Chances Of A White Christmas?

 

Environment Canada has provided an analysis of 59 years of weather data (back to the year I was born ) for 43 communities across Canada, which highlights the likelihood of having two or more cm of snow on the ground.   It’s interesting to note that almost all of the cities are now a bit less likely to have a White Christmas than when I was a child.  Only the extreme west and east (Victoria, Vancouver and St. Johns) are now statistically a bit more likely to have a White Christmas (on average).

Since this year (2015) will be the warmest year for the Earth in the past 135 years since records began, it is reasonable to attribute some of this trend to climate change.  In fact, in general, snow amounts have been lower and temperatures have been higher across the country this month… so the chance of a White Christmas in 2015 is actually quite low for many communities.

 

Besides, climate change, we have an abnormally strong El Nino (warm tropical water temperatures in the Eastern Pacific).  As well, sea surface temperatures are also higher then normal (after a warm summer and autumn) along the Atlantic and Pacific coasts.  This is also contributing to the mild start to the winter. Winter solstice is Monday evening (11:49pm EST) or Tuesday morning (12:49am AST ).

 

 

For Christmas Eve, the weather pattern is not a typical El Nino pattern.  In fact, western and central parts of the country will be on the cold side. Victoria, who has gone more than 650 days without accumulating any snow (2cm), does have a chance of getting a covering of snow!  However, in Halifax (and in many places in eastern Canada), there is virtually no chance of a White Christmas, as rain and double digit temperatures are likely Christmas Eve.

The following table charts the amount of snowfall recorded for major cities across Canada from 1955-2013. From this, a probability can be made to determine if a white Christmas will occur for the current year.

­
City	%Chance 1955-2013	%Chance Now 1994-2013	%Chance Before 1965-1984	Perfect Christmas 1955-2007	Snowdepth Now 1994-2013	Snowdepth Past 1965-1984
Brandon	93	90	95	28	19	12
Calgary	58	55	70	4	5	5
Charlottetown	80	60	95	48	10	15
Edmonton	86	80	100	20	13	17
Fredericton	78	55	85	30	8	22
Goose Bay	98	95	100	53	37	64
Grand Prairie	85	80	100	26	18	23
Halifax	58	45	65	24	3	9
Hamilton	63	60	65	26	6	5
Iqaluit	100	100	100	51	18	20
Kamloops	51	45	55	25	5	11
Kelowna	63	50	75	26	4	8
Kenora	100	100	100	43	23	31
Kitchener-Waterloo	70	60	73	45	6	9
Lethbridge	49	45	55	6	6	5
London	69	55	80	33	7	9
Medicine Hat	56	50	75	17	5	6
Moncton	75	70	80	40	12	21
Montreal	78	70	85	25	9	17
Ottawa	81	75	85	35	19	18
Prince George	92	85	100	40	15	20
Penticton	29	20	35	11	2	4
Quebec	98	95	100	60	25	45
Regina	92	90	95	38	15	14
Saint John	61	45	70	36	4	12
Sarnia	61	40	85	19	4	7
Saskatoon	95	85	100	22	11	12
St. John’s	64	65	50	24	8	9
Sault Ste Marie	81	80	95	69	18	24
Stephenville	83	70	90	64	16	22
Sudbury	95	90	100	46	20	21
Sydney	61	40	65	46	5	9
Thunder Bay	97	90	100	38	13	23
Timmins	98	95	100	46	30	48
Toronto City	46	40	50	9	4	4
Toronto(GTA)	53	40	65	13	4	5
Vancouver	10	15	5	4	4	1
Victoria	10	15	5	6	3	0
Whitehorse	100	100	100	27	18	28
Wiarton	83	75	90	54	16	18
Windsor	46	45	50	4	4	3
Winnipeg	98	95	100	11	14	12
Yellowknife	100	100	100	27	25	24

Definitions

• % Chance:  probability of a white Christmas (snow on the ground of 2 cm or more on Christmas morning at 7 a.m. EST) for full period of 59 years
• % Chance Now: for children today based on period 1994-2013
• % Chance Before: for parents today when they were children based on period 1965-1984
• Perfect Christmas: snow on the ground of 2 cm or more on Christmas morning and snow in the air sometime Christmas day, i.e., a measurable snowfall on Christmas based on period 1955-2007
• Snowdepth Now: average depth of snow on the ground (cm) on Christmas morning from 1994 to 2013
• Snowdepth Past: average depth of snow on the ground (cm) on Christmas morning from 1965 to 1984

I am sharing some of this with CBC listeners from a number of stations across the country (see below) on the last day of Autumn (Monday 21 December).  At this point, communities in Atlantic Canada have a diminishing chance of a White Christmas, with Western Canadians more likely to enjoy a White Christmas.

My own assessment is:

• Gander will have a 10% chance or less.  They only have a couple centimetres on the ground, and mild air with rain showers likely overnight Christmas Eve
• Corner Brook will have about a 30% chance.  Some areas have about 15cm on the ground, but rain and mild temperatures are forecast for Christmas Eve night.
• Sydney also has only a 30% chance.  Some spots have 30cm on the ground, but rain and 6C Thursday will be followed by 10C Friday.
• Halifax has less than a 5% chance.  There is only a dusting and mild temperatures and rain are also forecast for Christmas Eve.
• Thunder Bay has about an 80% chance of keeping the 10cm or less they have.  There may be a bit of snow early Wednesday; but along the lake it may change to rain… making a chance of a Green Christmas along the Lakeshore.
• Saskatoon has a 95% likelihood of keeping its 10cm or so of snow on the ground, with additional light snow possible Wednesday as temperatures drop during the week.
• Yellowknife remains cold and has 100% sure thing that the 30cm on the ground will remain.
• Kamloops has about a 80% chance of a White Christmas as the temperature will remain near or below zero this week, and some brief light snow is expected.
• Victoria has about a 30% chance of have some wet flurries Thursday night.

While a white Christmas is nice, a green Christmas can be a welcome benefit to travellers.

Stay safe, Merry Christmas and Happy Holidays.

Jim