donsutherland1

Bloomberg.com reported that the U.K. will be making a significant investment to upgrade its weather and climate computer resources. https://www.bloomberg.com/amp/news/articles/2020-02-17/u-k-to-spend-1-6-billion-on-world-s-best-climate-supercomputer

As has happened on a regular basis during January and the first half of February, the cold that covered the Northeast during Friday and yesterday was short-lived. Milder air has again overspread the region. Much of the Middle Atlantic region saw high temperatures top out in the lower and middle 40s. A few readings at or above 50° occurred, as well. Another short period of cold is likely later this week. Nevertheless, the second half of February will likely be warmer than normal overall. Cooler air could arrive by the end of February or the beginning of March, but its magnitude and duration are uncertain at present. Winter 2019-2020 is the 7th winter on record that has seen Philadelphia receive less than 2" seasonal snowfall through February 16. Mean total snowfall for the 6 prior cases was 3.8" vs. the historic mean figure of 22.6". In addition, 100% of such winters wound up with less than 10" seasonal snowfall vs. 16% of winters in the historic record. The snowiest case from those prior winters was 1931-32 with 8.0" seasonal snowfall. Consistent with the pattern and supported by most of the guidance, no significant snowfalls (6" or more) are likely in the major Middle Atlantic cities through at least the first 24 days of February. There is a greater but still fairly low probability for Boston to see such a snowstorm. Earlier today, in part due to the powerful north Atlantic storm that has contributed to the very strongly positive Arctic Oscillation (AO), widespread record warmth prevailed in Europe. Daily records included: Amsterdam: 59°; Antwerp: 63°; Cherbourg, France: 57°; Deelen, Netherlands: 63°; Dusseldorf: 64°; Eindhoven, Netherlands: 64°; Gilze-Rijen, Netherlands: 63°; Hamburg: 63° (tied monthly record); Kleine Brogel, Belgium: 64°; Koksijde, Belgium: 59°; Luxembourg: 61°; Paris: 64°; Rotterdam: 59°; Satenas, Sweden: 50°; Strasbourg, France: 68°; Volkel, Netherlands: 64°; Wiesbaden, Germany: 61°; and, Wunstorf, Germany: 64° (tied monthly record). The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.2°C for the week centered around February 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.22°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. The remainder of winter 2019-2020 will likely feature neutral-warm to weak El Niño conditions. The SOI was -18.20 today. Today, the preliminary Arctic Oscillation (AO) figure was +4.169. That easily exceed the previous daily record of +3.114 from 1959. No significant stratospheric warming is likely through February 24, but the upper stratosphere above 3 mb will likely be warm. Wave 2 activity will remain relatively suppressed. Overall, most of the stratosphere is forecast to remain cold on the EPS into the third week of February. On February 15, the MJO was in Phase 5 at an amplitude of 1.777 (RMM). The February 14-adjusted amplitude was 1.500. Based on sensitivity analysis applied to the latest guidance, there is an implied 94% probability that New York City will have a warmer than normal February and an implied 61% probability that February 2020 will be among the 10 warmest such months on record. The mean monthly temperature will likely finish near 39.5°. Finally, a sizable majority (>80%) of years during which the AO has been, on average, strongly positive during the first 15 days of February were followed by a warmer than normal March. The preliminary February 1-15 AO average was +2.758. Only 1989 (+3.336) and 1990 (+2.948) had higher AO averages during this period. Recent rapid warming in ENSO Region 1+2 has also typically preceded a warmer than normal March and spring in the Middle Atlantic region. The most recent C3S multi-system blend favors a somewhat warmer than normal spring in the region.

With snowfall prospects likely remaining bleak through much of the second half of February, at look at March concerning the Arctic Oscillation and PNA is useful. During March, the wave lengths are continuing to shorten, so the diversity of 500 mb patterns with (and also without) snow tends to increase. Below is data for March 1981-2019 for Philadelphia: AO-/PNA-: Mean Temperature: 43.0 degrees % Days with Measurable Snow: 4.3% % Days with 1" or More Snow: 2.2% AO-/PNA+: Mean Temperature: 42.1 degrees % Days with Measurable Snow: 7.0% % Days with 1" or More Snow: 2.8% AO+/PNA-: Mean Temperature: 43.3 degrees % Days with Measurable Snow: 10.0% % Days with 1" or More Snow: 5.0% AO+/PNA+: Mean Temperature: 45.1 degrees % Days with Measurable Snow: 3.6% % Days with 1" or More Snow: 1.6% March 1981-2019 Period: Mean Temperature: 43.4 degrees % Days with Measurable Snow: 6.3% % Days with 1" or More Snow: 2.9% Biggest Snowstorm (March 1950-2019): AO-/PNA-: 11.4", March 1958 AO-/PNA+: 8.8", March 1981 AO+/PNA-: 12.0", March 1993 AO+/PNA+: 6.0", March 2017 (only 4" or greater snowstorm with this combination) Of course, more is involved than the state of the teleconnections. But the teleconnections can provide some starting insight.

