Your station on WxAlerts

WxAlerts ingests CWOP and amateur weather stations off APRS-IS, alongside METAR/ASOS and NDBC marine data. Roughly 11,000 CWOP and amateur stations are drawn on the live map, and the observations behind the weather API are composed from the same population.

So this page is the other half of the deal: if you follow the rest of this section and put a station on CWOP, here is exactly what we do with it.

How your station gets here

You do not register with us, and there is nothing to configure. Two things happen on their own once you are on CWOP:

Position comes from the MADIS roster, not from your packets. That means a newly registered station is positioned and known here before any of its packets have been seen. A station in the registry with no reading yet is a real state on our side, not an error.

Readings arrive off APRS-IS under source: aprs, which covers CWOP and amateur radio weather stations together.

This is why registering properly matters more than it might seem. Accurate coordinates and elevation in the CWOP metadata are what put your station in the right place on our map, independent of whatever your software is sending.

Finding yourself

CWOP and amateur stations do not get their own prerendered page, because the networks publish no station name, so a page per station could say nothing but a callsign and a temperature, under URLs that rot as volunteers come and go. They resolve through one lookup route instead:

https://wxalerts.org/stations/lookup/?id=DW9876

That resolves your id against the live API and shows current conditions and observation history, the same view a METAR station gets. Your station’s popup on the live map links there too.

How your data is weighted

When the API composes conditions for a point, it treats every network as one population ranked by distance, age and trust. Your station competes in that ranking. Three things decide how it does.

Trust tier

A tier is a distance penalty, not a veto. At tier 4 your station has to be more than twice as close as an ASOS to win a field. That is the honest position described in why put a station on CWOP. A back-garden console is not half as good as an ASOS, but it is not as good either, and in most of the country being twice as close is easy, because the nearest ASOS is at an airport 40 km away.

Age

Readings decay. The effective distance doubles by the two-hour mark, so an hour-old reading from 2 km beats a fresh one from 20 km, but loses to a fresh one from 3 km. Past two hours a reading is treated as history rather than current conditions and drops out entirely.

Reporting on the standard five-minute cadence keeps you comfortably inside that, with room to miss a cycle.

Dewpoint is computed, not received

A CWOP packet carries humidity and no dewpoint, where a METAR carries dewpoint and no humidity. We derive the missing half of that pair so the two networks are comparable, which means your dewpoint here comes from your humidity sensor. A humidity sensor that has drifted or died shows up as a bad dewpoint as well as a bad humidity.

The consensus check

Some stations lie, and the dangerous case is not noise. It is a stuck or placeholder value. Firmware that sends t000 for “no reading” puts 0 °F on the map in a Florida August, surrounded by two dozen stations reading 82.

Nothing about that reading is out of range. Per-field bounds cannot catch it, because 0 °F is a real temperature in Montana in January. What makes it wrong is its neighbours, so that is what it is checked against: the median of nearby stations. The median, not the mean, because the mean is dragged by exactly the outlier being hunted.

The margin is loose on purpose. This exists to catch broken instruments, not disagreeing ones. A sea breeze front, a thunderstorm outflow or a valley inversion can genuinely put 15 °F between two stations a few miles apart, and all three are real weather worth showing.

Wind and rain are deliberately not checked this way. A gust front or a single cell really does put 30 mph and an inch of rain at one station and nothing at the next one over, and a consensus filter would erase precisely the severe weather we exist to report.

Do and don’t

The short version of this entire section.

Do:

• Register first, then start sending. Registration only completes once packets arrive.
• Report every five minutes, with UTC timestamps in DHM form.
• Send MSLP in the b field, and set your elevation exactly.
• Use dots for missing required fields, in the required order: direction, speed, gust, temperature.
• Site over grass, shield the thermometer, get wind to 10 m if you possibly can, and document your real siting and equipment.
• Watch your Gladstone and MADIS QC, and fix biases. Aim for S or V flags.
• As a ham: -13 SSID, WIDE2-1 path, real passcode, and identify properly.

Don’t:

• Over-report. Faster than five minutes gains nothing and gets you flagged for duplicates.
• Send station pressure as though it were MSLP.
• Use a passcode for a callsign you do not hold.
• Trust citizen wind uncritically, or treat a hobby AS3935 as a sole life-safety trigger.
• Put a temperature sensor on a wall, roof or pavement and call it representative.
• Use WIDE1-1 alone, or long paths, on RF.

Keep your metadata current (coordinates in decimal degrees, elevation in metres, and an accurate equipment description) and email [email protected] when it changes. Accurate metadata is the whole mechanism by which forecasters, and we, can weight your station correctly.

References

APRS specification. aprs.org/doc/APRS101.PDF; aprs.org/aprs11/ (spec-wx.txt, SSIDs.txt); aprs.org/aprs12/weather-new.txt.

CWOP and MADIS. wxqa.com for the FAQ, QC and the current servers list; madis.ncep.noaa.gov for signup and the surface QC notes; registration at findu.com/citizenweather/cw_form.html.

QC and validation. weather.gladstonefamily.net (Weather Quality Reporter); MesoWest at mesowest.utah.edu.

Siting. WMO No. 8, the CIMO Guide; NWS COOP standards.

Software. weewx.com/docs; cumuluswiki.org; the Direwolf user guide and its Weather-Station.pdf.

Sensors. The ams/ScioSense AS3935 datasheet; Sensirion SHT3x and SHT4x; Bosch BME280 and BMP390.

Communities. The groups.io APRS lists; groups.google.com/g/wxqc for CWOP QC and weewx-user; wxforum.net; the Ecowitt and Ambient forums.

Where to go next

• The weather API: reading observations back out, including your own.
• How an alert reaches you: the other pipeline on this site.
• Why put a station on CWOP: back to the start of this section.