Tom Thomson's "Tea Lake Dam" 1917

Many of Tom's paintings places were best accessed by canoe using Canada's first highways. It would have been a leisurely paddle of about 8.5 kilometres from Mowat Lodge to the Old Tea Lake Dam. The runoff and current would have even assisted his paddle in the spring of 1917. The trip might have taken a couple of hours of gentle stroking. The scenery and inspiration would have been breath-taking at every turn. There would have been many distractions along the way. Life like art and canoeing, should not be a race. Enjoy the ride. 

The direct paddle path via (bold yellow line) from Mowat through
Canoe, Bonita and Tea Lakes to the Old Dam that holds all of that 
water back. 

The title simply refers to the Old Dam at Tea Lake. The vantage was just downstream from that dam along the Oxtongue River. The dam controls the water levels of Tea, Bonita, Canoe and Smoke Lakes. The truth is that the painting was all about the weather with the horizon well below the lowest third of the artist's "rule of thirds" grid. The real story not told by the title might surprise you. 

Tea Lake Dam
Spring 1917, 1917.33
Oil on wood panel 8 3/8 x 10 5/16 in. (21.3 x 26.2 cm)
 Tom's paint box size 

What does Creative Scene Investigation (CSI) have in store to tell us? Tom was painting with the afternoon sun on his back on a day which probably began with full sunshine and the promise of a bluebird sky. The morning skies would have been clear and the winds light from the south - a perfect day for a paddle. Unfortunately, there were no convenient shadows available in the painting to precisely time the painting but it takes hours of daytime heating to generate the convection that Tom observed. Any shadows would have been unlikely to see with them trailing away from Tom's view with the sun on his back. 

A 1946 Algonquin Watershed Map illustrating the viewing
direction for "Tea Lake Dam" to the northeast

Creative Scene Investigation Analysis from Tom Thomson Was   
A Weatherman PowerPoint

The story behind the weather is typical for a sunny spring day. 

The clouds which are the subject of his painting were fuelled by the strong spring sun. It was the kind of a day where the recently exposed dark soils of the landscape soak up the sun's energy. Dust devils spinning up 80 kilometre per hour winds are common on such days. 

The moisture from the spring melt was the other fuel source for those low-based convective clouds. Heat and moisture from the surface landscape billow upward within convective bubbles. Those parcels of air cool at a rate defined by the laws of thermodynamics and start to form clouds at the "Lifted Condensation Level"  (LCL) for the air mass. This LCL is the same or at least similar everywhere within the air mass. Note how very close to the ground the level-cloud bases were in Tom's weather observation. Those cloud bases were less than 2000 feet above ground level and the atmospheric dew points would have been higher than 16 degrees Celsius. This reveals that there was a lot of moisture and fuel available for convection that spring afternoon. 

It should come as no surprise that the inscription on the back written by Dr. James MacCallum mentioned a "thundercloud in spring". The oils could not contain the sound of thunder but the cloud structure certainly does. The tell-tale anvil of the cumulonimbus cloud was well outside the edges of the small panel and stretching toward the northeast. The distant cumulus clouds were aligned along the inflow to the storm. The large cloud in the foreground with the dark base was along the flanking line of that spring thunderstorm that had just exited to the northeast. 

The conceptual model for the common multi-cell thunderstorm follows. The flanking line is where new cells develop on the southwestern edge of the multi-cell thunderstorm structure. If Tom was able to paint the thunderstorm as mentioned by MacCallum, the only suitable location was at the western edge of the flanking line after the storm had passed. The prominent cloud featured in Tom's observation would be the "new cell" identified in the conceptual model included below. 

This multi-cell thunderstorm conceptual model is a good summary.
Multi-cell thunderstorms are characterized by multiple updrafts forming
new mature cells as each downdraft (and precipitation) dissipates
the previous cell. Cold air outflow from each dissipating cell
triggers new cells along the leading edge of the flanking line of the
outflow. This thunderstorm type is more long-lived than an ordinary,
 pulse-type, single-cell thunderstorm. Multi-cells are very common in the spring.

A Top-Down View of the Multi-cell Thunderstorm Conceptual Model locating
Thomson's probable vantage at the southwest flank of the thunderstorm
that had just passed their (Thomson and MacCallum ) location. The elements 
included in Tom's composition neatly fit into this conceptual model.

Tom's patron Dr. James MacCallum wrote the inscription on the back of the panel. Those details as recorded required intimate knowledge of the event. There is a reference to finding "a poacher's bag with beaver-skins" in the trees or bushes in the foreground on the right side of the creek. It is unclear whether that was Tom or James who found that bag but the reference that the painting was "sketched just before his drowning" surely refers to Tom Thomson. It certainly sounds as though the good doctor accompanied Thomson on this spring paddle down to the Old Tea Lake Dam.

Tea Lake Dam
Spring 1917, featuring the "new convective cell" on the southwestern
flank of a multi-cell thunderstorm after the storm had passed to the
east over Bonita and Canoe Lakes. Tom painted the natural world
and actual weather events in real-time. 

Inscription verso:

• three graphite sketches of birds (barn swallows?); 
• t., in graphite, Thundercloud in spring at chute where Muskoka River flows out of Lake / looked at from the left side the rush of water and the feeling of daylight is / very marked as well as the feeling of spring - In the trees or bushes in the foreground on right / side of creek I found a poacher's bag with beaver-skins +c - sketched just before his drowning / JMM.;
•  Backing label, Dr James MacCallum
• McMichael Canadian Art Collection, Kleinburg

Tea Lake Dam, Spring 1917 as it would have appeared
in Tom's pochade box

Provenance:

•  Dr. J.M. MacCallum, Toronto 
• Mrs. W.T. Goodison, Sarnia, 1925 
• Mrs. C.A. Lorriman, Sarnia?, by descent 
• Roberts Gallery, Toronto 
• McMichael Canadian Art Collection, Kleinburg, (1970.1.4). Purchased with funds donated by R.A. Laidlaw

Recall that Robert A. Laidlaw was the wealthy friend of Lawren Harris who made the family fortune from the "R Laidlaw Lumber Company". The Laidlaw Foundation founded in 1949 was established with the purpose of providing financial support for charitable, conservation, educational, and cultural organizations in the Ontario region. This explains how "Tea Lake Dam" ended up at the McMichael. The title might be misleading but it does not get in the way of enjoying Tom's observation of the back-side of a multi-cell thunderstorm on a very unstable spring day. 

Warmest regards and keep your paddle in the water,

Phil Chadwick

PS: Tom Thomson Was A Weatherman - Summary As of Now contains all of the entries to date.