Expanded Hourly Forecast Now Available

The graphical hourly forecast on the CITY page now looks ahead 48 hours (previously only 24 hours). This should be particularly helpful during long-lasting storm events.

Accuracy beyond 72 hours is lacking in hourly forecasts. 48 hours seems to be the sweet spot now in terms of accuracy and usability. Beyond that, one is forced to scroll through endless tiles looking at information that is going to change significantly in the next 12-24 hours.

The hourly (yellow) & daily (light blue) forecasts are scrollable on mobile devices, trackpads, and mice. On touchscreens, just swiping left will allow you to scroll into the future. On Mac trackpads — same thing — use 2 fingers and swipe left over forecast icons. On PCs and desktop Macs, you need to position the cursor over the forecast tiles and then hit shift and use the mousewheel (scroll up to go forward in time and down to go backward). You can also navigate using a keyboard by pressing tab, then return/enter (to skip the navigation and go straight to the content area), and then press tab repeatedly until it highlights the hourly forecast area. Then you can use the directional arrows.

The End of Snowfall Measurements

When things get bad (2019)

Sadly, we won’t be providing snowfall measurements any longer. It has proven too difficult on our urban property to keep the plowed & drifted snowfall separate from the measurement area. We tried our best to overcome siting issues with multiple boards and locations. Too often, however, particularly during wind-driven storm events, the measurements turn into guesses. We need more open space.

Consider also the practical challenges that twice-daily measurements present in the winter. The observer (me) better not be sick or traveling.

Ultimately, the cost was too great while the benefit — long-term data on snowfall in the city — could not be realized.

I figured it’s best to pull the plug on it at the end of the calendar year.

We started measuring snowfall in the fall of 2017 and have 6 complete years (2018-2023) of weather history data. Detailed snow measurement reports for Fall 2019 – early Winter 2023 can be found in our Snow Measurement Archives.

I will still be providing daily liquid precipitation measurements year round for our weather history records. In the winter this involves melting snow to its liquid equivalent amount.

Alternatively, you can always view official snow observations for the city by visiting NOAA NOWData and selecting “Marquette, MI” as the “Location”, “Daily data for a month” as the “Product”, selecting the current month under “Options” and pressing “Go”.


Mobile Devices Now Have Bottom Navigation

Mobile view with navigation icon
“Off canvas” navigation in a mobile viewport

Previously, if you wished to navigate the website in a mobile device you needed to go (back) up to the top left navigation menu. As of today, if you have scrolled to the bottom of the page, you can simply access the navigation in the footer. This has always been the case for those using PCs & Macs.

New footer navigation as seen in a mobile browser

I had struggled to preserve the navigation in smaller viewports without it appearing cramped in that space… until now. I will leave the “Back to Top” links in place for those who want a quick way to start over from the top of the page.

Also I have added a light blue background color to distinguish this section from surrounding content. In night mode, the footer will turn to a deep navy.

As always, the site is completely responsive which means you can view it on any modern device with the screen size/orientation of your choice. You can even put it in a small browser window when using a computer alongside your other app(s). Home page conditions will update every minute by default and the entire page will refresh every 10 minutes.

I invite you to make full use of the site. Each page is a collection of freely-available, unique resources not found in one space elsewhere.

As it stands we have decent site engagement. That said, plenty of folks — even longtime regular users — have never left the home page. I assure you, we don’t put filler pages on the site. It’s all useful!

Improved Humidity Algorithm

We’ve noticed for awhile that the top value for humidity readings seems to be in the low to mid 90 percentiles (in unadjusted raw values). The humidity sensor’s effective ceiling has dropped since we last performed a significant top-end adjustment in 2020.

Perhaps you’re thinking, “why not just replace the sensor?” Because a new sensor, while perfectly affordable and somewhat more accurate in very moist air, has other more unpredictable errors which will not be easily correctable. I base this assertion upon years of experience with the SHT31 sensors, particularly when exposed to fan-assisted air movement (~2.25 m/s). A replacement sensor need to “harden” in the field for years before being deployed. We’ve had one “baking” in our backup station since last fall, and it’s not ready yet. It’s only to be used in the event of a failure of the primary station.

In the early morning hours of Monday July 24th our location experienced significant dewfall. Dew coated all objects within view, including the housing of our weather station. Unfortunately, our station’s max humidity reading that morning was 91%. Not good. A fan-aspirated weather station, such as ours, will sometimes run a bit drier than nearby air-ventilated stations which are susceptible to moisture depositing within their housing & on sensors when winds are low but air is not quite saturated (95-100% RH).  But given the level of moisture observed combined with empty radar images & precipitation gauges, our sensor should have read upper 90 percentiles at least, with or without a fan to move air through the housing. Other nearby weather stations were reporting maximum humidities for hours, including our backup station.

After hunting through humidity records this past year and observing patterns, I have tweaked the “dry bias” algorithm that progressively adjusts readings above 85% relative humidity. It’s a bit tricky because the sensor also has a “wet bias” that stretches into the low 80 percentiles. Certain values have to be transitioned to make the handoff at 85 smooth yet accurate. Luckily, I’ve got lots of data available from past and present checks against our reference psychrometer (accurate to +/- 1% RH) to aid in the process.

You should now clearly notice when fog, dew or significant precipitation events occur just by examining humidity tables on our weather history page. Future maximum values should be close to, if not precisely, 100%.

Questions? Thoughts? Hit the comment form below.


UPDATE 7/27/23 2:55 PM: Fog descended on Marquette last night! It lasted for several hours. A decent rain storm followed this morning which re-saturated the air with moisture (nearby stations all at max humidity). The new algorithm couldn’t have performed better!!

A Slight Change To The Almanac

Perhaps you’ve noticed the field “Monthly Departure” in the Almanac on the City page (home page)? Its value represents the current aberration from the 30-year normal average temperature for the calendar month.

Previously, this field was being calculated on a month-to-date basis. That meant that if, for example, only 2 days had passed in the month, and those first two days were very hot or very cold, then the departure value would be quite large (either negatively or positively).

As of today we are calculating the departure as a full month preloaded with normal average temperatures. We replace each day’s normal average temperature with an observed daily average temperature as it occurs. This results in much smaller departures earlier in the month.

We feel this updated methodology is a more accurate representation of reality where trends emerge gradually. Climate, by definition, is the general tendency of observed phenomena — in this case temperatures — to occur within certain boundaries over a long-term period. A few days, or even a week, does not determine the outcome of an entire month.

So, to demonstrate…. The first 4.5 days of June 2023 have been unseasonably warm and yet have only resulted in a +1.4° departure (which rounds down to +1°) for the month. We are no longer assuming there will not be 25 days to come. Instead, we put in normals for those remaining days and witness how much our recent weather skews the entire month.

A couple hundred lines of code have gone into this single field (“Monthly Departure”) in the Almanac. This is the sort of thing that sets this website apart from other weather sources.

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