bluewave

Thank you for the kind words. It’s good to see that we can each use different methods and converge on similar solutions. You do a fantastic job putting together your seasonal outlooks. It’s why this extended format discussion forum is such a valuable resource bringing us all together in the same spot.

Yeah, this is what I have been discussing. The rapid warming of the WPAC tropical SSTs near the near the Maritime Continent has been stalling the MJO in the warmer storm track and background temperature phases. So the MJO progression tends to linger longer in the 4-7 phases and spend less time in phase 8. This is why January 2022 was the last time that the RMM and VP anomaly charts were both solidly in Phase 8. From March 2022 through the winter of 2024-2025 the few MJO 8s per the RMM charts had lingering forcing in phase 5-7 regions. So we didn’t fully realize the MJO 8 pattern which we last had in January 2022. Many times the models try to rush the progression through phase 8 and it gets delayed and or weakened the closer in time we get to the forecast period. This is what is shown when we subtract the last 16 years from the previous 16 years. You can see the stronger forcing closer to phases 6-7 where the warmest SSTs on earth near +30C are found during the winter. This +28C +30C warm pool has been steadily expanding across that region.

During more +PNA intervals like this fall the, the Southeast ridge was focused to the east building into Eastern New England and Canada on our 10 wettest storm days. So these frequent WAR and Southeast ridge patterns are interchangeable. They both have been leading to dominant Great Lakes cutter and hugger storm tracks whether we have had +PNA or -PNA patterns over the last 7 years since 2018-2019. 10 wettest days storm track 500 mb composite this fall around the area with dominant Great Lakes cutter and hugger storm tracks and strong +PNA WAR pattern

The long range EPS keeps underestimating that forcing in the 120E to 150E Maritime Continent regions. New run Old run

Record WPAC warm pool in conjunction with the cold over Siberia continue to create the very strong thermal gradient leading to the faster Pacific Jet and dominant Northern Stream Storm track. The tropical warm pool near the equator and the record subtropical warm pool to the east of Japan and south of the Aleutians both enhance the Southeast ridge. Plus the record Gulf Stream SSTs also contribute. Models tend to underestimate this long range influence as we are seeing with the new forecasts in early December with stronger Southeast ridge than originally forecast. Once this pattern becomes established, it can linger longer than expected as we have often seen heading into December over the last decade. New EPS forecast for December 1-8 Old EPS forecast December 1-8

It’s good that all of us using different methods had a weaker PNA for this December than the record +PNA La Niña mismatch last December following the stronger amplitude MJO 5 over +2.70 in October 2024.

I guess it will be fitting that Thanksgiving is set to follow the same windy pattern we have seen all year. Mild Great Lakes cutter storm track on Wednesday. Then strong W to NW flow on Thursday. The one hope is that the strongest winds of around 40 mph peak after parade time. But you can see this year already has double the number of 40 mph gust days as any previous year at over 60. Most of the gusts since January have occurred behind Great Lakes or hugger storm tracks on W to NW flow. The one lone coastal storm back in October was one of the few days with a NE gust over 40 mph.

The long range EPS generally underestimates the Pacific Jet and the forcing near the Maritime Continent. So both those factors lead to a stronger Southeast ridge. Plus it makes it challenging to get a clean MJO 8 pattern with forcing lingering there.

The more +NAO following the wave reflection in concert with the stronger Maritime Continent forcing will both act to enhance the Southeast ridge as we had into December. Remember, the original forecasts for the first week of December didn’t have any Southeast ridge. Models regularly underestimate the Southeast ridge influence in the long range. Either through the 5 day means or with the storm track which amplifies the Southeast ridge on the days of the storms. New EPS December 1-8 forecast Old EPS December 1-8 EPS forecast

The videos from Svalbard are pretty wild also.

You can already see the model differences between the EPS, GEFS, and GEPS at the end of their respective runs. The GEFS and GEPS hold onto the Western trough and Southeast ridge longer than the EPS. It’s probably due to the GEFS and GEPS showing more Maritime Continent forcing longer than the EPS. One of the EPS biases is dampening the convection too much there week 2 and beyond. This is why I like to use the VP anomaly charts over the RMM charts which can follow the convection to the east. One of the features of recent Decembers is a tendency for the forcing to linger in that region than the models originally anticipate. This lingering convection is why it has been so difficult in recent years to get a clean MJO 8 with no convection in that area like we last had in January 2022. So patience is often required this time of year as the pattern change to colder is usually delayed.

The real cold on Thanksgiving will be closer to Siberia. You have to give those people credit for surviving in such a cold environment. Luckily, their energy bills to heat their units are relatively low compared to what we would be paying if it ever got that cold here.

Late last November into early December the EPS and GEFS were forecasting the +PNA -EPO to extend through the holidays. But they greatly underestimated the Pacific Jet and we got the big jet extension which lead to the record +EPO and warmer pattern later in the month. I was highlighting the warmer risks back in the threads going into early December last year. Then we got the big January suppression pattern with the record snowstorm on the Gulf Coast. There was a kicker coming into Western Canada at the time that contributed to that suppression. The MJO 8 was really brief in phase 8 on the RMMS last January but we had lingering forcing on the VP charts near the Maritime Continent which may have prevented the Pacific Jet from fully relaxing like our last successful MJO 8 in January 2022. Then in early February the extended EPS was trying to forecast a snowy gradient pattern near NYC. I mentioned that the gradient would probably shift to the north. Then we got the record Great Lakes cutter with the -5SD Greenland block which linked with the Southeast ridge and Toronto hot the record snows. Since the models underestimated the Southeast ridge again. This is why I don’t have any confidence when models show big patterns in the week 2 and week 3 time ranges. If a big pattern shows up under 120 hrs, then I will get on board.

Looks like a little warmer than average as we head into the last week of November. Storm track remains through the Great Lakes. So the warm ups will be a bit more impressive than the cool downs which follow. But nothing too extreme in terms of temperatures and storms.

Models really struggle with the December forecast progression of the pattern in late November. That’s why I would like to see everything play out over the next few weeks before getting too excited this early. Let’s see what the Euro monthly comes up with on the December 5th release. There is a bit of a late November forecast barrier for getting the mid into late December patterns correct. Since we can go back to most years at this time in the long range forecasts and watch numerous changes as the calendar actually gets into the first 5 days or so of December. Plus we have the backdrop of only 3 Decembers in the last 14 years that lead to major I-95 snowstorms since 2011. So December has faced some challenges for the snowfall after having 7 out of 11 snowy years between 2000 and 2010.