Tom Thomson's Black Spruce in Autumn from 1915

 Black Spruce in Autumn, 1915, (cold frontal passage)

Thomson applied two layers of coloured "ground" on the panel before he painted this view on the western shore of Canoe Lake. Tom wanted this record of weather to last. That portion of the lake is relatively shallow with numerous stumps and rocks. I suspect that Tom simply beached his canoe on some obstacle and painted from a very low vantage point looking upward into the sky.  A cold front with showers had just passed through Tom’s location and he probably felt compelled to paint since the rain would have prevented him from doing so. How do we know all of this? 

Black Spruce in Autumn, Fall 1915
Oil on composite wood-pulp board
8 9/16 x 10 9/16 in. (21.7 x 26.8 cm) (Tom's Paintbox size)
McMichael Canadian Art Collection, Kleinburg (1966.14) 

I first studied this painting in the mid-1990s and was told that considerable funds were required to include any of Thomson's art in my book "Tom Thomson Was A Weatherman". The sums certainly added up and were well beyond my means. As a result, I constructed a blurred image on which I could label what Tom saw and painted.  Apparently, Tom's art is now in the public domain, a hundred years after his passing in 1917. Being a meteorologist and not a lawyer, I am not certain what "being in the public domain" really means. I simply wish to share Tom's passion and reveal why he painted what he did while respecting the laws of the land. 

Tom painted all of the weather clues very clearly and 
in plein (plain) sight. Being a meteorologist certainly helps. 

What we know. The point form layout of these facts reveals the analysis and diagnosis process applied during CSI - Creative Scene Investigation. 

• The low horizon at the lowest third of the panel, identifies this painting as another skyscape.
• The deciduous trees were full of autumn colour, so this sketch's timing must be in later September or October. The colours in Algonquin tend to reach a peak in late September. 
• The clouds were towering cumuli that were very vertically developed and more than tall enough to produce locally heavy rain showers. 
• The tops of the towering cumulus clouds were tilted from right to left consistent with westerly or northwesterly wind shear. 
• Daytime heating in an unstable air mass is the most likely cause of these towering cumuli which are also referred to as cumulus congestus. As a result, we can rule out a warm frontal system which would have been accompanied by cirrus and other warm frontal layered cloud associated with a warm conveyor belt. 
• Otherwise there was only patchy altocumulus in the sky.
• It would take most of the day to develop this scale of instability from daytime heating in the autumn so the daily timing of this sketch was mid to late afternoon.
• The towering cumulus appeared to be organized along a line which could be a simple surface trough or a cold front. Given the time of year, I would expect that a cold front would be required to produce a cloud line like this that was so fully developed.
• There was no sun glint on the lake so Tom is definitely not looking toward the sun as typically anticipated for plein air painters. 
• The trees in the foreground are dark and in shadow, so Tom’s view must have a southerly component.

Another view of Tom's Black Spruce in Autumn so you can 
relate the points to his brush strokes part way through the CSI.

• The clouds are well-illuminated and not backlit so Tom must be looking a bit more to the southeast. For the clouds and distant deciduous tree line to be so well illuminated, both the distant shore and cloud line must have an orientation toward the west and the late afternoon sun. 
• The distant shoreline tends to get smaller and more distant from left to right.
• The tallest clouds along the convergence line tend to be to the right. This is typical for convection along a cold frontal line where the largest and most intense convective cloud tends to be the last one in the line – tail end “Charlies”. These taller towering cumuli are most likely to produce a “passing shower” as they have access to higher values of heat and humidity - fuel for the stronger towers of convective cloud.  
• Note that some of the clouds are darker indicating that they are composed of larger cloud droplets. These larger cloud droplets grow at the expense of smaller cloud droplets. This process takes time and thus these clouds are probably older. These older clouds have probably already precipitated. 
• The wave action was significant even with the limited fetch from the west. The northwesterly surface winds must have been significant.
• The surface winds would be veered slightly  (turned clockwise from a satellite vantage) due to friction compared to the direction of the upper winds revealed by the clouds. 

A map is required to show how this geometry works out. Tom's sketch reveals interesting variations in the orientation of the main elements.

Tom's southerly view with the dark trees,
the shoreline with deciduous trees,
towering cumuli with rain showers, the yellow sun and 
the associated surface wind directions.

An example of similar towering cumuli that Tom would 
have viewed on that 1915 autumn afternoon in Algonquin.

The Most probable CSI Solution

An active (anabatic) cold front had just passed Tom’s painting location. Possible brief but heavy showers and a wind shift to the west would have marked the cold frontal passage. Ahead of the cold front, it would have been warmer and more humid for a fall day. Behind the front, it was going to become cooler, drier, and windier. Simply, Tom painted the back flank of a cold front that had just crossed Canoe Lake.

Black Spruce in Autumn by Thomson from 1915 and on
another October day in 2016 when I paddled Canoe Lake

On a magical day in October 2016,  I was all alone on Canoe Lake. The weather forecast of torrential rain kept the people away. I quietly paddled every nook and cranny looking for Tom and I saw his plein air sketches at every turn. The deformation zone held the rain at bay until 3 pm by which time I was putting my canoe on the car. Sometimes it pays to be a weatherman. 

It was a very special day gently stroking my canoe with the memory of a friend I had never met although knew very well. I saw 49 paintings that day and they can be found in my "Canoe Lake Collection" on Fine Art America.  I may have followed in the footsteps and the paddle strokes of Tom Thomson but I have to paint my own way.

The science clearly hidden in the oils and brush strokes of Tom Thomson is sound. But no one can be absolutely certain. I was not there painting with Tom as much as I would have loved to be. It is important to keep an open mind and that is how we learn - even from our mistakes. 

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick 

PS: For the Blog Version of my Tom Thomson catalogue raisonné, Google Search Naturally Curious "Tom Thomson Was A Weatherman - Summary As of Now" or follow this link “http://philtheforecaster.blogspot.com/2022/10/tom-thomson-was-weatherman-summary-as.html”