donsutherland1

It’s possible that the climate data might be missing some of the events. That might be leading to the low figure for 1898-99.

Fantastic work, Hooralph. When you have time, you might want to check 1898-99. It seems to be off. https://www.weather.gov/media/okx/Climate/CentralPark/monthlyseasonalsnowfall.pdf Have a great New Year.

The EPO is positive and is forecast to soar to strongly positive levels early in the first week of January on the EPS.

I suspect that the frozen precipitation threat is well north of the big cities on January 3. Somewhere between Poughkeepsie and Albany might have a good chance of seeing ice and/or at least some snow. As for the transition, it’s still there on the overnight guidance. Sometimes, the guidance rushes things. At that time, the stratosphere will likely be cooling from what was a significant, but not major warming event. The zonal winds are forecast to reverse at 1 mb and 10 mb, but not 30 mb. The polar vortex will be weakening dramatically.

Morning thoughts... Today will be partly cloudy and mild. Temperatures will likely top out in the upper 40s and lower 50s across most of the region. Likely high temperatures around the region include: New York City (Central Park): 50° Newark: 50° Philadelphia: 50° Tomorrow will be fair and seasonably cold.

The extended range of the EPS currently shows an evolution that could lead to a trough in the East between January 10-15. So, unlike last winter when a stubborn EPO+/AO+ pattern locked in, things could be different this time around.

Since 1950, there were 13 cases where the EPO was +1.000 or above while the AO was -1.500 or below for at least three consecutive days during the January 1-20 period. In 3 cases, the Arctic block extended southward into the Middle Atlantic region (January 1-4, 1955; January 15-17, 1998; and, January 1-3, 2003). Below are the composite 500 mb height anomalies and temperature anomalies for that cluster: Mean temperatures were the following: Boston: 33.0° New York City: 37.7° Philadelphia: 40.5° Washington, DC: 43.9° Only Boston saw accumulating snow during the above cases. Its biggest snowfall was 3.5" during January 15-16, 1998. The dynamical guidance is even warmer than these composite anomalies. The closest match from the above cases is the January 1-4, 1955 period. In sum, the forecast pattern is one that will likely favor above to much above normal temperatures and little or no snowfall through at least the first 10 days of January in much or all of the Middle Atlantic Region and southern New England.

After a cold start, temperatures moderated this afternoon. Temperatures generally peaked in the middle and upper 30s across the region. Meanwhile, on account of the strong storm that impacted the region on December 24 into December 25, more record warmth occurred in parts of Canada. That storm also brought blizzard conditions to parts of Nunavut today while eastern portions of that Province experienced unseasonable warmth. Daily record high temperatures included: Badger, NL: 51° (old record: 42°, 2001) Churchill Falls, NL: 36° (old record: 22°, 2011) Corner Brook, NL: 52° (old record: 41°, 2010) Hopedale, NL: 42° (old record: 36°, 1976) Pangnirtung, NU (66.15°N, 65.71°W): 39° (old record: 26°, 2000) St. John's, NL: 50°/10.0°C (old record: 50°F/9.8°C, 1977) Tomorrow will be partly sunny and noticeably milder before cooler air returns to the region. The likely continuation of Arctic blocking through at least the first 10 days of January would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. There is growing ensemble support for the latter outcome. The probability that the block will be anchored near Newfoundland and Labrador in the extended range can inhibit opportunities for snowfall. This can especially be the case should the block attempt to link up to the western Atlantic ridge. In coming days, it will become clearer whether the recent and still ongoing shift in the ensemble guidance toward that outcome will become the most likely scenario for the first half of January. Under this scenario, the first 10 days of January could be much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.57°C and the ENSO Region 3.4 anomaly has averaged -1.17°C. La Niña conditions will likely prevail at least through the winter. The SOI was +15.15 today. Today, the preliminary Arctic Oscillation (AO) figure was -1.954. On December 26 the MJO was in Phase 2 at an amplitude of 0.165 (RMM). The December 25-adjusted amplitude was 0.194. Based on the latest guidance, a significant stratospheric warming event near or just after the start of January is likely. The highest levels of the stratosphere will warm during the closing days of December. The warming will begin to descend during the opening week of January. In addition, the mean zonal winds at 1 mb and 10 mb will likely reverse while the mean zonal wind at 30 mb will likely slacken considerably. There is the proverbial fly in the ointment. It appears that this warming event could produce a split in the polar vortex. Typically, when the polar vortex splits, Eurasia is favored for cold. Displacement of the polar vortex often favors North America. The recent snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue into the start of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

Under bright sunshine, the temperature rose into the middle 30s by early afternoon. Some pictures from around Manursing Lake in Rye, NY:

It looks like a fairly strong event with the mean zonal winds reversing at 1 mb and 10 mb. It’s still uncertain about 30 mb. We’d have to see how the split occurs to have a better idea of its impact. Most, but not all, such cases favor Eurasia

That was a vortex-splitting event. Those typically favor Eurasia.

No. January 1973 had a SSW event, but winter 1973-74 did not.