This morning was the coldest morning of winter 2019-2020. Both New York City and Philadelphia had minimum temperatures of 14°. Readings outside those cities were even colder. Low temperatures outside New York City and Philadelphia included: Allentown: 10°; Danbury: 6°; Poughkeepsie: 6°; Scranton: 5°; and, White Plains: 9°. Binghamton had a low temperature of -2°. In addition, New York City's high temperature of 30° was that city's lowest high temperature since December 19, 2019 when the high temperature was just 25°. Philadelphia recorded only its second high temperature of 32° or below this winter. Today's 32° high temperature was Philadelphia's lowest maximum temperature since December 19 when the high temperature was 29°. However, as has been the case since the second half of December, the cold will now quickly depart. Moreover, other than transient cold shots, one of which could during the second half of next week, the second half of February will likely be warmer than normal overall. Consistent with the pattern and supported by most of the guidance, no significant snowfalls (6" or more) are likely in the major Middle Atlantic cities through at least the first three weeks of February. There is a greater but still fairly low probability for Boston to see such a snowstorm. The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.2°C for the week centered around February 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.22°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. The remainder of winter 2019-2020 will likely feature neutral-warm to weak El Niño conditions. The SOI was -21.95 today. The last time the SOI fell to -20.00 or below was December 26, 2019 when the SOI was -28.39. Today, the preliminary Arctic Oscillation (AO) figure was +2.700. No significant stratospheric warming is likely through February 23, but the upper stratosphere above 3 mb will likely be warm. Wave 2 activity will remain relatively suppressed. Overall, most of the stratosphere is forecast to remain cold on the EPS into the third week of February. On February 14, the MJO was in Phase 6 at an amplitude of 1.502 (RMM). The February 13-adjusted amplitude was 1.235. Based on sensitivity analysis applied to the latest guidance, there is an implied 90% probability that New York City will have a warmer than normal February and an implied 55% probability that February 2020 will be among the 10 warmest such months on record. Finally, a sizable majority (>80%) of years during which the AO has been, on average, strongly positive during the first 15 days of February were followed by a warmer than normal March. The preliminary February 1-15 AO average was +2.758. Only 1989 (+3.336) and 1990 (+2.948) had higher AO averages during this period. Recent rapid warming in ENSO Region 1+2 has also typically preceded a warmer than normal March and spring in the Middle Atlantic region.

Two photos from this afternoon (temperature 29°). Ice left over from the receding tide and bubbles in a frozen pool of water.

Not if the MVP is negative. Hopefully, it won’t be negative.

This morning, the temperature fell to 14° in Philadelphia. That was the coldest temperature this winter and the coldest since February 2, 2019 when the temperature fell to 11°. So far, Philadelphia has had no days in January or February during which the high temperature reached no higher than 32°. The only time January and February saw no such days was in 1932. December 1931 also had no such days. However, March 1932 had 4 days during which the high temperature reached no higher than 32°.

I was referring to today. That was yesterday’s 12z run. Both today’s 0z and 12z runs dropped the storm.

While the GFS is largely on its own with this idea, it should be noted that during winter 1972-73, Columbia, SC picked up 16.0" snow on February 9-10. That winter, just 2.8" snow fell in New York City and only a trace was recorded in Philadelphia.

On GISS, January 2020 was the warmest January on record globally. The temperature anomaly was +1.18°C, which was narrowly above the previous record of +1.17°C from 2016.

