bluewave

The Pacific Jet is still Niña-like in strength. Notice the trough correcting closer to the Aleutians for the start of December. If the models continue to underestimate it, then the ridge axis will gradually start drifting east in later runs. So it will be a battle between the jet extensions enhancing the ridge and trying to weaken it. Modeling by next week will probably give us a more definitive answer as to where that ridge axis ends up in mid to late December. New run stronger jet carving out trough near the Aleutians with ridge axis into the West Old run jet was weaker with ridge axis further west

1989 was the last white Thanksgiving but we have warmed up quite a bit since then.

It’s interesting that we may have both found our way to the Pacific blocking through different means. I was mentioning the mismatch potential back in October with the high amplitude MJO 5 leading to less MJO influence early on in December like we are seeing now. But I wasn’t sure whether it would manifest in December as +PNA, -EPO, or -WPO. It’s good that we can use different approaches and come to a roughly similar conclusion of more blocking on the Pacific side to start December than recent years. The complicating factor I mentioned is that the mismatch is occurring against a much weaker La Niña state than 2020, 2017, and 2010. So we may see more of a competing influence going foreword than those stronger La Niña years. It’s possible we may see a stronger MJO influence later on which would add another competing influence to the mix. It will be fun to see how it goes.

Yeah, if the +AAM influence starts to wane with a resurgent La Niña cooling and EWBs then we could see this pattern start to shift by mid-December as the Pacific Jet tries to intensify.

Probably due to the actual temperatures being cold but nothing too extreme for the first week of December. It’s still early in the season and we are starting from a very warm base state this fall. So it will take time to build more impressive cold. We usually have to wait until we get further into the winter like in 20-21 to generate a more impressive Arctic outbreak. 2021 record Arctic outbreak

It’s been a while since we have seen this much model spread at 84 hours. The Euro has a more consolidated storm. The GFS has 2 weaker waves and is strung out. Still warm with both along the coast but the Euro would give us heavier rains which we need.

It’s also difficult to compare to the distant past since we don’t measure the snowfall the same way as we used to. https://news.ucar.edu/14009/snowfall-measurement-flaky-history

It’s being discussed in the main forum in the La Niña thread since we don’t have a December thread here yet.

It looks like the Great Lakes should open for business first.

The higher temps than forecast are steepening the low level lapse rates leading to some peak gusts over 40.

Morristown won’t be getting anywhere near -10 in early December. They have warmed up quite a bit since 2002. That was the last time Morris County saw 0° cold first week of December. But as I said the -EPO +PNA this year won’t have the real Arctic cold to work in those areas first week of December coming off one of the warmest falls on record across North America. Data for December 1, 2002 through December 7, 2002 Click column heading to sort ascending, click again to sort descending. BOONTON 1 SE COOP 15 CHATHAM 2 W COOP 10 LONG VALLEY COOP 0

It will be interesting to see if the records committee in NJ can confirm the new state snowfall record for November.

We will need to extended this pattern into mid to late December to get any noteworthy cold vs past events around NYC with how warm the Lakes and Eastern Canada are starting out.

Yeah, Newark is on track for one of their latest first freezes. Frost/Freeze Summary for NEWARK LIBERTY INTL AP, NJ Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 1985 04-10 (1985) 30 12-02 (1985) 30 235 1979 04-08 (1979) 31 11-29 (1979) 32 234 2016 04-10 (2016) 31 11-28 (2016) 32 231 2010 03-27 (2010) 28 11-27 (2010) 32 244 1978 04-03 (1978) 31 11-25 (1978) 32 235

I am showing the model output which is forecasting a colder pattern for early December but not as cold as would be suggested by what has occurred with those teleconnections in the past. You keep bringing up the term agenda for some reason. If I have an agenda at all it’s trying to figure out the actual pattern. If that triggers you in some way look within yourself.

