donsutherland1

A quick note on teleconnections and Washington, DC's 6" or greater January snowstorms (1950-2019): AO-/PNA+: 67% AO+/PNA-: 0% (biggest: 3.9") AO-: 80% PNA+: 87% NAO-: 67% n=12 If one broadens the pool to include 4" or greater snowstorms (n=22), the numbers change very little for all but the NAO: AO-/PNA+: 64% AO+/PNA-: 0% AO-: 77% PNA+: 86% NAO-: 55% Note: All of the 10" or greater snowstorms occurred with an AO-/PNA+

There may be reason for concern. Some recent scientific literature: https://www.nature.com/articles/s41586-019-1764-4

It's due to two major assumptions: 1. The MJO's progression away from the Maritime Continent and through Phase 6 into Phase 7 2. A weakening of the strong polar vortex. There are a number of cases where a super strong polar vortex in early January weakened with sustained blocking occurring in late January and/or February None of this is cast in stone, but there's enough reason to refrain from canceling winter (even if Ji has already done so).

The weakening IOD should reduce interference with the MJO. That should allow it to progress in more typical fashion. The forecast shift to the Maritime Continent (Phases 4-5) is real and the ridging forecast beyond 240 hours is increasingly likely to verify. Absent the MJO, that's still what one would expect given the forecast state of the teleconnections. And if things aren't miserable enough, there's the risk that the EPS weeklies could deliver another serving of misery a little later today. However, this does not mean that it is time to cancel winter. If things work out, the potential for a pattern change for colder and snowier weather could increase during late January. February might offer the best chance for meaningful snowfall in the Middle Atlantic region. We'll see, as a lot of variables are involved, but things should eventually get better all other things being considered.

The AO is particularly important for the Middle Atlantic region and the NAO also carries weight. New England does much better thanks to its higher latitude and has had significant snowstorms even when the AO was in excess of +2.000 in January. The following from my nearly daily discussion in the NYC forum holds true for the MD-DCA-VA areas: Based on the forecast strongly positive AO to start January, the probability of a significant (6" or greater snowstorm) for the major cities of the Middle Atlantic region during the first week of January is low. Since 1950, the biggest snowfall for that region when the AO was +2.000 or above during the January 1-15 period occurred during January 14-15, 1954 when Philadelphia received 3.0" snow and New York City picked up 2.0". Boston has had numerous 6" or greater snowstorms during such cases, including one 10" or greater snowstorm. Therefore, the risk of significant snow would likely be greatest over New England assuming this relationship holds (no significant offsetting variables). Some of the newer AO forecasts keep the AO at +2.000 or above through January 10. If so, that development could adversely impact Mid-Atlantic significant snowfall prospects beyond the first week of January.

That was merely an observation. The main point is that one should not use 1978 as an analogy for the forecast Phases 4-5 MJO in the extended range.

During theJanuary storm, the MJO was moving from Phase 3 into Phase 4 at a super high amplitude. During the February blizzard, it was in Phase 7 and headed for Phase 8 with an exceptional AO block.

MJO forecast update: The GEFS now shows the MJO moving into the Maritime Continent phases at high amplitude. It was the last hold-out. The main caveat is that such MJO forecasts at the timescale involved are still low-skill forecasts. It remains to be seen whether the EPS weeklies will deliver a fresh dose of misery later in the day.

As of 8:30 pm, Allentown had picked up 0.10" rain for the day. That brought total precipitation for 2019 to 60.00". As a result, 2019 became the second consecutive year during which Allentown had picked up 60.00" or more annual precipitation. Last year's figure was 66.96". This is the first time on record that Allentown has had two consecutive years with 60.00" or more precipitation. Records go back to 1901.

A report by Goldman Sachs on climate change: https://www.goldmansachs.com/insights/pages/gs-research/taking-the-heat/report.pdf

The tropical forcing from the MJO can impact the EPO. For example, during the January 1-31, 1981-2019 period, the following relationships existed: MJO in Maritime Continent Phases (4-5) at amplitude of 1.000 or above: EPO+ 61% dates (EPO of +1.000 or above: 28% dates); EPO- 39% dates (EPO of -1.000 or below: 17% dates) MJO in Phase 8 at an amplitude of 1.000 or above: EPO+ 28% dates (EPO of +1.000 or above: 11% dates); EPO- 72% dates (EPO of -1.000 or below: 35% dates) Put another way, when the MJO was in the Maritime Continent Phases, the likelihood of a strongly positive EPO (+1.000 or above) was essentially the same as that for a positive EPO when the MJO was in Phase 8. At the same time, when the MJO was in Phase 8, the likelihood of a strongly negative EPO (-1.000 or below) was similar to the likelihood of a negative EPO during times when the MJO was in the Maritime Continent Phases.

