bluewave

But the +EAMT leading to the Jet extension is also related to the MJO propagating eastward. https://usclivar.org/working-groups/mjo/science/mjo-atmospheric-angular-momentum-length-of-day#:~:text=MJO and Torques,Ocean (Madden%2C 1988). MJO and Torques Frictional and mountain torques induced by the MJO circulation anomalies are responsible for the angular momentum exchange between the atmosphere and the solid earth. Positive frictional torques start the upward trend in AAM when convection increases over the central Indian Ocean (Madden, 1988). As convection moves to the west Pacific, positive mountain torques from east Asian and South American topography provide for a continued increase in AAM. AAM reaches a maximum as convection weakens near the dateline. The relative roles of a direct forcing by the convection versus eddy transport processes induced by the convection remain to be determined. Real time monitoring of the zonal and global AAM budget provides a convenient monitoring and diagnostic tool of the MJO.

The Arctic region shifts with the anomalous +3 AO following the SSW will probably take further research. It is also a very warm signal for us while working in concert with the tropical convection pattern. Several years back there were papers showing a possible link between the Indian Ocean convection and +AO. So it will be interesting to see if such a strong +AO following this SSW is in any related to the recent record Indian Ocean forcing. We usually don’t see such strong forcing there at the time of SSWs. Would probably be a great project for a research paper.

It’s a combination of the record SSTs in the WPAC for such a strong El Niño and the El Niño itself. So we get MJO action which when combined with El Niño is very warm. As these MJOs progress eastward they excite the +EAMT leading to the Pacific Jet extensions. So just looking at one specific MJO phase composite probably won’t be adequate. This most recent Jet extension will take a few weeks to play out. Hoping we can see some improvements by mid-February relative to the start.

Even in this new era of warmth extremes, what is showing up to start February is way beyond what we have ever seen during an El Niño February. The highly amplified MJO over the WPAC is flipping the script. This would be extreme for December let alone in February when El Niño’s are supposed to be cold. Ridiculous how far into Canada the above freezing line gets pushed.

These Pacific Jet extensions through the highly amplified MJO and +EAMT will continue to run the table at least into early February. So this pretty much guarantees that we’ll see a record breaking 9 warm to record warm winters in a row since the 15-16 super El Niño.

We’ll consider it a January thaw even through the colder period was short.

We know we can easily get a ton of 90° days with a very high dewpoint summer. Plus we can even get a run of 100° days like we saw in 2022. But the extreme 2010 and 2011 all-time absolute highs around 105 to 108 generally require a significant drought nearby. Droughts have been tough to come by with how wet our climate has become.

Reminds me a bit of the big Arctic outbreak to our west in 2021. But with warmer temperatures for us and less snow.

Mostly due to all the excess heat being absorbed by the oceans providing more heat to be released to the atmosphere during El Niño’s. Following the first spike in 97-98, we had all the record winter warmth in the late 90s and our new warmest summer up to that time in 2005 with the hyperactive hurricane season. The next El Niño in 09-10 added more heat leading to the record warm summers in 2010 and 2011. Record blocking accompanied this pattern for several winters. Also Sandy occurred during this period. Then the ridiculous +13 December 15 with that El Niño followed by 9 warmer to record warm winters in a row. So now the global temperature spike in 2023 was higher than any of the previous El Niño’s. So we wait and see what is in store with this new even higher baseline world temperatures.

My guess is that the background pattern was colder for 15-16 once winter got going in January coming off the 09-10 to 14-15 colder winter period. Plus the Pacific actually cooperated wit the -AO back then through Valentines Day. That 15-16 heat release from the oceans rose the baseline temperatures. Now the heat release from this El Niño is even more record breaking than the last one. So it will be interesting to see what two big temperature jumps within 10 years does.

Didn’t have time for the pieces to line up correctly for a big snow for us since the Pacific flow has been so fast with frequent kickers coming into the West Coast.

It’s easier for areas to our south with lower snowfall averages to get to normal snowfall for a set date. All it takes is one storm.

Most of the time in late January when we have a 1040mb high to our north, it’s a good wintry threat pattern. But this time it’s being countered by an almost equally strong Bermuda high. Just goes to show how many challenges our recent winter patterns have been dealing with.

15-16 may have been an exception. Some spots had nearly 40” of snow from late January into early February. Then the first below zero reading in NYC on Valentines Day since 94. We would always find ways to score KU events from 09-10 to 17-18.

That’s what I was commenting on a few weeks back. We were discussing the window, but I was concerned it would be too short to put together more than a 1-3 or 2-4 type event. 16-17 was a really unique winter which was very warm and we seemed to get short term pattern changes which produced blizzards. But ever since 18-19, we needed more time to put together bigger events. Like we saw in December 2020 with the decent pattern becoming established early on leading to the great event around the 17th.

