In the coming days, you'll see many Velocity Potential & Madden Julian Oscillation (MJO) plots on #wxtwitter. Here, I show what they often entail for Atlantic tropical cyclone (TC) activity. Notice the Atlantic is most active (🔴) when the MJO (🟢) reaches Indonesia (phase 4)

-NAO is notable throughout, but becomes especially strong at ~ 7-8 day lead time. This may be key for deflecting the storm track south over the CONUS, enticing the upper trough out West to dig more. This is often a fail mode of many medium range modeled snow events in Southern NM

While it may seem like a new weather app crops up all time nowadays, I have to say that Pyre Weather is one of the coolest, synoptic meteorology - climate dynamics tools that exists and as you can probably tell, I’ve spent way too much time using it the past few days 😅

It’s unusual to see the -TNH pattern (Hudson Bay ridge) crank up so early in winter like this. Usually takes til at least Jan or Feb for the -TNH to be this pronounced Only 1877, 1987, & 1997 seem to be in the same galaxy over N America as the latest EC46 & CFS forecasts for Dec

Time to answer the question: What can an early-November Polar Vortex collapse (SSW) do to Winter 2026/2027? 🧵👇 These maps are not a forecast or actual temperatures. They show the DIFFERENCE between winters with an early-November collapse and winters without one, in the same El Niño+wQBO setup. Since there is no real observational data with such an early SSW and nino/QBO combo, I decided to look for data in two independent model sets: 🔹 Climate models (CMIP6, 80 runs): 32 model winters with an early collapse vs. 565 without. All of them with a strong El Niño + westerly QBO, like this year. 🔹 ECMWF SEAS5 seasonal forecast hindcast (1981–2024): 109 forecast members with a collapse vs 444 without. Each is compared only with the other members of the same forecast, so the ocean and El Niño/QBO are identical. Why 32 vs 565 is ok in the climate models: the big group is the baseline, or the normal El Niño winter without a collapse, as all are the same base state of strong Niño+wQBO, not random winters. It is supposed to look "average", and subtracting it leaves only what the collapse adds. The small group only makes the result noisier, which is why the dots mark where the difference is statistically significant. December is where both agree: 🇺🇸 Central & Eastern US 1–3 °F colder, while northern Canada around Hudson Bay runs milder 🇪🇺 Scandinavia & NE Europe 1–2 °C colder, with high pressure to the north and lower pressure over the Atlantic After December, the signal weakens. The climate models fade it out by January. SEAS5 keeps some cold over the central US and over Scandinavia/eastern Europe into January and February. Bottom line: an early collapse mainly loads the dice for December. It does not lock in a cold winter. But these are just climate simulations, not actual forecasts, as said, only meant to find an underlying signal. Use these with caution, and do not present them as an actual forecast, as they are not. These show the difference in signal, and if the mean base anomaly is +3, a -1 difference still leaves it at +2, for example. For phase 2, I am planning to use a larger CMIP6 set, and I am also thinking of making my own custom simulations, as this is a fascinating situation in development. @judah47 @RyanWeather @webberweather @TWOweather @bam_weather

Great work here by Andrej This shows there’s not much value to a very early Stratospheric Warming Event like we have this yr beyond about December He also shows that in Dec it’s usually not quite as mild as the Super Nino composite (right) over the SE US, not unlike 1997 (left)

Great post by Dave here about the current stratospheric warming event. Highly recommend giving Dave a follow if you’re interested in #S2S (Subseasonal to Seasonal) long range weather forecasting. Easily one of the best ones out there.

Following up on my previous announcement that gsdmsolutions.com will soon feature a page devoted to SSW events and the causal chain in which they’re embedded, I have created a new free post: understanding the predicted SSW, from cause to consequence. El Nino’s eastern Pacific forcing —> wave train —> Russian ridge —> SSW event. Yet the subseasonal forecast is “El Nino-fueled” mild weather, nearly the mirror image of what often follows SSW events that impact tropospheric winter weather. gsdmsolutions.com/blog/ssw-n…