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A Scientific FAQ for a Personal Weather Station

A sourced station FAQ: display units, siting, derived indices, and why a backyard reading differs from the airport. Not folklore and not an NWS warning desk.

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A useful station FAQ answers three families of questions: what the numbers mean (units), where they were taken (siting), and why they do not match the airport. Each answer is a sourced explanation a visitor can use. Rotating unsourced “fun facts,” state-extreme folklore, and implied forecasts do not belong here. A personal weather site is not a warning desk.

The historical TNET Weather URL /weatherfaq.php pointed at a file of short blurbs that other pages displayed as random quotes, including Arizona climate anecdotes. That is a knowledge-base problem for a notebook, not an FAQ. This article rebuilds the page as question-and-answer. TNET Weather does not operate the historical Mesa backyard as a live station and does not replace the National Weather Service.

Historical context

Operators wanted one URL for repeat questions: units, “is this official,” “why isn’t this the airport.” Neighboring pages also shuffled climate one-liners through footers. Mixing those modes is how an FAQ becomes folklore. The weather-facts notebook covers rotation. This page answers.

What units does this site use?

Whatever the website configuration says it displays. A complete answer names temperature, wind, rain, and pressure units in one block and says whether pressure is station pressure or a reduction to sea level. WMO observing practice is SI-first. U.S. public weather communication often uses mixed customary units (degrees Fahrenheit, miles per hour, inches, hectopascals or inches of mercury). Either system is fine when it is consistent. Switching wind to knots on one panel and miles per hour on another is not a scientific compromise; it is a template error.

If you are comparing two sites, convert explicitly. Do not argue in mixed units.

Is the thermometer in the shade? Why does siting matter?

Air temperature is defined as the temperature of the air at the instrument, in a shield that limits solar radiation error, over a surface that is supposed to represent the local environment. WMO guidance in the Guide to Instruments and Methods of Observation (WMO-No. 8) exists because nearby roofs, pavement, walls, and exhaust bias that reading. A fan-aspirated shield reduces some radiation error. It does not cancel a rooftop or a parking pad.

The visitor sheet at /weather-info.php should say, in ordinary language, where the shield sits. Distances, heights, and siting class belong on station configuration as scientific metadata. If those pages are silent, the FAQ should say the exposure is not documented—not invent “carefully placed.”

Wind is more demanding. Standard meteorological wind is a 10 m measurement over open terrain. A rooftop anemometer measures rooftop flow. Both can be honest observations. They are not interchangeable.

Precipitation is reduced by wind undercatch and by obstacles that shelter the gauge. A collector next to a wall is not the same instrument as an open gauge at standard height.

Why does this reading differ from the airport?

Because it is a different instrument in a different place, at a different height, over a different surface, often with a different averaging period. That is the entire answer. The rest is mechanism.

U.S. airports typically report through Automated Surface Observing System (ASOS) or similar official suites. NWS ASOS documentation describes a standardized airfield installation: prescribed sensor heights, a standard wind mast, aviation-oriented sky and visibility instruments, and observation rules for aviation and synoptic users. Official city climate is often that airport series, not a backyard.

A personal station is usually none of those things. Documented reasons contemporaneous readings disagree:

  • Location and surface. A few kilometers of desert, irrigation, or urban fabric is real climate. Asphalt, roof membrane, and turf store heat differently; the sensor measures its immediate environment.
  • Height. A 1.5–2 m backyard shield and a rooftop probe are different exposures. Wind at eave height is not 10 m airport wind.
  • Shield and averaging. Naturally ventilated hobby shields overheat more readily in sun and light wind than a well-sited, aspirated official sensor. ASOS wind and gust have defined averaging; comparing a PWS peak gust to a two-minute mean is a category error.
  • Maintenance and derivation. A dry fan, dirty funnel, or wireless dropout is operations, not meteorology. Sea-level pressure, heat index, and dewpoint are calculated. Comparing a “feels like” to ASOS air temperature is not a temperature comparison.

Agreement is interesting. It is not proof the backyard matches official climate. WMO siting classification exists partly to say how far a site is from a reference exposure. A rooftop site can be right for a local question and still be a poor stand-in for the airport record.

For official observations and climate, use NWS and NCEI. For the backyard series, use the backyard series with its metadata attached.

What is heat index, dewpoint, or “feels like”?

They are derived, not extra thermometers.

Dewpoint is determined from temperature and humidity (psychrometric relations). Heat index is an apparent temperature the NWS computes from temperature and humidity after Steadman (1979) and the operational Rothfusz regression; the NWS heat-index equation is the public operational statement. Wind chill is a different apparent-temperature formula for cold, windy conditions. “Feels like” on consumer software is often a vendor blend. If the template does not name the formula, treat the number as unlabeled derived output.

None of these is a forecast. None is a warning. NWS heat-related and wind-chill products, when issued, live on weather.gov.

How often is the data updated? Is it “live”?

Live means the latest published packet with a disclosed observation time. It does not mean the browser animation is a sampling theorem. Logger interval, upload interval, and page refresh are three clocks; website configuration should name them. If the observation time is an hour old, the honest page shows a gap, not a spinning needle.

Is this an official forecast? Can I use it for freeze or flood decisions?

No. A PWS publishes observations from listed instruments and, sometimes, a third-party forecast product in a side panel. The issuing authority for U.S. public forecasts and warnings is NWS. Probability of precipitation, winter weather warnings, flash flood warnings, and heat products have official definitions. A backyard rain total of 0.00 in next to a radar thumbnail is not a warning decision. Use weather.gov and local emergency authorities. TNET is not a warning service.

Why don’t rain totals match the television or the airport?

Storms are patchy. A cell can wet the airfield and miss a yard a few kilometers away, or the reverse. Gauges also differ in height, shielding, splash, and heating. Television graphics are often mosaics or model-based estimates, not your funnel. Compare rain only with the accumulation period named (since midnight, storm total, water year) and with the understanding that one gauge is one point.

Who operates this site, and is it still the historical station?

This FAQ is documentation on a preserved historical URL. Place, elevation, and sensor list belong on the information sheet. Do not treat recovered 2005 coordinates as current without a dated update. TNET Weather is an independent weather-research and connection-intelligence service. It is not SpaceX, Starlink, or NWS.

Outbound scientific links are curation, not FAQ. The documentation cluster is mapped on the section landing. This page does not shuffle unsourced extremes, diagnose vendor firmware, or disclose proprietary TNET scoring rules.

Practical checklist for operators writing an FAQ

  1. Limit public questions to units, siting, airport differences, derived indices, update cadence, and authority.
  2. Cite WMO or NWS; do not paraphrase a forum.
  3. Point at the info sheet and siting record instead of duplicating coordinates.
  4. Label observed, derived, and forecast where the distinction matters.
  5. Send hazards to weather.gov in the same sentence that says this site is not official.
  6. Refuse folklore, even as local color; date the FAQ when siting or units change.

Modern relevance

The airport-versus-backyard question is the public form of representativeness: which environment did the sensor actually measure. Connection-intelligence work asks an analogous question of weather evidence—what was observed, what was modelled, what was derived—and refuses to collapse those into one unlabeled number. TNET’s plain-language account is how the service works. Provenance and quality-control language for public records is data sources, quality controls, and methodology.

Related: weather-station hub, visitor information sheet, hardware siting metadata.

Sources