moonrise ?? null,
moonset: slots.find(s => s.moonset)?.moonset ?? null,
}
}
export async function getForecast() {
if (Date.now() - lastForecast.ts < forecastTTL) return lastForecast;
const sensors = await queryCurrent().catch(() => null)
if (!sensors) return lastForecast
const slots = await get24HourForecast(sensors).catch(() => null)
if (!slots) return lastForecast
const days = groupByLocalDay(slots)
const todayKey = localDateStr(new Date())
const todaySlots = days[todayKey] ?? slots
lastForecast = { ts: Date.now(), slots, summary: summarise(todaySlots) }
return lastForecast
}
export function getWeatherCondition(data) {
if(data.lightning_rate > 0 && data.raining === 'True') {
return {label: 'Thunderstorm', icon: '11d'};
}
if(data.raining === 'True') {
if(data.precipitation > 7.6) return {label: 'Heavy Rain', icon: '10d'};
if(data.precipitation > 2.5) return {label: 'Moderate Rain', icon: '10d'};
return {label: 'Light Rain', icon: '09d'};
}
if(data.visibility < 10) return {label: 'Mist', icon: '50d'};
const dayNight = data.daytime ? 'd' : 'n';
const c = data.clouds > 1 ? data.clouds / 100 : data.clouds;
if(c > 0.85) return {label: 'Overcast Clouds', icon: `04${dayNight}`};
if(c > 0.50) return {label: 'Broken Clouds', icon: `04${dayNight}`};
if(c > 0.25) return {label: 'Scattered Clouds', icon: `03${dayNight}`};
if(c > 0.10) return {label: 'Few Clouds', icon: `02${dayNight}`};
return {label: 'Clear Sky', icon: `01${dayNight}`};
}