donsutherland1

I hope we don't get buried in pollen.

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

The ridging across Europe teleconnects to troughs in the Middle East and Northern Africa during the winter.

Recent paper on the 2018-19 SSW event: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/wea.3643

Israel’s biggest snowfalls usually occur with an AO+.

IMO, the GEFS should not be changed to FV3 as long as the documented issues with the GFS persist. Moreover, serious consideration should be given as to whether the move to FV3 makes sense, along with a thorough review of alternative options. With new supercomputing capability, there's little reason not to give genuine consideration to alternative paths. https://www.noaa.gov/media-release/noaa-kicks-off-2018-with-massive-supercomputer-upgrade Unfortunately, my worry is that the "sunk cost fallacy" will constrain thinking among those who make the ultimate choices. If that happens and the performance gap between U.S. modeling and international modeling widens--and the ECMWF, UKMET, and CMC are continuing to make improvements--there will be a risk of a broad loss of confidence in U.S. modeling. That bad scenario would have adverse consequences of its own. That the GFS was the single global model to report a decline in skill in 2019 is troubling. That the impact of such an adverse development may be discounted in favor of pursuing the path chosen when real issues exist is even more troubling.

This is disappointing. From having read his past tweets, it’s difficult to see any rational basis for the suspension.

On February 6, 2020, NBC News reported: Facebook groups that routinely traffic in anti-vaccination propaganda have become a resource for people seeking out a wide variety of medical information — including about the ongoing flu season. Facebook hosts a vast network of groups that trade in false health information. On “Stop Mandatory Vaccination,” one of the largest known health misinformation groups with more than 178,000 members, people have solicited advice for how to deal with the flu. Members of the group have previously spread conspiracies that outbreaks of preventable diseases are “hoaxes” perpetrated by the government, and use the groups to mass-contact parents whose children have died and suggest without evidence that vaccines may be to blame. https://www.nbcnews.com/tech/social-media/facebook-anti-vaxxers-pushed-mom-not-give-her-son-tamiflu-n1131936 Unfortunately, dubious groups such as those cited in the article are not limited to any particular field. Indeed, one sees a vibrant ecosystem of such actors and groups, all devoted to sowing doubt about anthropogenic climate change or outright denying it despite the overwhelming evidence for it. One useful approach for identifying disinformation related to climate change is to examine any claims that seen novel, dismiss climate change, or with which one is unfamiliar. One should check for peer-reviewed research that supports the claim (recent research is stronger than old research that may have been superseded). If such support is found, the claim is credible. If not, it should be viewed as speculative or, at best, a hypothesis that has yet to be tested.

No worries.

For relevant context, my winter idea was warm, but not warm enough. Snowfall for NYC was shown to be somewhat below normal and below normal in Philadelphia to Washington, DC. The statistical probability of April's having a mean temperature of 48° or below (referenced CFSv2 map), which last occurred in 1975 (47.9°), is now less than 1% on account of the warming that has occurred since then. The coldest April since then was April 2018 (49.5°). The last similarly cold or colder April prior to 1975 was April 1943 (46.9°). So, even before the warming of recent decades, such a monthly temperature was a fairly uncommon event. With shorter wave lengths in April, one can't profile the months using teleconnections or ENSO. However, there has been one powerful clue somewhat prior to the start of exceptionally cold Aprils: the presence of severely cold air relative to normal across much or all of Canada during the second half of March. March 16-31, 1943: March 16-31, 1975: From this far out, not even the best ensemble systems can reliably forecast anomalies at such timeframes. Forecasts for extremes need to be backed by strong evidence precisely because extremes are, by definition, low probability scenarios. In the end, while I am not sure whether April will wind up cooler or warmer than normal at this point in February, the climate record (especially when one considers the observed ongoing warming) strongly argues against the kind of scenario on the CFSv2 map (also at very low skill at this timeframe).

A lot depends on the evolution of ENSO. A hot summer is plausible, but so are other outcomes if El Niño conditions try to redevelop.

From this vantage point, spring is looking to be somewhat milder than normal, but a lot more variable than the winter has been, in my view. Parts of Canada may be cooler than normal, especially central and western Canada. Of course, things could still change. Precipitation could be above normal in the region, especially early in the spring.

To average 5 degrees below the current base mean temperature for April (1981-2010), April would need a monthly mean temperature of 48 degrees. Not even April 1982 achieved such cold despite the record cold early in the month. The last time that happened was 1975. Statistically and historically, the probability of the CFSv2 and JB verifying with such cold in the NYC region is very low.

