Roger Smith

Strong winds also up here, with resultant power failure after trees came down on power lines. Near blizzard conditions in southern Alberta, major highway multi-vehicle pile up north of Calgary. We have lost our thin snow cover during recent mild spell, quite cold in the wind but it cleared up shortly after a couple of brief flurries, still quite windy, 35 F.

Until you see a temp above 47 F, Dec 2025 remains tied with 1917 in first place for lowest max. Sadly that probably won't survive. Today's departure looks like it could push the running anomaly down to around -9 F which will perhaps be the low point for the month. As I was saying yesterday, lots of ups and downs ahead and I would expect this anomaly to be cut in half but -5 to -6 for the month is still possible if there's enough cold in the mix. If the mean after today drops to 32.4 F it will currently be tied with three t-28th coldest Decembers (for the entire month), a finish closer to 36 F seems likely, and the median of all 157 (if below 36.5) will be 36.5 F so there is some chance of the month being in the lower half of all Decembers, something that only happens two or three times a year in the modern and urban-warmed climate. A total of 26 Decembers had a mean at or below 32.0, the only recent ones being 1989 and 2000. By decades it is fairly easy to see the warming of the climate but about half of this is likely due to urban heat island increases. (27th was 1892 at 32.2 and the three at t-28th 32.4 are 1909, 1944 and 1995). Three more (1902, 1921, 1980) were tied at 32.5 F. DECEMBERS WITH MEANS 32.0 OR LOWER (listed by 30-year intervals slightly modified, 1869-1900 (8), 1901-30 (7), 1931-60 (6), 1961-90 (4), 1991-2024 (1). 1871 (29.2), 1872 (28.3), 1876 (24.9), 1880 (26.5), 1882 (30.6), 1883 (32.0), 1886 (29.6), 1890 (29.9) 1903 (31.5), 1904 (30.3), 1910 (30.0), 1914 (31.6), 1917 (25.0), 1919 (30.2), 1926 (28.9) 1935 (30.0), 1942 (31.1), 1945 (31.0), 1955 (29.7), 1958 (29.4), 1960 (30.9) 1962 (31.5), 1963 (31.2), 1976 (29.9), 1989 (25.9) 2000 (31.1)

ORD anomaly for 1st to 15th is -11.3 F.

Looks like Friday's frontal passage (timed for around 0900h EST) could lead to a few hail or snow showers with rapidly falling temperatures? It would be around 45F before the front goes through and low to mid 30s by afternoon in W-NW winds gusting to 35 or 40 mph. Lots of ups and downs in temperature trends now to end of the month, it looks likely to average near normal so the current large negative anomaly would be essentially cut in half (balanced by a zero anomaly for half a month). But it looks very cold near the end of the current GFS run by NYE-NYD.

(cross-posted from general Dec thread) ... to give an idea of climate extremes at this point, current temps in lower MI are 5-10 F so this is a very chilly air mass coming in behind the snow ... I imagine the urban heat island will prevent the 1874 records from being surpassed but 24/12 would not surprise me as temp Sunday afternoon low Monday. It may still be warmer at 0100h Sunday to bump up that day's max, then Monday could see later warm advection spoiling another very low max. But these low max values probably indicate the coldest it has been in the daytime hours. As you'll know, 1917 wasn't done by any means with this cold and snowy outbreak, all-time records fell 29th to 31st and into early Jan 1918 too. The same can be said for 1933. And 1874 was followed by possibly the harshest winter of all, lots of record cold in Feb-Mar 1875. Lowest maxima for Sunday and Monday for NYC DEC 14 _ 21 (1902), 22 (1888), 23 (2010), 24 (2005), 26 (1903,1904), 27 (1898), 28 (1933) DEC 15 _ 20 (1874,1914), 22 (1917), 25 (1871), 26 (1903), 27 (1919, 1962, 2010), 28 (1904, 1905, 1916, 2017) Lowest minima for Monday DEC 15 ___ 8 (1874), 9 (1883), 10 (1914, 1917), 13 (1900, 1902), 14 (1910, 1943, 1962), 15 (1904, 1921) __ 18 (1980, 2005) coldest recent years Heaviest snowfalls 13-14 (2d totals include all > 1.0") (daily records 8.0" 13th 1917 and 5.8" 14th 2003) 1917 _9.5" (8.0+1.5) _2d record for Dec 13-14 1902 _6.1" (6.0" 13th, 0.1" 14th) 1915 _6.0" (5.0+1.0) 2003 _5.8" (all on 14th) 1889 _5.5" (all on 14th) 2013 _5.0" (all on 14th) 1942 _4.1" (all on 13th) 1922, 1945 _3.2" (all on 14th) 1904 _2.8" (on 13th, followed 4.2" on 12th for 7.0" total) 1951 _2.5" (all on 14th) +0.8" 15th = 3.3" total 1933 _2.2" (2.0+0.2) 1995 _1.7" (all on 14th) 1892 _1.5" (all on 13th), 1893 and 1907 _1.5" (all on 14th) 1981 _1.4" (all on 14th) 1923, 2017 _1.2" (all on 14th) _ 2017 added 1.2" 15th for 2.4" total. 1909 _1.0" (all on 13th)