Yes. On the GEFS it does. Still, the one-day change is disconcerting. GEFS 12/28 forecast: GEFS 12/29 forecast:

The 12/29 MJO guidance has moved closer to the Euro. The Canadian and bias-corrected GEFS now takes the MJO into the Maritime Continent phases. The GEFS made a sizable move in that direction from yesterday. The ECMWF has held steady.

One final thought on the potentially major implications of the recent EPS MJO forecast... The forecast shows the MJO emerging into Phases 4 and then moving into Phase 5 at a high and increasing amplitude during the extended range: The composite temperature anomalies for December-February MJO phases are below: For New York City, the below table shows data for the January 10-20, 1981-2019 period for all dates and for dates when the MJO was in Phases 4 or 5 at an amplitude ranging from 1.000 to 2.000: One important caveat: At the current timescale, MJO forecasts have relatively low verification. Therefore, such a scenario is not cast in stone. Greater clarity should develop over the coming week.

A quick note on the 18z GFS: The model showed the EPO diving to historic levels toward or below -5.000 in the extended range. That was radically different from the 12z run and the 18z GEFS. It is an outlier with that teleconnection. Hence, its extended range depiction might be a low probability outcome.

Quick follow up on the discussion concerning possible East Coast ridging for the January 10-17 period: 1. The 12z EPS builds the ridging, especially from 300 hours to 360 hours 2. The 12z GEFS shows some ridging now, but it could be transient there. Still that's a pretty big change from 24-48 hours ago. 3. The ECMWF still shows the MJO briefing passing through Phases 7-8 and then entering the dreaded Maritime Continent at high and increasing amplitude in the extended range. So, at least for now, my concerns about the specified period above persist, namely that transient cold could give way to a period of milder conditions. Afterward, much will depend on the MJO's progression and the evolution of the teleconnections.

Noting that there will be a mild start should not be seen as giving up. Big flips have occurred in the past i.e., 2005 and 2007. Hopefully, we will see something similar this time around.

Thanks Ottawa Blizzard. I hope all is well with you. I'm not sure what The Weather Network and Weatherbell saw or on which they based their forecasts. The composite temperature anomalies for neutral-warm/borderline weak El Nino cases didn't favor widespread cold in Canada (northern Canada was favored), especially in Ontario. The C3S multi-system guidance also favored warmth across a large part of Canada. Toronto will likely wind up having a warmer than normal winter. Unfortunately, snowfall appears to be in line for a below normal season.

An important paper concerning the impact of the stratospheric polar vortex... Abstract: The impact of the Arctic stratospheric polar vortex on persistent weather regimes over North America is so far underexplored. Here we show the relationship between four wintertime North American weather regimes and the stratospheric vortex strength using reanalysis data. We find that the strength of the vortex significantly affects the behavior of the regimes. While a regime associated with Greenland blocking is strongly favored following weak vortex events, it is not the primary regime associated with a widespread, elevated risk of extreme cold in North America. Instead, we find that the regime most strongly associated with widespread extremely cold weather does not show a strong dependency on the strength of the lower stratospheric zonal mean zonal winds. We also suggest that stratospheric vortex morphology may be particularly important for cold air outbreaks during this regime. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085592

The first half of January =/= the remainder of winter. As noted in the past, one has to be wary of Social Media. Exaggeration is commonplace (big snowstorms, extreme cold, stratospheric warming events, and now claims about an impending demise of winter) on Social Media. Even as January appears likely to be warmer than normal on average, that does not mean that sustained cold with opportunities for snowfall can't develop later in the month or that February could not feature above normal snowfall.

