donsutherland1

Record highs are again tumbling in the South. As of 12 pm EST, Baton Rouge, Galveston, and Pensacola have all set daily record high temperatures. Galveston has had 15 daily record highs and 1 record-tying high. One of those high temperatures set a new December record. 24 of December’s 31 days saw their 1st, 2nd, or 3rd warmest high temperatures for those days.

Some of the guidance is showing that an Alaskan Ridge regime could develop for a time in coming weeks. That typically affords more opportunity for cold. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL085592 The PNA could also go positive late in the first week of January. So, January is looking better than December has been. It might not be severely cold or extremely snowy, but it should be colder and snowier than this December has been.

Not all of Florida. Pensacola is having its warmest December on record.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.6 0.4 -0.1 -2.6 3.0 2.5 -0.5 -0.3 -5.0

Morning thoughts… It will be mostly cloudy with some showers today. It will be unseasonably mild. High temperatures will likely reach mainly the lower and middle 50s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 52° Newark: 55° Philadelphia: 57° Normals: New York City: 30-Year: 40.7°; 15-Year: 41.7° Newark: 30-Year: 41.2°; 15-Year: 42.4° Philadelphia: 30-Year: 42.5°; 15-Year: 43.6° 2022 will begin with unseasonable warmth.

2021 will end with mild conditions. 2022 will begin with more unseasonable warmth. But a turn toward cooler weather lies ahead in the medium-range. In the South, more near record and record heat prevailed. Preliminary records included: Albany, GA: 84° (old record: 80°, 1984) Baton Rouge: 82° (old record: 81°, 1971 and 1984) Galveston: 80° (old record: 75°, 1971 and 2020) Greenwood, MS: 79° (old record: 77°, 1990) Jackson: 81° (old record: 80°, 1923 and 1984) Lake Charles, LA: 81° (old record: 80°, 1934 and 1964) Mobile: 82° (old record: 79°, 1971 and 1974) New Orleans: 84° (old record: 81°, 1990) Pensacola: 81° (old record: 77°, 1971, 1974, and 1996) In addition, Houston recorded its 17th 80° day of this month. The old December record was 10 days, which was set in 2012. Houston also recorded its December record 7th consecutive 80° day. The old record of 5 consecutive days was set during December 3-7, 1998 and tied during December 24-28, 2016. Houston is on track to finish with a monthly mean temperature near 67.8°. That would demolish the longstanding December mark of 64.4° from 1933. It would also be high enough to tie 1909 as the 3rd warmest November on record. January will very likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°). The latest guidance suggests that temperatures could head toward seasonal levels and then below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. Afterward, the cold could press farther south into at least the northern Middle Atlantic and Ohio Valley regions. The colder pattern could last for two or perhaps three weeks before it breaks down. Thus, it could begin to break down sometime in the January 15-20 timeframe. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.25°C and the ENSO Region 3.4 anomaly has averaged -0.98°C. La Niña conditions will likely persist through meteorological winter. The SOI was +15.26 today. The preliminary Arctic Oscillation (AO) figure was -1.158 today. On December 28 the MJO was in Phase 7 at an amplitude of 2.309 (RMM). The December 27-adjusted amplitude was 2.565 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 43.6° (4.5° above normal). That would tie 2021 with 2006 as the 4th warmest December on record.

Without running the climate models, it’s difficult to know. Given what has been established from past attribution studies—longer and more intense patterns—it is likely that December would have been cooler than it will wind up being. With a consistent AO- pattern (but less negative than it has been) during the second half of the month and a reduced SE ridge (due to a weaker PNA-), there may have been more opportunities for snowfall.

Galveston has now recorded its 15th record-tying or breaking high temperature this month. Galveston is also on track to register its 7th consecutive record high minimum temperature.

The reaction to the mention of climate change should not draw negative reactions. Climate change is now well-established scientific theory ("established fact" as the IPCC's technical report termed it). It is not political. Weather events and climate change are inseparable, as synoptic patterns are occurring within the context of increasing greenhouse gas forcing on SSTAs, Arctic ice, etc. Taking consideration of climate change is now essential to understanding the evolution of weather events. Climate change-driven events ranging from the effects of Arctic Amplification to marine heatwaves impact synoptic patterns. "Stuck" patterns or long-duration resonance events have become more frequent (December 2015 in the East, Summer 2021 in parts of the West, and December 2021 in the South provide some examples). Heat has become more frequent, more widespread, and more intense. Severe cold can still occur, but such outbreaks have become somewhat less frequent, less widespread, and less intense. Ignoring climate change and its impacts can lead to bad subseasonal forecasts (often frequent strong cold biases). Reliance on past analogs while ignoring such variables as marine heatwaves and their impact on tropical convection (and through convection on the larger hemispheric pattern) can lead to errors that might otherwise be avoidable when the fuller context of what's driving synoptic patterns is considered.