I wasn’t primarily using it to make the forecast for this cold period. The models actually did a decent job. But someone asked about the pattern and how lags worked out. So it was to explain what input it had to the overall pattern. The edge for MJO forecasting usually further out in time say 10-15 days to a month and beyond. The models generally handle short term transitions day 1-5 and 6-10 pretty well . But there are systemic biases at play longer range that once corrected lead to better long range forecast outcomes.

Phase 2 is a very warm phase for us during an El Niño and the convection was focused there for much of early January so not much in the way of a lag there. But the lag this month was with the cold this week was through 3 enhanced by the multiple wave breaks but only lagged by about 3-7 days. The moderation coming up after the weekend has elements of 4 and beyond. Plus we have the interaction with what has happened with the dramatic reversal closer to the Arctic.

The VP anomaly charts are probably closer to the truth with the strongest convection in region 7 during December which was displaced further west than was typical for a canonical El Niño response. The actual convection was off the charts near Australia with all time record rainfall and dewpoints. The previous records were established during La Ninas. This is why the records were so noteworthy for a strong El Niño. But not surprising given the nearly warmest SSTs there on record for this time of year. So it’s also no surprise that the forcing was more prominent in those regions and weaker through some of the other MJO phases on the transit. This is why the RMM charts don’t always tell the whole story. But there are times that they do also. Even in the met community there have been papers written on the strengths and weaknesses of the various approaches at different times. The convection shifted over to phase 2 in early January creating the big pattern shift from strong ridge near the Upper Midwest in December to deep trough near the four corners states. Very predictable shifts given the change in the location of the primary convective forcing.

That isn’t the case. The MJO didn't go into 8 but weakened after the warm 4-7 phases. Then the convection fired in 2 which lead to the very strong trough out West with continuing warmth into mid-January. Another reason you are missing the understanding of a lagged response at times is the resulting Jet extensions which take time for the pattern to fully manifest. So it’s an unreasonable expectation for the MJO to always behave in an instantaneous manner. But there are times when the other factors align to give a more instantaneous response.

I think the big PAC Jet extension kept the pattern too progressive so the storm went more ENE to our south than NE. Another case of the Pacific pattern leading to less snowfall than usual in recent years.

I think we may be using different terminology to describe the same phenomenon. The more robust MJO and convection than usual for such a strong El Niño from the Maritime Continent to just west of the Dateline interacted with the westward displaced El Niño standing wave enhancing the overall strength of the pattern. The location of the standing wave in the phase 7 region of the WPAC aligned more with the December MJO 7 El Niño composite more than the usual canonical El Niño pattern alone. Notice the ECMWF Seas 5 missed the MJO component of the forecast so the ridge and temperature response was too weak. Paul even made a note of it on twitter along with the met community in Australia with the recent record flooding and high dewpoints.

The typical El Niño standing wave in December is just east of the Dateline. This year it was to the west with the wave effectively becoming established in the MJO 7 region. This lead to the warmest December on record for much of North America. The pattern was more similar to the El Niño phase 7 composite than the standard El Niño one which isn’t as warm. The inability of seasonal models like the Euro see the MJO effect beyond a week or two lead to the significant underestimation of the December temperature anomalies in North America. This was why I began pointing out the risks to the warm side for the December forecasts back in the fall. I finally upped my December forecast to +2.5 to 5.0 around the start of December for NYC when I had positive conformation of my earlier thoughts. Also outlined the +10 or more regions in the upper Midwest to Canada. Most forecasts at this time were still much cooler and didn’t really come around to the warmer risks until later in the month.

The standing was was a result of the El Niño interaction with the record WPAC warm pool as the VP anomalies were located further to the west than is typical for an El Niño.

The global warming link has several components. First warmer temperatures lead to record highs across the year greatly exceeding record lows. This has been evident at numerous stations. Places like BHO have had 50 top 10 warmest months and only 1 coldest since 2010. This very high ratio is also evident across our local area. Next, the rapid warming of the WPAC has lead to the MJO slowing down and amplifying in phases 4-7. This is very important implications on a global scale. December 2015 marked the first time such extreme MJO 4-7 behavior was noted during such a strong El Niño. We saw a repeat during this El Niño leading to record VP anomaly amplitude in 7. During both El Niño’s double digit warm departures were noted in parts of North America. So now these competing marine heatwaves act to modulate the expression of the El Niño’s and La Ninas. We saw a similar extreme MJO interaction during the 21-22 La Niña when double digit warm departures were noted in Texas during that December. So the extra heat observed by the oceans has lead to non linear type changes. Where SST temperature thresholds in those regions have been surpassed leading to these standing waves getting stuck in place. They have lead to easily recognizable model errors which great aided in the early realization that the December temperatures would greatly exceed the original long range model forecasts. There have been numerous papers published on all these topics in addition to the lagged effects of these MJO waves. The tropical marine heatwaves have had an outsized influence on our day to day weather. This research has been more fruitful so far than inquiries of this being a result of Arctic amplification and reduced sea ice.

This MJO interaction with the El Niño is causing repeated jet extensions which lead to continuing warm ups.