Morning thoughts... Today will be mostly sunny and cool. Temperatures will likely top out in the upper 30s across most of the region. Likely high temperatures around the region include: New York City (Central Park): 38° Newark: 39° Philadelphia: 38° Tomorrow will be fair and noticeably milder.

At 10:08 pm, the temperature at Kuujjuaq, Quebec (58.1°N, 68.4°W) was 38° with drizzle. Earlier today, the temperature reached a daily record high of 40°. That broke the previous mark of 34°, which was set in 1961. The normal high and low temperature there for December 26 is 0° and -16° respectively.

Despite bright sunshine, the temperature peaked in the lower 30s across the region. Meanwhile, additional record high temperatures were broken in parts of eastern Canada today. Records included: Amherst, NS: 59° (old record: 46°, 2003) Bathurst, NB: 56° (old record: 39°, 2003) Cap-Chat, QC: 60° (old record: 36°, 2014) ***2nd consecutive 60° day for first time on record in meteorological winter*** Caribou: 55° (old record: 53°, 1964) Caribou, NS: 58° (old record: 48°, 2003) Charlottetown, PE: 56° (old record: 52°, 1964) Chéticamp, NS: 58° (old record: 46°, 2003) Gaspé, QC: 54° (old record: 48°, 1977) Goose Bay, NL: 49° (old record: 46°, 1964) Grand Étang, NS: 53° (old record: 46°, 2005) Halifax: 56° (old record: 52°, 1964) Mary's Harbour, NL: 51° (old record: 37°, 2001) Rivière-du-Loup, QC: 53° (old record: 37°, 2014) Saint John, NB: 56° (old record: 55°, 1964) Sept-Îles, QC: 45° (old record: 42°, 1964) Yarmouth, NS: 59° (old record: 53°, 1964) The likely continuation of Arctic blocking through at least the first 10 days of January would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait. There is growing ensemble support for the latter outcome. The probability that the block will be anchored near Newfoundland and Labrador in the extended range can inhibit opportunities for snowfall. This can especially be the case should the block attempt to link up to the western Atlantic ridge. In coming days, it will become clearer whether the recent and still ongoing shift in the ensemble guidance toward that outcome will become the most likely scenario for the first half of January. Nevertheless, there still exists some possibility for a storm during the January 3-5 period that could produce snow. There has been some support among ensemble members for such event. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.57°C and the ENSO Region 3.4 anomaly has averaged -1.17°C. La Niña conditions will likely prevail at least through the winter. The SOI was +8.93 today. Today, the preliminary Arctic Oscillation (AO) figure was +0.112. On December 25 the MJO was in Phase 8 at an amplitude of 0.192 (RMM). The December 24-adjusted amplitude was 0.150. Based on the latest guidance, the probability of a significant stratospheric warming event near or just after the start of January has continued to increase. The highest levels of the stratosphere will warm during the closing days of December. The warming will begin to descend during the opening week of January. In addition, the mean zonal winds at 1 mb and 10 mb will likely reverse while the mean zonal wind at 30 mb will likely slacken considerably. There is the proverbial fly in the ointment. It appears that this warming event could produce a split in the polar vortex. Typically, when the polar vortex splits, Eurasia is favored for cold. Displacement of the polar vortex often favors North America. The recent snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue into the start of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 96% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

Near sunset today:

Morning thoughts... Today will be mostly sunny and cold. Temperatures will likely top out in the lower 30s across most of the region. Likely high temperatures around the region include: New York City (Central Park): 32° Newark: 33° Philadelphia: 33° Tomorrow will be fair and somewhat milder. Some final high temperatures in eastern Canada yesterday included: Cape-Chat, QC: 63°; Mary’s Harbour, NL: 51°; Quebec City: 51°.

000 NOUS41 KCAR 260353 PNSCAR MEZ001>006-010-011-015>017-029>032-261600- PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE CARIBOU ME 1053 PM EST FRI DEC 25 2020 ...PUBLIC INFORMATION STATEMENT... CHRISTMAS 2020 SETS ALL-TIME CHRISTMAS DAY HIGH TEMPERATURE RECORDS ACROSS NORTHERN AND EASTERN MAINE. IN CARIBOU, THE HIGH OF 57F BROKE THE PREVIOUS RECORD OF 48F, LAST SET IN 2014, AND ALSO IN PRIOR YEARS. WEATHER RECORDS BEGAN IN 1939. THE AVERAGE HIGH ON CHRISTMAS DAY IS 23F. IN HOULTON, THE HIGH OF 58F BROKE THE PREVIOUS RECORD OF 53F, LAST SET IN 2014 AND 2003. WEATHER RECORD BEGAN IN 1948. THE AVERAGE HIGH ON CHRISTMAS DAY IS 26F. IN MILLINOCKET, THE HIGH OF 59F BROKE THE PREVIOUS RECORD OF 53F, SET IN 2015. WEATHER RECORDS BEGAN IN 1903. THE AVERAGE HIGH ON CHRISTMAS DAY IS 28F. IN BANGOR, THE HIGH OF 61F BROKE THE PREVIOUS RECORD OF 54F SET IN 2014 AND AGAIN IN 2015. THE AVERAGE HIGH ON CHRISTMAS DAY IS 31F. $$ CB