The extreme cold shifted eastward into western Canada and the Pacific Northwest for a time.

The increasing frequency of significant marine heatwaves is a fairly recent development that renders a lot of past analogs—for those who use them—largely irrelevant. If one recalls, there had been some social media chatter early this month that December 2021 could be compared to December 1995. But some of the major regional SSTAs were wildly different and the PDO was severely negative this time around. Not coincidentally, the 1995 idea did not have merit.

Morning thoughts… It will be mostly cloudy with some showers today. High temperatures will likely reach mainly the upper 40s and lower 50s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 48° Newark: 50° Philadelphia: 52° Normals: New York City: 30-Year: 40.9°; 15-Year: 41.8° Newark: 30-Year: 41.4°; 15-Year: 42.6° Philadelphia: 30-Year: 42.7°; 15-Year: 43.8° 2021 will conclude on a mild note and 2022 will begin with unseasonable warmth.

It’s an amazing and disconcerting development.

A very warm December is now nearing its conclusion. The remaining days of the month will be generally warmer than normal. New Year's Day could be unseasonably mild. In the South, more near record and record heat prevailed. Preliminary records included: Atlanta: 74° (old record: 72°, 1984) Baton Rouge: 83° (old record: 79°, 1973, 1974, and 1984) Birmingham: 77° (old record: 75°, 1984) Charleston, SC: 80° (old record: 79°, 1984 and 2015) Galveston: 81° (old record: 75°, 1889) ***14th record-breaking or tying temperature of the month*** Houston: 84° (old record: 81°, 1984) Jackson: 83° (old record: 79°, 1984 and 1990) Meridian, MS: 84° (old record: 79°, 1983) ***Tied December Record*** Mobile: 81° (old record: 78°, 1971 and 1974) New Orleans: 81° (tied record set in 1974) Pensacola: 81° (tied record set in 1974) Wilmington, NC: 80° (tied record set in 1984) In addition, Houston recorded its 16th 80° day of this month. The old December record was 10 days, which was set in 2012. Houston also recorded its 6th consecutive 80° day, which broke the December record of 5 consecutive days. The old record was set during December 3-7, 1998 and tied during December 24-28, 2016. Houston is on track to finish with a monthly mean temperature near 67.8°. That would demolish the longstanding December mark of 64.4° from 1933. It would also be high enough to tie 1909 as the 3rd warmest November on record. January will very likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°). The latest guidance suggests that temperatures could head toward seasonal levels and then below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. Afterward, the cold could try to press farther south into at least the northern Middle Atlantic and Ohio Valley regions. The colder pattern could last for two or perhaps three weeks before it breaks down. Thus, it could begin to break down sometime in the January 15-20 timeframe. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.25°C and the ENSO Region 3.4 anomaly has averaged -0.98°C. La Niña conditions will likely persist through meteorological winter. The SOI was +12.04 today. The preliminary Arctic Oscillation (AO) figure was -1.556 today. On December 27 the MJO was in Phase 7 at an amplitude of 2.565 (RMM). The December 26-adjusted amplitude was 2.183 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 43.6° (4.5° above normal). That would tie 2021 with 2006 as the 4th warmest December on record.

Fun fact from Galveston. With 7 80-degree days this month, 2021 has more such days (7) than the combined December 1874-2020 total (4).

Some flowers are already blooming. Forsythia are in bloom in many areas. Some violets and lilac are also in bloom.

Morning thoughts… It will be cloudy with some periods of light rain today. High temperatures will likely reach mainly the middle and upper 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 45° Newark: 47° Philadelphia: 52° Normals: New York City: 30-Year: 41.1°; 15-Year: 42.0° Newark: 30-Year: 41.6°; 15-Year: 42.7° Philadelphia: 30-Year: 42.9°; 15-Year: 43.9° The remainder of December will see above normal temperatures. New Year’s Day looks unseasonably warm.