Temps in mid 20s by morning, could be very icy on untreated roads. Could fall as low as 0-5 F in rural areas by midnight Sunday, temp now in parts of lower MI despite daytime heating and lakes being 45 F. I see 498 dm thickness indicated at present there, modifies only slightly heading to coast.

Lowest maxima for Sunday and Monday for NYC DEC 14 _ 21 (1902), 22 (1888), 23 (2010), 24 (2005), 26 (1903,1904), 27 (1898), 28 (1933) DEC 15 _ 20 (1874,1914), 22 (1917), 25 (1871), 26 (1903), 27 (1919, 1962, 2010), 28 (1904, 1905, 1916, 2017) Lowest minima for Monday DEC 15 ___ 8 (1874), 9 (1883), 10 (1914, 1917), 13 (1900, 1902), 14 (1910, 1943, 1962), 15 (1904, 1921) __ 18 (1980, 2005) coldest recent years Heaviest snowfalls 13-14 (2d totals include all > 1.0") 1917 _9.5" (8.0+1.5) 1902 _6.1" (6.0" 13th, 0.1" 14th) 1915 _6.0" (5.0+1.0) 2003 _5.8" (all on 14th) 1889 _5.5" (all on 14th) 2013 _5.0" (all on 14th) 1942 _4.1" (all on 13th) 1922, 1945 _3.2" (all on 14th) 1904 _2.8" (on 13th, followed 4.2" on 12th for 7.0" total) 1951 _2.5" (all on 14th) +0.8" 15th = 3.3" total 1933 _2.2" (2.0+0.2) 1995 _1.7" (all on 14th) 1892 _1.5" (all on 13th), 1893 and 1907 _1.5" (all on 14th) 1981 _1.4" (all on 14th) 1923, 2017 _1.2" (all on 14th) _ 2017 added 1.2" 15th for 2.4" total. 1909 _1.0" (all on 13th)