The definition is qualitative, not quantitative. Measures such as the NAO and AO can provide related quantitative information. https://glossary.ametsoc.org/wiki/Blocking

It is now past midnight in parts of eastern Canada. Numerous daily record high temperatures have fallen in parts of Newfoundland and Labrador and Nova Scotia. Records have also been toppled in parts of Prince Edward Island and New Brunswick. Locations setting records at or just after midnight include Bathurst, NB; Charlottetown, PE; Halifax; Mary’s Harbour, NL; and Saint John, NB. Record high temperatures are likely to fall once midnight arrives in parts of eastern Quebec.

This evening, the temperature rose to 63° (17.2°C) at Cap Chat, Quebec. That broke the December record high temperature. The previous monthly record was 62° (16.7°C), which was set on December 21, 1957. Additional record high temperatures in parts of Canada this evening courtesy of the storm that impacted the region last night and earlier today: Goose Bay, NL: 47° (8.5° C) Mary’s Harbour, NL: 50° (9.9° C) Sept-Îles, QC: 44° (6.4° C)

I hope your family and you had a great Christmas.

Colder air around the backside of the storm that brought damaging winds, heavy rain, and mild temperatures has now overspread the region. Tomorrow will be fair but unseasonably cold. As a strong storm pushed northward, unseasonably warm air covered parts of the Northeast and eastern Canada. Record high temperatures included: Bangor: 61° (old record: 54°, 2014 and 2015) ***Highest Temperature for 2nd Half of December*** Burlington: 65° (old record: 62°, 1964) Cap Chat, QC: 61° (old record: 44°, 2015) Caribou: 57° (old record: 54°, 2003 and 2014) ***Highest Temperature for 2nd Half of December*** Charlottetown, PE: 56° (old record: 54°, 1996) Fredericton, NB: 63° (old record: 54°, 2003) ***Highest Temperature for 2nd Half of December*** Gaspé, QC: 54° (old record: 51°, 2003) Goose Bay, NL: 46° (old record: 45°, 1964) Halifax: 56° (tied record set in 1996) Montreal: 56° (old record: 53°, 1964) Poughkeepsie: 65° (old record: 63°, 1964) Quebec City: 48° (old record: 43°, 2015) Rivière-du-Loup, QC: 55° (old record: 42°, 2015) Saint John, NB: 59° (old record: 55°, 2003) Yarmouth, NS: 58° (old record: 55°, 2003) In parts of eastern Canada, record temperatures remain likely into Sunday. Meanwhile, unseasonably cold air will push into Florida. Record low temperatures are possible in some parts of the state, especially along the Gulf Coast and southern portions of the Florida Peninsula tomorrow morning. The likely continuation of Arctic blocking through at least the first 10 days of January will provide a higher than climatological probability for above normal snowfall with the focus on the January 1-10 period. There is modest clustering of support among the EPS ensemble members for January 3-5. The AO- is particularly important for moderate or significant snowfalls in the New York City and Philadelphia areas. For the December 15-January 15, 1950-2020 period, the following percentages of select snowstorms have occurred when the AO was negative: New York City: 4" or more: 66% 6" or more: 80% 10" or more: 86% Philadelphia: 4" or more: 81% 6" or more: 85% 10" or more: 100% Further, an AO-/PNA+ pattern is especially favorable for moderate or significant snowstorms during the first half of January. For the January 1-15, 1950-2020 period, daily snowfall reached or exceeded 4" on 1.7% of days in New York City and 1.2% of days in Philadelphia. During AO-/PNA+ patterns, those respective frequencies were 2.3% and 1.7%. In short, moderate or significant snowfalls were 37% more common in New York City and 42% more common in Philadelphia during AO-/PNA+ patterns. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.57°C and the ENSO Region 3.4 anomaly has averaged -1.17°C. La Niña conditions will likely prevail at least through the winter. The SOI was +4.88 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.040. On December 24 the MJO was in Phase 7 at an amplitude of 0.149 (RMM). The December 23-adjusted amplitude was 0.368. Based on the latest guidance, the probability of a significant stratospheric warming event near or just after the start of January has continued to increase. The highest levels of the stratosphere will warm during the closing days of December. The warming will begin to descend during the opening week of January. In addition, the mean zonal wind at 1 mb will likely reverse while the mean zonal winds at 10 mb and 30 mb slacken considerably. There is a proverbial fly in the ointment. It appears that this warming event could produce a split in the polar vortex. Typically, when the polar vortex splits, Eurasia is favored for cold. Displacement of the polar vortex often favors North America. The recent snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue into the start of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 95% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

After the storm:

At Caribou, the high temperature through 1 pm was 55° degrees. That broke the daily record of 48° set in 2003 and tied in 2014. It was also the warmest temperature on record for the second half of December. The previous record was 54°, which was set on December 21, 1973 and tied on December 18, 2000.