Temperatures were falling through the 20s this evening in the northern Middle Atlantic region. The minimum temperature tomorrow morning could fall into the teens in New York City and Philadelphia. Readings in the lower teens and perhaps single digits are likely outside both cities. But then winter's latest effort to take hold will fail again. Warmer air will quickly return. It is likely that the second half of February will be warmer than normal overall. During that time, cold shots will likely be of a short duration. Consistent with the pattern and supported by most of the guidance, no significant snowfalls (6" or more) are likely in the major Middle Atlantic cities through at least the first three weeks of February. There is a greater but still fairly low probability for Boston to see such a snowstorm. Winter 2019-2020 became the 19th winter on record that saw New York City receive less than 6" seasonal snowfall through February 14. Mean total snowfall for the 18 prior cases was 12.5" vs. the historic mean figure of 28.8". In addition, 39% of such winters wound up with less than 10" seasonal snowfall vs. 6% of winters in the historic record. 89% of such winters wound up with less than 20" seasonal snowfall vs. 31% of winters in the historic record. Just 11% of such winters wound up with 30" or more seasonal snowfall vs. 41% of winters in the historic record. The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.2°C for the week centered around February 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.22°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. The remainder of winter 2019-2020 will likely feature neutral-warm to weak El Niño conditions. The SOI was -17.05 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.686. No significant stratospheric warming is likely through February 22, but the upper stratosphere above 3 mb will likely be warm. Wave 2 activity will remain relatively suppressed. Overall, most of the stratosphere is forecast to remain cold on the EPS into the third week of February. On February 13, the MJO was in Phase 6 at an amplitude of 1.234 (RMM). The February 12-adjusted amplitude was 1.122. Based on sensitivity analysis applied to the latest guidance, there is an implied 89% probability that New York City will have a warmer than normal February and an implied 55% probability that February 2020 will be among the 10 warmest such months on record. Finally, a sizable majority (>80%) of years during which the AO has been, on average, strongly positive during the first 15 days of February were followed by a warmer than normal March. The preliminary February 1-12 AO average is +2.926. Recent rapid warming in ENSO Region 1+2 has also typically preceded a warmer than normal March and spring in the Middle Atlantic region.

A very warm winter has had a higher frequency of warm summers in Philadelphia. Based on data from winters 1873-74 to the 2018-19, the historic summer average temperature was 74.9°. Warm summers were as follows: Above the historic mean: 45% 1° or more above the historic mean: 25% 2° or more above the historic mean: 12% In the 19 cases where the December-February mean temperature was 38.0° or above (2019-20 was averaging 39.6° through 2/13), the mean summer temperature was 76.1°. Warm summers were as follows: Above the historic mean: 79% (1.8X the historic frequency) 1° or more above the historic mean: 53% (2.1X the historic frequency) 2° or more above the historic mean: 32% (2.6X the historic mean and more frequent than the historic figure for 1° or more above the historic mean) All said, if the above data is representative, summer 2020 will likely be warmer and possibly much warmer than normal. The evolution of ENSO will have an important impact.

Winter 2019-2020 is just the 7th winter on record that has seen Philadelphia receive less than 2" seasonal snowfall through February 14. Mean total snowfall for the 6 prior cases was 3.8" vs. the historic mean figure of 22.6". In addition, 100% of such winters wound up with less than 10" seasonal snowfall vs. 16% of winters in the historic record. The snowiest case from those prior winters was 1931-32 with 8.0" seasonal snowfall. Below is a chart that illustrates mean and +/- 3 sigma cumulative snowfall amounts based on the 0.3" that has fallen to date for those six cases. The 3 sigma upper limit based on those 6 cases is 11.3". Statistically, there would be a 1-in-741 chance that this value would be reached or exceeded. *-The - sigma value has been constrained to that it cannot fall below the 0.3" seasonal snowfall to date. That value would imply no measurable snowfall for the remainder of winter 2019-2020.

An insightful video (h/t Mark Boslough):

It should be noted that since winter 1869-70, there is only 1 case where seasonal snowfall through February was less than 10" and March had an 8" or greater snowfall in New York City: 1956. Seasonal snowfall through February 1956 was 8.2". The February 1956 AO average was -2.029. The second lowest figure was 10.8" in 1981 (February AO: -0.331).

The temperature fell to 16 degrees on December 19.

The President's Day snowstorm was the highlight of a remarkably cold winter. Almost the entire CONUS was colder to much colder than normal.