<<< LOWEST DECEMBER MAXIMUM TEMPERATURES >>> Rank __ Year __ Temp _ 01 ____ 1917 __ 47 (1st) _t02 ____ 1872 __ 49 (15th), 1876 _ 49 (13th), 1880 _ 49 (5th), 1890 _ 49 (3rd), 1926 _ 49 (14th) _t07 ____ 1874 __ 51 (3rd), 1882 _ 51 (6th), 1904 _ 51 (28th) _t10 ____ 1909 __ 53 (6,13,14), 1944 _ 53 (8th), 1955 _ 53 (3rd), 1989 _ 53 (31st) (was 2nd lowest 48 before that) _t14 ____ 1903 __ 54 (13th), 1910 _ 54 (30th), 1945 _ 54 (8th), 1997 _ 54 (16th) _t18 ____ 1871 __ 55 (23rd), 1883 _ 55 (8th), 1886 _ 55 (24th), 1888 _ 55 (17th), 1902 _ 55 (22nd) ___ ___ t18 __ 1933 _ 55 (25th), 1958 _ 55 (5th), 1963 _ 55 (8th), 1976 _ 55 (7th), 1985 _ 55 (2nd, 24th), ___ ___ t18 __ 1995 _ 55 (3rd), 2005 _ 55 (24th) _t30 ____ 1907 __ 56 (10th), 1929 _ 56 (14,15,19), 1935 _ 56 (9th), 1974 _ 56 (8th), 1977 _ 56 (14th) _t35 ____ 1870 __ 57 (4th), 1894 _ 55 (12th), 1896 _ 57 (13th), 1898 _ 57 (30th), 1907 _ 57 (23rd), ___ ___ t35 _ 1915 _ 57 (18th), 1922 _ 57 (1st), 1943 _ 57 (9th), 1959 _ 57 (13th) _t44 ____ 1887 __ 58 (11th), 1892 _ 58 (8th), 1913 _ 58 (3rd), 1920 _ 58 (14th) ___ ___ _t44 _ 1925 _ 58 (5th, 6th), 1930 _ 58 (1st), 1942 _ 58 (2nd), 1947 _ 58 (3rd), 1948 _ 58 (13th), ___ ___ _t44 _ 1961 _ 58 (5th), 1981 _ 58 (2nd), 2003 _ 58 (13th), 2019 _ 58 (10th) _t57 ____ 1877 __ 59 (20th), 1884 __ 59 (31st), 1893 __ 59 (16th), 1899 _ 59 (11th,12th), 1900 _ 59 (24th), ___ ___ t57 _ 1905 _ 59 (3rd), 1906 _ 59 (31st), 1921 _ 59 (1st)1952 _ 59 (11th), 1957 _ 59 (20th), ___ ___ t57 _ 1972 _ 59 (31st), 1983 _ 59 (12th, 13th), 1986 _ 59 (3rd), 2004 _ 59 (8th, 23rd) ================================================ Up to 1910, it was normal for December to fail to break 59 F, it happened in 30 of 42 years (71%). From 1911 to 1960 it happened 23 more times (46%). From 1961 to 2000 it happened 13 more times (33%). From 2001 to 2024 it happened 4 more times (17%). (2003,04,05,19) Overall it has happened 70 times (45%). The interval 2006 to 2018 (13 Decembers) is the longest interval without a sub-60 maximum value. Before that, the longest such interval was ten years (1964 to 1973) and before that six years (1936 to 1941). The average value for all years is 60.3 F. Since 1961 the average is 62.2 F. Since 1990 it is 62.9 F.