A very warm December is now nearing its conclusion. The remaining days of the month will be generally warmer than normal. New Year's Day could be unseasonably mild. Near record to record cold, along with snowfall, has continued to occur in the Pacific Northwest and western Canada. Daily record low temperatures included: Edmonton: -31° (old record: -28°, 1996 Medicine Hat, AB: -35° (old record: -13°, 2017) Slave Lake, AB: -30° (old record: -23°, 2013) In the South, more near record and record heat prevailed. Preliminary records included: Atlanta: 75° (old record: 74°, 1971 and 1984) Birmingham: 76° (tied record from 1984) Corpus Christi, TX: 85° (old record: 84°, 1970) Galveston: 82° (old record: 76°, 2016) ***New December Record*** Wilmington, NC: 79° (old record: 76°, 1874, 1889, 1916, 1971, 2008, and 2015) In addition, Houston recorded its 15th 80° day of this month. The old December record was 10 days, which was set in 2012. Houston also recorded its 5th consecutive 80° day, which tied the December record that was set during December 3-7, 1998 and tied during December 24-28, 2016. Houston is on track to finish with a monthly mean temperature near 67.6°. That would demolish the longstanding December mark of 64.4° from 1933. It would also be high enough to rank as the 4th warmest November on record. January will likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°). The latest guidance suggests that temperatures could head toward seasonal levels and then below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. Afterward, the cold could try to press farther south into at least the northern Middle Atlantic and Ohio Valley regions. The colder pattern could last for two or perhaps three weeks before it breaks down. Thus, it could begin to break down sometime in the January 15-20 timeframe. In the Midwest, Chicago picked up its first measurable snowfall of the season. The previous latest first measurable snowfall was December 20, 2012. Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.25°C and the ENSO Region 3.4 anomaly has averaged -0.98°C. La Niña conditions will likely persist through meteorological winter. The SOI was +25.53 today. The preliminary Arctic Oscillation (AO) figure was -1.893 today. On December 26 the MJO was in Phase 7 at an amplitude of 2.182 (RMM). The December 25-adjusted amplitude was 1.957 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 43.5° (4.4° above normal). That would rank 2021 as the 5th warmest December on record.

Chicago has now picked up its first measurable snowfall of the season. This is the latest such snowfall on record. The progression of the record latest first such snowfall is: 11/25/1884, 12/1/1890, 12/2/1904, 12/5/1909, 12/7/1914, 12/12/1946, 12/16/1965, 12/20/2012, and 12/28/2021.

Morning thoughts… Early sunshine will give way to increasing clouds. Light rain and mixed precipitation could develop during the evening or night. High temperatures will likely reach mainly the upper 40s and lower 50s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 50° Newark: 53° Philadelphia: 53° Normals: New York City: 30-Year: 41.3°; 15-Year: 42.2° Newark: 30-Year: 41.8°; 15-Year: 42.9° Philadelphia: 30-Year: 43.1°; 15-Year: 44.1° The remainder of December will see above normal temperatures. In the Midwest, Chicago could pick up its first measurable snowfall of winter 2021-22 today.

Edson only goes back to 1996.

A very warm December is now nearing its conclusion. Following today's seasonal chill, the remaining days of the month will be generally warmer than normal. Near record to record cold, along with snowfall, has continued to occur in the Pacific Northwest and western Canada. Daily record low temperatures included: Banff, AB: -34° (old record: -18°, 1996) Bellingham, WA: 7° (tied record set in 1968) Edmonton: -27° (old record: -20°, 1996) Edson, AB: -45° (old record: -12°, 2012) Grande Prairie, AB: -48° (old record: -46°, 1984) Jasper, AB: -39° (old record: -34°, 1995) Medicine Hat, AB: -30° (old record: -18°, 2017) Pitcher Creek, AB: -32° (old record: -10°, 2012) Red Deer, AB: -35° (old record: -28°, 1965) Seattle: 17° (old record: -20°, 1968) ***Coldest since November 24, 2010*** Vancouver: 4° (old record: 9°, 1971) ***Coldest since January 29, 1969*** In the South, more near record and record heat prevailed. Records included: Abilene, TX: 78° (old record: 77°, 2005) College Station, TX: 81° (old record: 80°, 1889) Midland, TX: 79° (old record: 75°, 1964, 1970, and 1996) In addition, Houston recorded its 14th 80° day of this month. The old December record was 10 days, which was set in 2012. Houston is on track to finish with a monthly mean temperature near 67.5°. That would demolish the longstanding December mark of 64.4° from 1933. It would also be high enough to rank as the 5th warmest November on record. January will likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°). The latest guidance suggests that temperatures could head toward seasonal levels and then below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. Afterward, the cold could try to press farther south into at least the northern Middle Atlantic and Ohio Valley regions. The colder pattern could last for two or perhaps three weeks before it breaks down. In the Midwest, through 4 pm CST today, Chicago has yet to receive its first measurable snowfall. The old record latest first measurable snowfall was December 20, 2012. Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.25°C and the ENSO Region 3.4 anomaly has averaged -0.98°C. La Niña conditions will likely persist through meteorological winter. The SOI was +27.66 today. The preliminary Arctic Oscillation (AO) figure was -2.033 today. On December 25 the MJO was in Phase 7 at an amplitude of 1.956 (RMM). The December 24-adjusted amplitude was 2.131 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 43.5° (4.4° above normal). That would rank 2021 as the 5th warmest December on record.

It was an extraordinary event.

Historic December warmth in Alaska: https://twitter.com/NWSAlaska/status/1475566727127654400?s=20

Today’s high temperature at Fairbanks is 40. The old record of 38 was set in 1909.