At 7 pm EST, the temperature was 10° in Chicago, 19° in Detroit, 33° in Pittsburgh, 43° in New York City,and 47° in Philadelphia. The cold that has now moved into the Great Lakes region will be pushing into the region overnight. As a result, readings will be much below normal tomorrow and on Saturday. The lowest temperatures on Saturday morning could fall into the teens in New York City and Philadelphia. Readings in the lower teens and perhaps single digits are likely outside both cities. But then winter's latest effort to take hold will fail again. Warmer air will quickly return. It is likely that the second half of February will be warmer than normal overall. During that time, cold shots will likely be of a short duration. Consistent with the pattern and supported by most of the guidance, no significant snowfalls (6" or more) are likely in the major Middle Atlantic cities through at least the first three weeks of February. There is a greater but still fairly low probability for Boston to see such a snowstorm. On this date in 2014, Philadelphia received a daily record 10.4" snowfall. This winter, the city is mired in a deepening snow drought. Winter 2019-2020 is just the 7th winter on record that saw Philadelphia receive less than 2" seasonal snowfall through February 13. Mean total snowfall for the 6 prior cases was 3.8" vs. the historic mean figure of 22.6". In addition, 100% of such winters wound up with less than 10" seasonal snowfall vs. 16% of winters in the historic record. The snowiest case from those prior winters was 1931-32 with 8.0" seasonal snowfall. The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.2°C for the week centered around February 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.22°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. The remainder of winter 2019-2020 will likely feature neutral-warm to weak El Niño conditions. The SOI was -12.49 today. Today, the preliminary Arctic Oscillation (AO) figure was +1.860. No significant stratospheric warming is likely through February 21, but the upper stratosphere above 3 mb will likely be warm. Wave 2 activity will remain relatively suppressed. Overall, most of the stratosphere is forecast to remain cold on the EPS into the third week of February. On February 12, the MJO was in Phase 6 at an amplitude of 1.121 (RMM). The February 11-adjusted amplitude was 1.211. Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal February and an implied 50% probability that February 2020 will be among the 10 warmest such months on record. Finally, a sizable majority (>80%) of years during which the AO has been, on average, strongly positive during the first 15 days of February were followed by a warmer than normal March. The preliminary February 1-12 AO average is +2.926. Recent rapid warming in ENSO Region 1+2 has also typically preceded a warmer than normal March and spring in the Middle Atlantic region.

Philadelphia had measurable snowfall in January 1979 (first was 1/5 when 1.2" fell). The February days with measurable snowfall were as follows: 2/7 7.6" 2/12 4.8" 2/14 0.4" 2/15 0.3" 2/16 0.2" 2/18 0.4" 2/19 13.9"

The NOAA also reported that January 2020 was the warmest January on record globally. https://www.ncdc.noaa.gov/sotc/global/202001

On February 9, 2020, a record temperature of 20.75 degrees C (69.35 degrees F) was recorded on Antarctica's Seymour Island. https://www.theguardian.com/world/2020/feb/13/antarctic-temperature-rises-above-20c-first-time-record

Winter 2019-2020 became the 7th winter on record that saw Philadelphia receive less than 2" seasonal snowfall through February 12. Mean total snowfall for the 6 prior cases was 3.8" vs. the historic mean figure of 22.6". In addition, 100% of such winters wound up with less than 10" seasonal snowfall vs. 16% of winters in the historic record. The snowiest case from those prior winters was 1931-32 with 8.0" seasonal snowfall. Winter 2019-2020 is also only the 3rd winter on record to receive less than 1" seasonal snowfall through February 12. The others were 1972-73 (0.0") and 1997-98 (0.7").

Tomorrow will very likely see temperatures top out in the 50s in much of the Middle Atlantic region. However, a brief shot of modified Arctic air will move into the region for Friday and Saturday. The lowest temperatures could fall into the teens in New York City and lower teens and perhaps single digits outside the City. Afterward, warmer air will quickly return. It is likely that the February 15-21 period will be warmer than normal overall. Any cold shots would likely be of a short duration. The general above normal temperature regime could persist afterward. Consistent with the pattern and supported by most of the guidance, no significant snowfalls (6" or more) are likely in the major Middle Atlantic cities through at least the first three weeks of February. There is a greater but still fairly low probability for Boston to see such a snowstorm. The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.2°C for the week centered around February 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.22°C and the ENSO Region 3.4 anomaly has averaged +0.48°C. The remainder of winter 2019-2020 will likely feature neutral-warm to weak El Niño conditions. The SOI was -9.03 today. Today, the preliminary Arctic Oscillation (AO) figure was +3.286. No significant stratospheric warming is likely through February 20, but the upper stratosphere above 5 mb will likely warm toward mid-February. Wave 2 activity will remain relatively suppressed. Overall, most of the stratosphere is forecast to remain cold on the EPS into the third week of February. On February 11, the MJO was in Phase 5 at an amplitude of 1.204 (RMM). The February 10-adjusted amplitude was 1.540. Based on sensitivity analysis applied to the latest guidance, there is an implied 86% probability that New York City will have a warmer than normal February and an implied 56% probability that February 2020 will be among the 10 warmest such months on record. Finally, a sizable majority (>80%) of years during which the AO has been, on average, strongly positive during the first 15 days of February were followed by a warmer than normal March. The preliminary February 1-12 AO average is +2.926. Recent rapid warming in ENSO Region 1+2 has also typically preceded a warmer than normal March and spring in the Middle Atlantic region.

I hope we don't get buried in pollen.

Good news: Climate scientist Brian Brettschneider's Twitter account has been restored to full functionality.