April 14th is the anniversary of Titanic‘s collision with an iceberg in the North Atlantic. The event occurred at 41° 46′ N and 50° 14’ W, almost the most southerly location on record (Figure 1). One can’t absolve the sailors from lack of vigilance because the accident happened, but it’s important to know their situation and expectations.Figure 1: Chart showing known locations of ship collisions with icebergs
Red crosses mark collisions, but also outline “Iceberg Alley”. It’s where pieces of ice calve from the west coast of Greenland and drift south with the Labrador Current. Iceberg numbers and extent are determined by changing climate, which affects glacier dynamics, water and air temperatures, and ocean currents. Figure 2 shows the Labrador Current flowing to a confrontation with the North Atlantic Drift. When the Gulf Stream is off the New England coast, it’s driven east by the prevailing westerly winds. The boundary between the cold, dark, bottle-green waters of the Labrador Current and the light blue, almost turquoise of the warm tropical waters is a very sharp visible boundary. I saw it many times while chasing Soviet submarines around the North Atlantic. The diagram show the cold dense water deflecting the warmer water and affecting the trajectory toward western Europe.Figure 2: Labrador Current and North Atlantic Drift
As far as is known using dead-reckoning navigation, Titanic was on course. Figure 2 shows the point of collision was at the southern limit of the Labrador Current. Icebergs melt as they move south and most are totally melted or very small at this latitude. Therefore it’s an area the crew wouldn’t expect icebergs, especially one large enough to sink them.
Why did such a large iceberg get that far south in 1912? Study of the weather patterns provide explanation. Media reports tell the story and are all summarized in this statement:
The 1912 United States cold wave (also called 1912 cold air outbreak) remains one of the coldest winters yet to occur over the northern United States.
January, 1912 was the coldest on record for Norfolk, NE, at -39°C and Pennsylvania State College weather station recorded -30°C on the night of January 11th. This was reinforced by a comment from a Canadian newspaper,
What made the winter of 1912 a record-breaker was not the absolute cold – 1934 was worse – but that it settled in quickly and stayed put.
So it was a prolonged cold spell, a point confirmed by another source.
It started in December 1911 and continued into late February 1912. February and March continued the unrelenting freeze. Both months were unusually cold, and March was the coldest on record for many states in the Midwest and Northeast. Parts of North Dakota saw their coldest March readings to date. Some cities saw their coldest weather that winter since the Little Ice Age. 1912 itself was a very cold year.
These conditions indicate a very deep prolonged outbreak of cold arctic air across central and eastern North America that became a “blocking” high pressure system. Persistence of the pattern resulted in severe weather or prolonged weather in other regions. All are characteristic of a Meridional Pattern of flow in the Circumpolar Vortex (Jet Stream) in Figure 3.Figure 3: Meridional Pattern of the Rossby Waves. Source: Author
In England, the general weather pattern was notable because of cool wet conditions;
The almost complete absence of summer weather and the frequent rains at almost all seasons have rendered 1912 memorable. The bad weather was more noticeable by contrast with the magnificent weather of 1911.
Dull and Wet. Mild Winter. Very Cool late Summer and Autumn.
March was a very changeable month as a series of Atlantic weather systems crossed the country.
In Regina, Saskatchewan, in central Canada the weather was equally significant.
Known as the Regina Cyclone, this storm has been rated an F4 on the Fujita Scale based on reported damage and historical photographs. To date, it is the deadliest tornadic storm in Canadian history, taking 28 lives and leaving more than 200 injured.
All this confirms that a very deep northerly flow of cold arctic air persisted over eastern North America. This would drive cold Labrador Current water further south carrying the icebergs with it. The cold air reduced above water ablation of the icebergs. Confluence of the cold arctic water and warm tropical water make the region south of Newfoundland the foggiest region in the world. Conditions in 1912 enhanced the fog forming potential that further hampered the lookouts. This was the final event in a sequence of weather conditions that resulted in a terrible maritime disaster.