<<< HALL OF SHAME DECEMBER SNOWFALLS >>> (with rest of seasons) Winter ____ OCT _NOV _DEC _JAN _FEB _MAR _APR ___ TOTAL 1877-78 ___ 0.0 __ Tr ___ 0.0 __ 6.1 __ 2.0 __ 0.0 __ 0.0 __ _ 8.1 _ 1882-83 ___ 0.0 _14.0 ___ 0.0 __ 9.4 __10.2 _ 10.0 __0.5 _ _ 44.1 _ 1891-92 ___ 0.0 __ Tr ___ 0.0 __12.2 __ 0.1 __12.0 __ 1.0 _ _ 25.3 _ 2006-07 ___ 0.0 __ 0.0 __ 0.0 __ 2.6 __ 3.8 __ 6.0 __ Tr _ _12.4 _ 2011-12 ___ 2.9 __ 0.0 __ 0.0 __ 4.3 __ 0.2 __ 0.0 __ 0.0 _ __ 7.4 _ 1885-86 ___ 0.0 __ Tr ___ Tr ___13.5 __ 5.3 __ 1,.0 __ 1.0 _ _ 20.8 _ 1888-89 ___ 0.0 __ 1.5 __ Tr ___ 4.0 __ 7.0 __ 4.0 __ 0.0 _ _ 16.5 _ 1895-96 ___ 0.0 __ Tr ___ Tr ___ 3.0 __ 9.5 __30.5 __3.0 _ _ 46.0 _ 1936-37 ___ Tr ___ 3.2 ___Tr ___ 6.5 __ 3.4 __ 2.5 __ Tr __ _ 15.6 _ 1943-44 ___ 0.0 __ Tr ___ Tr ___ 4.8 __ 7.7 __ 4.8 __ 6.5 _ _ 23.8 _ 1953-54 ___ 0.0 __ 2.2 __ Tr ___12.7 __ 0.5 __ 0.1 __ 0.3 __ _ 15.8 _ 1965-66 ___ Tr ___ 0.0 __ Tr __ 11.6 __ 9.8 __ Tr ___ 0.0 _ _ 21.4 _ 1971-72 ___ 0.0 ___ Tr ___ Tr ___2.8 _ 17.8 __ 2.3 __ Tr __ _ 22.9 _ 1972-73 ___ Tr ___ Tr ___ Tr ____ 1.8 __ 0.8 __ 0.2 __ Tr __ __2.8 _ 1994-95 ___ 0.0 __ Tr ___ Tr ___ 0.2 __11.6 __ Tr __ Tr ___ _ 11.8 _ 1996-97 ___ 0.0 __ 0.1 __ Tr ___ 4.4 __ 3.8 __ 1.7 __ Tr __ _ 10.0 _ 1997-98 ___ 0.0 __ Tr ___ Tr ___ 0.5 __ 0.0 __ 5.0 __ 0.0 _ __ 5.5 _ 1999-2000_ 0.0 __ 0.0 __ Tr ___ 9.5 __ 5.2 __ 0.4 __ 1.2 _ _ 16.3 _ 2001-02 ___ 0.0 __ 0.0 __ Tr ___ 3.5 ___Tr ___ Tr ___ Tr __ __ 3.5 _ 2015-16 ___ 0.0 __ 0.0 __ Tr ___27.9 __ 4.0 __0.9 __ Tr __ _ 32.8 _ 2018-19 ___ 0.0 __ 6.4 __ Tr ___ 1.1 ___ 2.6 _ 10.4 __ 0.0 _ _ 20.5 _ 2022-23 ___ 0.0 __ 0.0 __ Tr ___ Tr ___ 2.2 ___0.1 __ 0.0 _ _ 2.3 _ 2023-24 ___ 0.0 __ Tr ___ Tr ___ 2.3 __ 5.2 ___ Tr __ 0.0 _ _ 7.5 _ 1899-1900_ 0.0 __ Tr ___ 0.1 ___ 1.0 __ 6.6 __ 5.9 __ Tr __ _ 13.6 _ 1900-01 ___ 0.0 __ 0.0 __ 0.1 __ 2.0 __ 7.0 __ Tr ___ 0.0 _ __ 9.1 _ 1931-32 ___ 0.0 ___2.0 ___0.1 ___0.8 __ 1.8 __ 0.6 __ Tr _ __ 5.3 _ 1954-55 ___ 0.0 __ Tr ___ 0.1 ___ 2.6 __ 5.2 __ 3.6 _ 0.0 __ _11.5 _ 1974-75 ___ 0.0 __ 0.1 __ 0.1 __ 2.0 __10.6 __ 0.3 __ Tr ___ _ 13.1 _ 2021-22 ___ 0.0 __ 0.0 __0.2 __15.3 __ 2.0 __ 0.4 __ 0.0 _ _ 17.9 _ 1906-07 ___ 0.0 __ 1.0 __ 0.3 __11.0 _ 21.8 __13.3 __ 5.8 _ _ 53.2 _ 1913-14 ____0.0 __ Tr ___ 0.3 __ 1.3 __17.4 __21.5 __ Tr __ _ 40.5 _ 1918-19 ____0.0 __ 0.0 __ 0.3 __ 0.3 __ 0.5 __ 2.7 __ Tr __ __3.8 _ 1941-42 ___ 0.0 __ 0.0 __ 0.3 __ 6.4 __ 1.9 __ 0.5 __ 2.2 _ _ 11.3 _ 1988-89 ___ 0.0 __ 0.0 __ 0.3 __ 5.0 __ 0.3 __ 2.5 __0.0 _ __ 8.1 _ 1977-78 ___ 0.0 __ 0.2 __ 0.4__20.3 _23.0 __6.8 __ Tr __ _ 50.7 _ 1992-93 ___ 0.0 __ 