First, the seasonal long range model forecasts for December issued back in early November or even October have seldom been correct which everybody knows. Second, I was mentioning back in October that the early MJO indicator was indicating the potential for a mismatch in December like we saw in 2020, 2017, and 2010. I also stated that we would need to wait until we got closer to December in order to see if it would work out. So this is not a complete surprise. Third, I have no idea what you mean with a term like agenda since I never met a thermometer that had one. Finally, all my posts and forecasting techniques are big data driven where perspective is key. If perspective to past patterns are an issue for you maybe you need to look within and see where the resistance lies.

Hopefully, the more amped up Euro and CMC with heavier rainfall are closer to the mark than the weak and strung out GFS since we need the rainfall.

This is going to be a warmer -EPO +PNA early December pattern than we have seen with similar teleconnections in the past. It was the warmest fall on record for many so the source regions will take time to cool. You can see the teleconnections can generate cold at 850mb but the surface departures aren’t forecast to be as cold. We would need to sustain this pattern deeper into the winter for the surface departures to catch up.

With a little luck the systems correct more amped so all of our stations can easily avoid the driest fall on record. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 2.81 8 2 1931 4.21 0 3 1964 4.93 0 4 2013 5.02 0 5 1941 5.04 0 Time Series Summary for NY CITY CENTRAL PARK, NY - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 3.87 8 2 1908 4.00 0 3 1909 4.67 0 4 1881 4.93 0 5 1931 4.97 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 2.94 8 2 1965 3.31 0 3 2001 4.02 0 4 2013 4.86 0 5 1973 5.38 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 2.94 8 2 1965 3.31 0 3 2001 4.02 0 4 2013 4.86 0 5 1973 5.38 0 Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT - Sep through Nov Click column heading to sort ascending, click again to sort descending. 1 2024 2.73 8 2 1964 3.68 0 3 1965 4.16 0 4 2001 4.20 0 5 2013 5.55 0

Chances are we see a moderation of the pattern by mid to late December since we haven’t had a cold start to finish December with every week colder than average since 2010 around NYC.

Very impressive Nino 1+2 warming as they were able to surpass a warm minimum record in Peru from the super El Niño in 97-98. With sea temperatures unusually high off our coast, minimum temperatures are responding to this warming. The airport at #Lima - #Callao saw an overnight minimum of 19.2°C. This is the highest value for the date since the great #Niño of 1997-8. We are just 4 weeks away from the start of summer and it will be a question of the struggle between the cold and warm Kelvin waves with the winds blowing at low altitudes; whether the warming survives or not. If it survives a warmer than usual summer, that's something to bet on.

It will be an interesting test of what occurs during the 2nd week of December. On one hand the EPS weeklies back in 13-14 and 14-15 were continuously trying to break the ABNA pattern down beyond 15 days. The models kept pushing the pattern moderation back in time the closer in we got. But the Pacific Jet from Japan to the east was much weaker those winters. The model forecasts have some pretty impressive jet extensions forecast in early December near Japan. So it will be interesting to see if they can sustain the pattern or cause it to relax.

My guess is that the December forecast will be determined by jet extension and retraction dynamics. Sometimes these big WPAC jet extensions can sustain an existing pattern like we are seeing in the forecast for the first week of December. So it would cause the pattern to reload for the 2nd week. But the wild card with all these jet extensions is that they can also reverse a pattern. So the thing to watch in later runs is whether one of the jet extensions can cause the ridge out West to drift into the East by mid-December.

Thats OK for areas further north in the Upper Midwest into Canada closer to where the Arctic highs are generated. But those air masses moderate quickly in early December coming south with the lower snow cover.The Great Lakes are also near record warm after the warmest fall on record for many areas. So while we will see a colder start to December , the air masses will moderate coming east of the Great Lakes. Cold air moderating coming east of the Lakes with coldest departures going to the south

This October into early December MJO forecast is similar to 2020 which I mentioned with the high amplitude MJO 5 both Octobers and weaker MJO 5 in December before going into the circle.