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Post by Nidaros on Dec 12, 2020 11:23:00 GMT -5
As the title says, and please state what your criteria is.
IMHO a proper White Christmas has snow lying on the ground, not just a few flakes in the air that melts the second it hits the ground.
But if that is what you have data for, then snow falling is also interesting in this thread.
It can be Christmas Eve (Dec 24.), as we here in the Nordics most often use, or Christmas day (25. Dec).
It can be your locations, or any location that is of interest.
Also, please state the altitude, as that is important information.
Our met-office has been so kind to give a lot of data on their website just recently, with 1991-2019 as normal period. Also the snow depth last Christmas, 2019.
So here is a few places in Norway, chance of snow on the ground on the morning of Christmas Eve (Dec.24th).
Oslo (94m, Blindern): 60 %. In 2019: 0 cm on the ground (snowless)
Oslo (360m, Bjørnholt): 83 %. In 2019: 37 cm
Hemsedal (648 m): 100 %. In 2019: 71 cm
Kristiansand (151m, Mestad): 40 %. In 2019: 0
Bergen (12m, Florida): 23 %. In 2019: 0
Voss (316m, Øvstedal): 90 %. In 2019: 7 cm (Voss is inland from Bergen)
Trondheim (23m, Leinstrand S of the city): 70 %. In 2019: 4 cm (Trondheim AP Værnes: 57 %)
Røros (685m, Aursund): 100 %. In 2019: 49 cm
Vesterålen (8m, Alsvåg): 67 %. In 2019: 4 cm
Tromsø (100m, met.office): 90 %. In 2019: 52 cm.
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Post by Steelernation on Dec 12, 2020 13:51:08 GMT -5
29% chance here at 5004’ (1525 m).
That’s either snow lying or snow falling.
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Post by Benfxmth on Dec 12, 2020 14:38:11 GMT -5
The historical probability of a White Christmas is 2% at 16 ft elevation here, based on the map nei posted.
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Post by Ariete on Dec 12, 2020 14:45:09 GMT -5
FMI's criteria for a white Christmas is at least 1 cm on the ground at 8:00 on the 24th or/and 25th.
Turku 91-19
Both days white: 1991, 1993, 1995, 1996, 1997, 1999, 2001, 2002, 2003, 2004, 2005, 2009, 2010, 2012, 2014, 2018
One of two days white: 1998
Both days black: 1992, 1994, 2000, 2006, 2007, 2008, 2011, 2013, 2015, 2016, 2017, 2019
Therefore, the chance of a white Christmas is: 59%.
Biggest snow depth has been on Christmas Eve 2003 with 39 cm on the ground.
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Post by knot on Dec 12, 2020 14:50:28 GMT -5
I don't believe in superstitions such as "Christmas", so 0%.
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Post by MET on Dec 12, 2020 14:54:44 GMT -5
0% chance. I don't use the ridiculous Met Office definition as being a flake of snow on some arbitrary building or whatever. Basically a white christmas for me is when there is lying snow on the ground on the day. Simply enough it won't happen, and if there are some snow flurries that won't count either so basically 0% chance here.
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Post by nei on Dec 12, 2020 15:24:23 GMT -5
the national weather service has a clickable, zoomable map based on 30 year normals; big changes in a small difference in elevation and going north. Amherst is 45%, Greenfield looks like the low 50s. White Christmas = at least one inch of snow on the ground. You can see the topography well on the map www.climate.gov/news-features/featured-images/are-you-dreaming-white-christmas downstate NY is only 10% |
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Post by Wildcat on Dec 12, 2020 15:49:57 GMT -5
10% according to the map nei posted.
Taking all years on record on NOWData, there’s a 16% chance of >= 1 inch snow depth.
The last time there was snow on the ground on Christmas was 2010.
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Post by Volodymyr Zelenskyy on Dec 12, 2020 16:40:28 GMT -5
In Idyllwild area between 25 and 40%
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Post by Deleted on Dec 12, 2020 17:26:27 GMT -5
London has a 4% chance of snow or sleet falling on Christmas Day.
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Post by Crunch41 on Dec 12, 2020 17:40:40 GMT -5
From the map nei posted, 50 percent chance of snow cover. Weather stations range from 37% in the far southeast to 98% near the northern border with Michigan. Two weeks out, most of the state is snow-free and so is the UP. The southern area with snow just appeared today.  |
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Post by jgtheone on Dec 12, 2020 23:21:16 GMT -5
0% of course. Probably something miniscule like 0.05% in the alps, however.