0.0 __ 0.4 __ 1.5 _ 10.7 _11.9 __ 0.0 _ _ 24.5 _ 2012-13 ___ 0.0 __ 4.7 __ 0.4 __ 1.5 __12.2 __ 7.3 __ 0.0 _ _ 26.1 _ 1978-79 ___ 0.0 __ 2.2 __ 0.5 __ 6.6 _20.1 __ Tr ___ Tr ___ _ 29.4 _ 1986-87 ___ 0.0 __ Tr ___ 0.6 __13.6 __ 7.0 __ 1.9 __ 0.0 _ _ 23.1 _ 1937-38 ___ Tr ___ 0.8 __ 0.7 __ 6.5 __ Tr ___ 0.7 __ 6.4 __ _15.1 _ 1991-92 ___ 0.0 __ Tr ___ 0.7 __ 1.5 ___ 1.0 __ 9.4 __ Tr __ _ 12.6 _ 1956-57 ___ 0.0 __ Tr ___ 0.9 __ 8.9 __ 7.0 __ 2.6 __ 2.5 _ _ 21.9 _ 1985-86 ___ 0.0 __ Tr ___ 0.9 __ 2.2 __ 9.9 __ Tr ___ Tr __ _ 13.0 _ 1875-76 ___ 0.0 __ 0.0 __ 1.0 __ 1.5 __ 12.5 __ 3.8 __ 0.0 _ _ 18.8 _ 1905-06 ___ 0.0 __ 0.0 __ 1.0 __ 1.5 __ 6.0 __ 11.5 __ Tr _ _ 20.0 _ 1934-35 ___ Tr ___ Tr ____1.0 __23.6 __ 7.2 __ 2.0 __ Tr _ _ 33.8 _ 2014-15 ___ 0.0 __ 0.2 __ 1.0 __16.9 _ 13.6 _18.6 __ 0.0 _ _ 50.3 _ 1881-82 ___ 0.0 __ Tr ___ 1.3 __ 17.5 __ 9.3 __ 2.8 __ 0.5 _ _ 31.4 _ 1946-47 ___ 0.0 __ 0.0 ___1.3 __ 5.5 __ 17.7 __ 6.1 __ Tr __ _ 30.6 _ 1949-50 ___ 0.0 __ 0.5 __ 1.3 ___ 0.4 __ 8.5 __ 1.4 __ 1.9 __ _14.0 _ 1989-90 ___ 0.0 __ 4.7 __ 1.4 __ 1.8 __ 1.8 ___ 3.1 __ 0.6 _ _ 13.4 _ 1898-99 ___ 0.0 __19.0 __ 1.5 __ 5.3 __25.3 __4.8 __ 0.0 _ _ 55.9 _ __________________________ From this arbitrary cutoff at 1.5" for Dec snow, there are 52 (of 156) winter seasons where Dec snow is less than 1.5" and of those, 23 had no snow or a trace amount and five more just 0.1". A few of those cases had significant snow before December, notably 1882-83 and 1898-99. So there may have been snow on the ground for the first portion of some of these futile Decembers. A few were quite cold or even very cold (1989), so that small amounts of snow would have persisted longer. The interesting thing here is the frequency of nearly snow-free Decembers (0.2" or less, about one in five) and low-snowfall cases (0.3" to 1.5") expanding that to one in three, so it is almost a normal feature of the climate. the Dec average snowfall is clearly influenced by a few heavy falls such as 1947, and the median is probably lower than the mean. Also interesting is a significant number of very good snowfall winters following on, such as 1898-1899, 2014-2015, 1977-1978, and 1913-14. The median seasonal snowfall after a hall of shame December is 16.0" which shows that a poor December is often an indicator of a poor winter, but there are plenty of exceptions to inspire some optimism. The number of exceptions increases towards the cutoff point, it seems that 1.0" or more snowfall is not a contra-indication for the chances of an average season eventually.

