HIGHS are sometimes reinforced and this results in what is called a stagnant HIGH. A good illustration of such a slow moving HIGH and its consequences occurred during the last week of January, 1922.

A surge of cold air from Alberta or farther north reached the international boundary January 21st and spread slowly eastward, reaching the Great Lakes on the 24th and the St. Lawrence Valley two days later. Then seemingly it halted or moved slowly westward, retrograding. In three days, that is, on the 29th, the centre of the HIGH was apparently 500 miles west of where it had been on the 27th. After the 29th it followed a normal track, moving slowly southeast, reaching the Atlantic near Long Island.

Meanwhile a depression on the south coast of Texas on the 25th, moved across the Gulf of Mexico, passing over Southern Florida on the 27th and advanced steadily northeast, reaching Cape Hatteras in 24 hours. Owing to the presence of the anticyclone referred to above, the depression recurved off Hatteras. The result was a memorable snow storm in Northern Virginia and Maryland. At 8 p.m. January 27th, there had been a fall of 5 cms. (2 inches). Within the following twenty hours the average depth in the city of Washington was 66 cms. (26 inches). The weight of the snow caused the collapse of the roof of the Knickerbocker Theatre and the death of 97 persons.

The total snowfall in various coast cities was:

The table shows clearly how the snow was formed. On the east side of the LOW a stream of air, relatively warm, carried a load of water vapor, approximately 13 grams in each cubic metre.

Fig. 10. Paths of High and Low, Great Snow Storm of January 27-28, 1922]

This current was steered around the north side of the LOW and met the north-northeast wind. Under the new conditions the air saturated could hold only 2 or 3 grams; and so condensation and heavy precipitation resulted. The region of maximum snowfall was near Washington, and it will be seen that there is a proportional decrease north and south. The snowfall at Washington was the heaviest ever known at that city.

Unlike most storms, there was no strong cold northwest wind blowing into the depression. The temperature rose slowly. It was less a contrast of winds than a steady slow outward push of the anticyclone, and the consequent turning of the path of the cyclone eastward.