With regard to the Week 3 (January 10-17) Ridging in the East: There is a wide range of thought concerning this potential ridging (the "missing piece" I alluded to yesterday on a GEFS map). Unfortunately, a day later, the EPS, GEFS, and Canadian ensembles have all "found" this piece. That raises the question as to whether it is a realistic model depiction in a timeframe where skill scores are low. I believe it is. This does not, of course, mean that I expect it to persist through much or all of the remainder of January. It's far too soon to make such a call. I do believe it is a crucial development that will likely lead to a warmer than normal month as a whole in much or all of the East (I'm currently thinking somewhere in the vicinity of 1.5° above normal but haven't finalized the number). My reasoning concerning the development of the ridging is as follows: 1. The latest EPS (and GEFS) forecasts the MJO to move into Phase 5 toward January 10 (the start of the period in question). Model guidance has grown firmer on this idea in recent days, though such forecasts are still in a time range with low skill (and a wider turn that takes it through an alternative path that includes Phases 7-8-1 rather than 4-5 can't be ruled out). The fading IOD+ may also still be constructively interfering with the MJO. Rossby wave activity may also have an impact. The 200 mb height anomaly (DJF with no lag) for Phase 5 produces a map that is quite similar to the forecast 500 mb anoamlies shown on the latest ensemble guidance (including the 6z GEFS) in the extended range: Any time one of the composite maps fits modeled output suggests one should give at least some consideration to that output. 2. The 12/27 0z EPS and 12/27 6z GEFS show the development of ridging in the East in the extended range (present from hour 336 and afterward on the EPS and from hour 354 and afterward on the GEFS). The CFSv2 week 3 forecast also shows such ridging. 3. The pattern fits the January 500 mb pattern with a monthly AO of +1.000 or above and an EPO > 0 (1950-2019). 4. The ensemble forecasts call for a strong polar vortex to be present through at least January 10. 5. No significant stratospheric warming events are likely through at least the middle of the first week of January according to the EPS. Overall, there is a body of evidence that argues for ridging to develop in the East around January 10 +/- a few days. Whether such ridging persists will depend on the progression of the MJO (will it spend appreciable time in the Maritime Continent before progressing through Phases 6 and 7 and 8 should the EPS forecast verify?) and the state of the teleconnections (persistence of AO+/EPO+). Some of the new guidance shows the EPO falling to neutral late in the first week of January or just afterward, so that's a positive development that will need to be watched. At the same time, some of the recent guidance shows the development of a PNA- in the extended range, a development that would also favor ridging in the East. As always, it should be noted that such forecasts have low skill and may change considerably over a week or two. Moreover, I could be wrong. The main point was that there is a body of evidence to suggest that the forecast development of ridging is plausible. The picture should become clearer over the next week.

One shouldn't be surprised that Heller, who has no scientific background, would imply that the winter freeze suggests a healthy Arctic sea ice situation. The difference between the 12/23 extent and minimum extent is largely the result of a very low minimum figure. According to Heller's logic, 2012 would have been seen as a fantastic year, as sea ice extent increased by nearly 8.7 million square kilometers by December 23. Of course, 2012 saw a record low minimum extent figure of just under 3.2 million square kilometers. In fact, the 12/1-23 average of 11.144 million square kilometers is the 3rd lowest on record and is nearly 3% below the 2000-19 average. This is not a healthy Arctic sea ice situation. If multi-year "old" ice were increasing, that would be newsworthy. The annual refreeze in 2019 is not.

Thanks for the kind words and Holiday wishes. I hope your family and you have a great Holiday season.

There's a fallacy that complexity of making weather forecasts at extended ranges means that climate forecasts years out are essentially not possible to make. A closer look is in order for purposes of a quick sketch. Take for example, New York City (Central Park). Let's say one is seeking to forecast the high temperature on January 1, 2020. The highest maximum temperature on record is 62°, which occurred in 1966. The lowest maximum temperature on record is 10° from 1918. The 0z GFS forecast a high of 36°. The historic range is 1.4 times the forecast high. Finally, let's say one is seeking to forecast the 2020 annual mean temperature. The warmest such reading was 57.4° in 2012. The coldest such reading was 49.5° in 1875 and 1888. Since 2000, the mean has averaged 55.7°. If one uses that estimate, the range of error is just under 0.15 times the estimate. That latter situation is the type of situation one is dealing with when it comes to making climate projections. Thus, the fallacy of synoptic complexity's precluding climate forecasts does not apply. When it comes to climate (and climate change) there are widely-established drivers of climate: solar and greenhouse gases are among the most important. Therefore, if one gets the forcings right, one should get a reasonable projection of the climate. Well, that's exactly what the research shows. Climate models have proved skillful. Retrospectively comparing future model projections to observations provides a robust and independent test of model skill. Here we analyse the performance of climate models published between 1970 and 2007 in projecting future global mean surface temperature (GMST) changes. Models are compared to observations based on both the change in GMST over time and the change in GMST over the change in external forcing. The latter approach accounts for mismatches in model forcings, a potential source of error in model projections independent of the accuracy of model physics. We find that climate models published over the past five decades were skillful in predicting subsequent GMST changes, with most models examined showing warming consistent with observations, particularly when mismatches between model-projected and observationally-estimated forcings were taken into account. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085378 Key takeaway: Climate should not be viewed through a synoptic lens. Finally, the physical properties of carbon dioxide are well-established. There's no serious scientific debate on that matter. Therefore, it should make little difference whether carbon dioxide is released through natural mechanisms or if human activities release carbon dioxide. The molecules should behave in the same fashion, not follow different rules depending on whether they were emitted into the atmosphere via volcanic eruptions or the burning of fossil fuels.

It won't melt immediately and could take centuries to do so. Nevertheless, it appears that humanity is committing itself to a course that could lead to that outcome given little or no response to the need to reduce greenhouse gas emissions (projected to have increased another 0.6% this year). The latest Arctic Report Card provides a glimpse of what is currently happening in the Arctic. https://www.arctic.noaa.gov/Portals/7/ArcticReportCard/Documents/ArcticReportCard_full_report2019.pdf