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A Chilly November… A Chilly Year?

Yesterday, November 13th, the high was 21 (both here and at the official COOP station). The coldest high temperature on record for that day in Marquette was 20 set most recently in 1919 (tied with 1883 & 1900).

We’ve recorded 5 days in row with lows in the teens! Normal lows this time of year in the city are around 30. Normal highs are in the low 40s.  So far we are running more than 6 degrees below normal for the first 14 days of November. That follows a cold October.

If the forecast holds, it looks like there will be a slight bump in temps today, tomorrow, and Friday, although still not quite “normal”. Then we drop right back into well below normal temps for the weekend and the beginning of next week.

The Trend for 2018?

It’s been an up and down year so far, but we are all but guaranteed to end the year below normal  — barring a record setting December.* The question is by how much?

Let’s put this into the context of the past few years. In 2017 the yearly average temperature was 43.5 (when data is adjusted to match the same period of observation employed by the COOP station). That’s almost half a degree below normal.** 2016 was about 1.4 degrees above normal. We don’t have a complete data set for 2015; however, the official station reported 0.7 degrees below normal that year. Assuming our current trend of -6.1 degrees holds for November and December is completely normal, we would end 2018 about 1.7 degrees below normal. To end 2018 above normal would require November to completely erase it’s 6 degree deficit in the remaining 14 full days followed by a December that was 14+ degrees above normal!

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NOTES:

* An earlier version of this article incorrectly stated that we were likely to end 2018 well below normal for the year (-3.5 degrees potentially). After discovering an error in the supporting math, I have softened the prediction. Additionally, I have revised the calculation method to match the measurement period of the official COOP station (an observation period of 8AM – 8AM in which each month starts and ends at 8AM the last day of the month). Note that the average temperatures reported in the yearly table on our weather history page are calculated by calendar days and months. We can do that since our station is automated. Whereas the COOP station has manually observed daily temperatures once per day using a minimum-maximum thermometer (in the mornings since about 1960 and in the afternoons before that) for over 140 years!

** First we take the normal yearly average temperature over the last 30 years as measured at the Waste Water Treatment Plant, the official weather station for Marquette, which is 43.1. Then we determined the average difference between our station and the official station for every month of the year since August 2015 (listed in our weather history “normals” table under the “Depart” heading). That averages out to +0.76F. Or, put simply, 43.1 + 0.76 = 43.86 which rounds to 43.9. This preliminary number will improve over time as we collect more data. 

When Weather Apps Fail at Weather

I wrote about this yesterday on Twitter. Given the limitations of that platform, however, I couldn’t really go deep. Let’s dive in.

Here are two screenshots taken within 60 seconds yesterday afternoon:

 

The 1st image is of a popular weather app recently redesigned for the iPhone. The 2nd image is our universal web app loaded in Safari on an iPhone.*

Continue reading “When Weather Apps Fail at Weather”

Demolish Marquette to Improve Forecasts?

Would forecasts improve if we removed all the buildings, ripped out all the concrete and moved everyone to tents situated along Lakeshore Blvd? Short answer: likely.

Too often the forecasted high temperatures for Marquette run well below the measured high temperatures, especially on sunny days when the wind isn’t blowing off the lake. This is true of all forecast agencies I’ve observed to one degree or another. It just so happens the local National Weather Service, our forecast provider, is also guilty of this trend. Continue reading “Demolish Marquette to Improve Forecasts?”

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?”