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Post by Morningrise on Dec 13, 2020 0:00:10 GMT -5
Based on Environment Canada's definitions, Saskatoon has a 94% chance of a White Christmas (at least 2cm of snow on the ground on the morning of Dec 25th) and a 34% chance of a "Perfect Christmas" (White Christmas with further measurable snowfall occurring during the day). As our winters have gotten milder, the probability of a White Christmas has dropped however. The numbers above are based on 63 years of climate data, and the probability went from 100% in the first half of that period to only 85% in the second half. Likewise the average snow depth has dropped by 2cm. White Christmas stats for many Canadian cities: www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/historical-christmas-snowfall-data.html#label2 |
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Post by Nidaros on Dec 13, 2020 9:45:37 GMT -5
So here is a few places in Norway, chance of snow on the ground on the morning of Christmas Eve (Dec.24th). Oslo (94m, Blindern): 60 %. In 2019: 0 cm on the ground (snowless) Oslo (360m, Bjørnholt): 83 %. In 2019: 37 cm Hemsedal (648 m): 100 %. In 2019: 71 cm Kristiansand (151m, Mestad): 40 %. In 2019: 0 Bergen (12m, Florida): 23 %. In 2019: 0 Voss (316m, Øvstedal): 90 %. In 2019: 7 cm (Voss is inland from Bergen) Trondheim (23m, Leinstrand S of the city): 70 %. In 2019: 4 cm (Trondheim AP Værnes: 57 %) Røros (685m, Aursund): 100 %. In 2019: 49 cm Vesterålen (8m, Alsvåg): 67 %. In 2019: 4 cm Tromsø (100m, met.office): 90 %. In 2019: 52 cm. As winters have warmed during the last 30 years, I also calculated the chance for at least 1 cm snow on the ground on Dec 24th for the last 15 years (2005-19) for my location. Trondheim (Leinstrand) then had snow on the ground 9 years, giving a 60 % chance. Trondheim-Værnes had measurable snowdepth 5 years, so 33 % chance. Largest snow depth in 2010, with 37 cm at Leinstrand and 43 cm (!) at Værnes. 2010 was something special, even Bergen recorded 26 cm snowdepth on Christmas Eve. Only 2 years with snow on the ground in Bergen last 15 years, so 13% chance. |
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Post by AJ1013 on Dec 13, 2020 9:52:17 GMT -5
Between 0.013% and 0.026% here in Miami. Around 3% in Tucson.
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Post by nei on Dec 13, 2020 10:02:59 GMT -5
Between 0.013% and 0.026% here in Miami. Around 3% in Tucson. you've had 1 inch of snow stick on the ground in Key Biscayne?! |
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Post by AJ1013 on Dec 13, 2020 10:05:09 GMT -5
Between 0.013% and 0.026% here in Miami. Around 3% in Tucson. you've had 1 inch of snow stick on the ground in Key Biscayne?! I’m assuming white christmas means falling snow. 1” of snow is impossible. For Tucson, since I’m lazy, I just used # of christmases with accumulating snow of any amount (4), 2 of which had more than an inch stick. |
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Post by Deleted on Dec 13, 2020 10:07:23 GMT -5
White Christmas in most places means snow falling.
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Post by nei on Dec 13, 2020 10:11:31 GMT -5
White Christmas in most places means snow falling. OP uses snow on the ground; the US national weather service (from my link) uses snow on the ground with a 1" threshold; snow falling seems to be the British definition |
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Post by nei on Dec 13, 2020 10:15:37 GMT -5
As the title says, and please state what your criteria is. IMHO a proper White Christmas has snow lying on the ground, not just a few flakes in the air that melts the second it hits the ground. But if that is what you have data for, then snow falling is also interesting in this thread. It can be Christmas Eve (Dec 24.), as we here in the Nordics most often use, or Christmas day (25. Dec). It can be your locations, or any location that is of interest. Also, please state the altitude, as that is important information. Our met-office has been so kind to give a lot of data on their website just recently, with 1991-2019 as normal period. Also the snow depth last Christmas, 2019. So here is a few places in Norway, chance of snow on the ground on the morning of Christmas Eve (Dec.24th). Oslo (94m, Blindern): 60 %. In 2019: 0 cm on the ground (snowless) Oslo (360m, Bjørnholt): 83 %. In 2019: 37 cm Hemsedal (648 m): 100 %. In 2019: 71 cm Kristiansand (151m, Mestad): 40 %. In 2019: 0 Bergen (12m, Florida): 23 %. In 2019: 0 Voss (316m, Øvstedal): 90 %. In 2019: 7 cm (Voss is inland from Bergen) Trondheim (23m, Leinstrand S of the city): 70 %. In 2019: 4 cm (Trondheim AP Værnes: 57 %) Røros (685m, Aursund): 100 %. In 2019: 49 cm Vesterålen (8m, Alsvåg): 67 %. In 2019: 4 cm Tromsø (100m, met.office): 90 %. In 2019: 52 cm. would have expected much lower for Trondheim. Trondheim's December mean is -1.3°C; about the same as NYC (0.0°C). NYC has a 10% chance, Trondheim 57%. Must be from precipitation falling far less often as rain there in December and low variability and sun. |
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