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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.

Jan ’21: Warm & Dry & A Somewhat Clear Sky

Marquette just recorded its least snowy January on record (1857 – present)! The official station at the Water Treatment plant recorded a mere 3.5″. Normally, we receive almost 30″.

Melting that snow and combining it with whatever ice and rain also fell, amounted only to 0.77″. That’s less than half the 30 year normal amount of 1.83″.

Also, the mean monthly temperature of 24.7° in January ties for 8th on the list of all time warmest with 1878.

Here at our station near the Jacobetti Home for Veterans, we recorded 10.4″ of snowfall (0.72″ of liquid) in January. Whereas the last 3 winters we averaged 29.4″.

Our station’s monthly mean temperature (as measured from 8 AM to 8 AM and rounded to whole numbers) was 23.9°. That’s +5.5° compared to our station’s normal.

Continue reading “Jan ’21: Warm & Dry & A Somewhat Clear Sky”

Record Cold in Marquette

Following 2 days of highly unusual lake-effect snow (8″ recorded at our station), Marquette saw it’s coldest October 27th in recorded history. NWS Marquette has confirmed that the low of 20° this morning set at the COOP station near the lakefront broke the old record of 22° set back in 1887.

October is running about 5° below normal. As of the morning of 27th, this is the 19th coldest October on record (since 1857). Finishing in the top 20 certainly appears doable if the forecast holds.

Overall, we’ve had a cool (meteorological) autumn so far as September was also a couple degrees below normal.

We’ll just have to see what the winter brings. It could all turn on a dime next month. But at least the weather’s never boring in the U.P.!

No More Snow Measurements

Unfortunately, I have decided to discontinue snow measurements. Last winter finally persuaded me of the limits of collecting and tabulating daily snowfall — even on a double city lot. The wind eddies around nearby structures result in huge drifts when winds gust upwards of 40 mph. As Marquetters know, this is an all too common event in the winter, particularly when storms come off Lake Superior. It then becomes very difficult or even impossible to separate drifted from newly fallen snow. Sometimes the snow boards are simply blown clean. Taking measurements from multiple locations won’t improve matters when everywhere around is subject to the same forces.

Continue reading “No More Snow Measurements”

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