The climatological probability of April's have a temperature anomaly of 5 degrees or more below normal in the New York City area (including NJ and CT) is low. At this point in time, the drivers of the April pattern cannot reliably be pinned down. It is perilous to assume an extreme outcome, especially from this far out. For a reminder of the risks involved, one need look no farther than the forecasts from multiple outlets concerning a severely cold winter that were held through mid-January by which the fundamental winter pattern (strong AO+/EPO+ and related outcomes) were widely evident. Indeed, recognizing the pattern evolution and to its credit, BAMWX threw out its 1995-96 analog at the end of December and has done exceptionally well since then. That move highlights a separate risk that is often ignored: analogs can anchor one to a bad forecast if one holds onto them too long when there is little evidence that things are evolving toward those analogs.

From Copernicus: Global temperatures were substantially above average in January 2020. The month was: - 0.77°C warmer than the average January from 1981-2010, becoming by a narrow margin the warmest January in this data record; - warmer by 0.03°C than January 2016, which was previously the warmest January; - close to 0.2°C warmer than January 2017, which is now the third warmest January; - exceeded in anomalous warmth only by February and March 2016. European-average temperature anomalies are generally larger and more variable than global anomalies, especially in winter, when they can change by several degrees from one month to the next. The European-average temperature for January 2020 was particularly high. The month was: - 3.1°C warmer than the average January in the period 1981-2010; -warmer than any other January in this data record, by about 0.2ºC in the case of January 2007, the previous warmest January. https://climate.copernicus.eu/surface-air-temperature-january-2020

In the case of winter 2006-07, February 2007 was much colder than normal in the Middle Atlantic and southern New England areas.

There's a big difference between pointing out that the impacts of greenhouse gas forcing are influencing the hemispheric circulation (as noted in a growing body of literature), along with other aspects of internal variability, and making the claim that the ultimate outcome will be the disappearance of the NAO- (no literature that I am aware of supports such a claim, though there is some literature suggesting a somewhat greater frequency of the NAO+ state due, in part, to ocean-cryosphere-atmosphere changes).

I'm not sure what impact the fires had, but will be looking to read papers that may be published on the topic. On the latter point, there is literature that suggests that the MJO is starting to spend increasing time in Phases 4-6 in response to changing oceanic heat content and SSTAs. I suspect that we will see such outcomes grow more frequent as the underlying factors driving that situation are persisting, namely continuing greenhouse gas emission increases.

The impact of greenhouse gas forcing on internal variability is becoming an increasingly researched area. One example from recent research: https://ui.adsabs.harvard.edu/abs/2017AGUFMGC41A1002M/abstract

November 15, 2018: 6.4"

Internal variability is occurring within the context of increased greenhouse gas forcing and its consequences. Almost certainly this interaction is leading to changes in patterns, pattern tendencies, and pattern evolution.

Great find. IMO, those who assume a static climate put themselves at greater risk of error in extended range and subseasonal forecasting where the risk of error is already high. The paper to which you posted a link referencing a longer residence of the MJO in the Maritime Continent phases is but one example. Bamwx deserves a lot of credit for being open to what the evidence is suggesting, even if it means changing forecasting approaches and questioning the premises deployed in making forecasts.

Thanks.

What is the ACATT syndicate?

Afternoon thoughts... 1. New York City's 9th warmest January is now nearing an end. 2. Seasonal snowfall to date will be below to much below normal through the end of January from Washington, DC to New York City. The expected spatial distribution of seasonal snowfall is consistent with winters that typically wind up with below to much below normal snowfall in the Middle Atlantic region. 3. The weekend storm will have little or no wintry impact on the region. Eastern New England could still get grazed, but even there any snowfall amounts would likely be light. 4. Some of the teleconnections forecasts point to the development of another strongly positive AO. Cases during which a strongly positive AO coincides with a generally positive EPO during the February 1-15 outcome typically result in a warmer than normal February in the region and below normal February-March snowfall. 5. Until there is credible and consistent evidence of a more favorable hemispheric pattern for signficant snowfalls, Day 10 mirages of the kind seen on today's 12z ECMWF that cruelly tease snow lovers will likely disappear with the passage of time. Sometimes such mirages will disappear with the next model cycle. Occasionally, there can be storms like the February 3-4, 1995 snowstorm that occur in a generally bad pattern, but those are the exception, not the norm.