WHAT? __ trace of snow WHERE? __ on ground WHEN? __ later IMPACTS __ none, dog may sniff at it FUTURE __ bleak in Texas, get out while you still can

It was also quite mild up north here, near 50 F in the Columbia valley (Trail BC) where there is no snow at all, and 45F at my elevation where we still have a bit of snow cover, mostly frozen slush at this point. Driving down the hill into Trail it was evident that the snow line was just below 3,000' asl here. (at the border the valley is down around 1500' asl). It was almost jacket-free mild in the valley and you do see the odd person wearing shorts even in this ski resort area (making a statement of some kind, no doubt). A minor renewal of the major 2021 Fraser valley flood disaster is underway. The Nooksack River which drains the Mount Baker region into Puget Sound had a natural outflow channel before modern times through a flat area near Abbotsford BC known as the Sumas Prairie. There was a natural lake that was drained for intensive agriculture, and of course in very wet seasons that lake tries to fill up, and largely succeeded in Nov 2021. At this point, some water 2 or 3 feet deep has crossed the border, mostly overflow from the Nooksack although there are some tributaries of the Fraser that flood also. There is some infrastructure to channel these overflows into drainage canals that are then pumped over a low divide into the Fraser. In Nov 2021 the Fraser was also flooding so this failed leading to a very rapid inundation to a level of 10-15 feet in some areas. This potential has been known for decades and you would think massive infrastructure would have been built to deal with it, but for whatever reason we are stuck with the rather ineffective smaller scale plans that only work in moderately wet weather conditions. This is because our BC provincial politics seem to be based on a combination of salmon worship and endless talk about possible plans but not starting any of them for fear of offending the spirit of the wild bear. At least that's how it was explained to me at the Indoctrination Center.

Two Decembers that flipped very greatly from cold first half (+2-4 days) to mild second half would be 1875 and 1895. The means changed as follows: 1895 ___ mean 1-17 30.7 ___ mean 18-31 47.7 ___ overall 38.4 1875 ___ mean 1-20 29.1 ___ mean 19-31 41.3 ___ overall 33.4 The largest upward shifts in recent Decembers are 2003 ___ mean 1-21 34.5 ___ mean 22-31 44.2 ___ overall 37.6 2005 ___ mean 1-22 32.0 ___ mean 23-31 43.2 ___ overall 35.3 The most prolific change was in Dec 1895 and most of the rest of the winter (Jan-Mar 1896) turned quite cold again. Winter 1875-76 remained mild well into Feb 1876, March was cold.

If history repeats, with the 1946 record highs for today, it is just one year and sixteen days to the monumental blizzard of 2026.

Least favorite type of weather here, cold rain falling on snow and slowly turning it to slush. About 5" of snow on ground yesterday is now basically 3" of gloop. Not so bad above 4,000' so far, ski resort slopes are mostly up higher than that. Around 37 F at my elevation, mid-40s and mostly bare ground lower down in Columbia valley.

Presumably the tracked component began on Oct 27 and its motion is prograde at low latitudes so the closer it gets to the center of the circle, the closer to the equator it has tracked. The current location is where the red portion of the track begins (on Dec 5 as posted). The labels around the outside of the graph show that the frame of reference is as follows ... left is around 60 deg W longitude (tropical N Atlantic near Trinidad), bottom is around 30 deg east (east Africa), right is 120 deg E (w Indonesia) and the top of the square is 150 W (south of Hawaii). The component being tracked (almost always a generally prograde motion from west to east, you can see one brief retrograde period labelled early Nov) is anomalous tropical convection. The MJO assumption is that this will anchor the dynamics of the higher latitude ridge-trough pattern that drives the jet stream in the mid-latitudes. So to sum up, the diagram tracks the motion of this forcing over about two months with 45 past days and 15 future days projected. In this case the feature has crossed the equatorial Pacific and moved across at least part of central America where it has begun to drift closer to the equator. It is progged to continue that motion for 2-3 days and then slowly reverse back towards the subtropics. There is no longer-range projection shown but one could assume the later December into January track would take it across Africa into the Indian Ocean. But I don't follow it myself, just aware of what others think it may mean to long-range prospects. Because it's not my main focus I may have some of these details wrong, so perhaps somebody more familiar with the diagram can set us straight. I think the phrase Maritime Continent is a reference to the many islands of Indonesia and the Philippines as well as Australia and New Zealand in general terms. What I would not swear to is that the diagram is meant to convey equal differentials of longitude, it may be somewhat schematic on that, and the scale of the latitude range is not really clear but I assume the circle is the tropic of Cancer and the center of the diagram is the equator. It would probably be rare for the tracked component to get to any latitude much greater than 25 N.