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Adjusted Humidity Readings

We are now adding 6% when humidity readings reach 94% since that is the maximum our sensor will read. For many years Davis Instruments’ sensors have struggled to achieve 100% humidity. Unfortunately, the problem seems to worsen with time. When we placed our sensor in service last November 28th, it would reach 98%.

Also, we are adding 1% to 92% (to make 93%) and 3% to 93% (to make 96%) to reduce the jump between 91% and 100%. Tests demonstrate these adjustments achieve our accuracy goal of +/- 3%.

You may occasionally see other readings besides 93%, 96%, and 100% due to 5 minute averaging of humidity values.

Raw values are available on the stats page.

Here’s some more info on this problem if you’re interested:

We have a backup weather station for emergencies. It also contains a Davis VP2 station with an SHT31 sensor inside that is less than 2 years old. It maxes out at 96% humidity, but it also has an average +8% bias below 80% which worsens as temperatures climb into the 80s and 90s. So it has a wet bias in the middle and a dry bias at the top. Keep in mind that the maximum error for this sensor is supposed to be 3.5% according to the manufacturer.

We are not the only ones to experience these issues. Many other Davis VP2 weather station owners have reported them (in a thread approaching 1200 posts). Davis says they are “looking into it”, although that was almost 2 months ago now. Some particularly brave souls have attempted to informally wire up older and/or unsupported sensors (SHT75) with varying degrees of luck. We’re not keen on performing ad hoc experiments with our primary temperature/humidity sensor. Some combination of Murphy’s Law and common sense would argue that such slapdash “solutions” will inevitably break at the worst time. Indeed our various attempts with other sensors on the test bench have not gone well. Therefore, we await a viable, proven fix preferably from Davis Instruments.

Noticed Some Changes Lately?

Last week I tweaked the color scheme to match the forecast icons. We’re keeping with the sky/water/sand theme only now just a bit brighter and more coherent.

Today, I removed the weather history icons that lived beneath the current conditions. Nobody was clicking on them. The images accounted for about 1/3rd of the data necessary to load the home page. That wasn’t a good tradeoff between useful information and bandwidth consumption. I’m always mindful that people have limited data on their mobile plans. Speed is another concern too.

I also moved the dropdown selector that was in the conditions section to the page settings (gear wheel icon in the upper right of home page). That’s where it belongs rather than cluttering up the current conditions. If you need to change the frequency of updates, it’s just one click to get there. Again, the data shows that few people adjust that setting, so why not put it where power users naturally go anyway?

One more tiny detail. I added the time zone to the conditions and forecast update times. When visitors travel, they shouldn’t have to wonder if the times listed are local time or Marquette time. The forecast will always be updated in Eastern time. The conditions will be updated according to the current time zone selected on your computer or mobile device. In Marquette, they should both show “EST” or “EDT” depending on Daylight Saving Time.

Also, I should mention that we recently changed hosts about 3 weeks ago. Regular, long-time visitors may remember some extended outages lasting hours, even days in one instance last year due to some lackluster planning by our old host, A2hosting. I picked out another Michigan hosting company, Liquid Web.  Not only do they own their data center in Lansing (rare), but their operation is prepared to withstand power & internet failures, weather events, and DDOS attacks (coordinated hacking) among other unfortunate events. That’s not to say the site will never go offline, but, hopefully, not as frequently or for as long. It’s much more expensive to host with them, but their speed and reliability so far have been phenomenal.

Well, thanks for visiting. If you enjoy the site, please tell your friends & family!

What Happened To The Forecast?

The website’s featured forecast provider, Weather Underground (WU), announced a change in policy last month. They were no longer going to allow free, limited access to their raw forecast data (API). Instead, they would begin charging hundreds per month even to those who contribute data like we do. Since this site generates no revenue, the new price tag is a nonstarter.

I’ve been exploring alternatives in hopes of continuing to offer dual forecasts. None of them have met my requirements of accuracy and affordability. Therefore, I’ve decided the National Weather Service (NWS) will be the sole forecast provider for marquetteweather.com.

In addition, the hourly forecast will not be replaced due to problems inherent in the forecasting process. Presently, the software-based weather models do not adequately represent the transient effects of the Great Lakes frequently leading to significant errors exceeding our forecast target of +/- 3 degrees. Plus, the forecasts don’t update often enough to keep pace with our weather. Routine changes in wind direction, cloud cover or precipitation can transform conditions in a matter of minutes — as most Marquetters intuitively understand.  Continue reading “What Happened To The Forecast?”

A New Stats Page is Born!

Synopsis: we are archiving the city’s climate and presenting it to the community in what we believe is an accessible and easy-to-read format.

Perhaps you’ve visited the Statistics page previously. WeatherCat, the software that grabs data from the weather station, automatically generated those numbers and even uploaded them to the website.

Well, the old saying “if it’s easy, it ain’t worth doing” proved true, unfortunately. As time went on, I kept spotting more mathematical errors. Plus, the tables were not very readable. Visitors couldn’t access daily history after 60 days. Navigating the page was difficult too.

Over a month ago I began overhauling the page. This involved taking raw data directly from the database and programming  complex mathematical formulas. Smoke may have occasionally emanated from the computer (not to mention my ears!). Continue reading “A New Stats Page is Born!”

Temperature Readings Just Improved!

Custom Davis radiation shield

There was a Problem?

So perhaps you’ve noticed lately on sunny days forecasted highs have been lower than the actual highs by several degrees. Well… it turns out that’s not entirely true.

During the deepest part of winter when the polar vortex was regularly occurring (late December into January), we were having equipment issues. Normally, we measure temperatures inside an enclosure that has a fan running on solar power during the day and batteries at night. Unfortunately, the weather destroyed the electronics that controlled the battery charging, among other casualties.

As a quick fix, we installed a passive (fan-less) shield for our sensor. Passive shelters are fine during our normally very cloudy, windy winters. Wouldn’t you know it, the sun decided to show up and, along with it, gentle breezes! That makes for beautiful winter days in Marquette. It is also a recipe for solar-induced sensor errors.

The snow acts like a mirror to the sun and the reflected radiation gets into the sensor and heats it up. How much? A rough estimate, based on before and after tests of running with and without a fan, is 3-5 degrees F. Studies have shown that, in fact, on completely calm, sunny days over a fresh blanket of snow, errors can reach up to 18 deg F! Continue reading “Temperature Readings Just Improved!”

Is Marquette Snowier Than We Think?

weather instrumentation facing northwest
Snow board looking NW

Over the last 30 years, the city has averaged 117.2” per year of snow. That’s based on measurements taken every morning close to the lakeshore (at the Waste Water Treatment Plant which houses the official COOP weather station for Marquette, MI).

A few days ago we added a “Seasonal Snow Total” entry to the Almanac section on the home page. This should provide some insight into the kind of winter we are having. Currently, the official weather station is seeing below average snowfall so far (55.1″) while we are experiencing above normal totals (83.6″).

Here at marquetteweather.com, located 1/4 mile south of downtown and approximately 100 ft above the lakeshore, we measure up to 4x daily.  According to the Community Collaborative Rain, Hail & Snow Network (CoCoRaHS), if snow stops falling midday, measuring the next morning can mean up to a 50% reduction in measurement (see below).  Continue reading “Is Marquette Snowier Than We Think?”

Let’s Talk Weather

John & Monique

Welcome to our new blog!

Two and a half years ago my wife and I started this site to provide the community with a free, one-stop weather resource. We felt that the City of Marquette wasn’t being adequately served by the available weather websites and apps.

The site has grown tremendously. We thought it was time to share a bit more and, perhaps, hear from you. The first time you comment, it will be reviewed (to cut down on spam). If approved, future comments will be posted directly to the page without approval.*

Wouldn’t it be nice to have a kind of community water cooler? Everyone loves to talk about the weather!  Continue reading “Let’s Talk Weather”