Snowy Hibbo

RE: Discussions of stratosphere and the big +AAM spike. https://longrangesnowcenter.net/2020/01/22/north-america-on-the-long-term-22nd-jan-2/ The latest blog update for North America (the first of 2020, finally) from my perspective. PNW/BC/Northern Rockies to remain good for the next fortnight, reducing in the second week of Feb. California/the SW/Southern Rockies to improve for the latter half of February (maybe a bit earlier) Eastern US expected to improve for the last 15-20 days of February (2nd-3rd weeks of Feb, possibly into the 4th week) IMO. These impacts may be reduced/weakened by Arctic influence, etc. This is driven by the spike in the AAM via the tropical to extratropical pathway, which then extends the North Pacific jet stream, which leads to Aleutian lows being developed, which signals for -EPO ridging, and ultimately Eastern US troughing.

It’s looking very good at the moment.

Well that's the thing honestly. There's been so so so many posts arguing about the MJO, but at the end of the day, if it doesn't get to the extratropics and the poles, it's impact is rather limited. Again it's going to be gradual. But a positive AAM is a positive sign. Nothing definitive and no sudden equations or conclusions to be made there, but is a hopeful sign. Cautiously optimistic is the best place to be IMO.

Decent rains are on the forecast for the firegrounds, courtesy of the MJO pass and the late monsoon finally arriving: 31mm is about 1.2 inches of rain. 57mm is about 2.25 inches of rain. Not meaning any disrespect as you wouldn’t know, but the Australian is a climate-denying joke. It’s basically if Fox News was an Australian newspaper. Most of the fires that threatened homes in the country were started by lighting. The usual spots got their typical fire-bugs, and were controlled quickly, but the actual major bushfires are all natural fires.

With all due respect, I don’t think relying on a single (strong, yes, long-term, no) MJO pass to deliver 3-4 weeks of cold weather is very advisable. The MJO pass is all over by the last days of the month. Maybe 5-7 days after that, but the Arctic and Stratosphere are both unfavourable. I don’t think it’s sustainable, sorry. We will neutralise in the early days of February (not torch), thanks to the various other factors that also make up the equation in addition to the MJO.

You can’t deny the pattern will be good for the Eastern US for the last two weeks of January, based on the strong MJO pass over Phase 7-8: I don’t see the same support for February, the MJO basically goes dark again after a counteracting opposite MJO signal passes over Maritime Continent and to a lesser extent, the Pacific. The Indian Ocean dominant base state is re-established by the latest EC-46. CFS still plays the weaker Early February card, and perhaps a better late February (next GWO cycle?). But with an uncooperative stratosphere and NAM, I can’t see a cold risk sustained for a month, based upon one MJO pass. I’d enjoy the rest of January while it lasts IMO It should be good.

My latest European snowfall long term outlook: https://longrangesnowcenter.net/2020/01/07/europe-on-the-long-term-7th-january/

This sums up the situation on the ground (Mallacoota, ABC):

The mixture of the +IOD and the SH SSW that induced a -AAO have led to this pattern. A negative Antarctic Oscillation brings us snow in the winter, but brings hot and dry conditions in summer.

Just to add on to this, here’s my latest outlook for North America, discussing long term weather prospects for both sides of the continent: https://longrangesnowcenter.net/2019/12/30/north-america-on-the-long-term-30th-december/ Sticking to the same themes, but just more details, etc.

I don’t really see anything exciting. There is probably something in there during that 6th-9th Jan period. Then you get a -EAMT > Aleutian ridging > Western troughing > Eastern ridging for a week after that. The pattern is up and down, some threats here and there, but it’s largely more of the same, except maybe for that 6th-9th period. The problem is that there’s still IOD forcing, and there’s also some tropical forcing in the MJO domain that may be more conducive to Eastern cold. So you have two competing signals. We have GWO Phase 5, but that will head to Phase 8 in the next week, and then go for another orbit in the neutral/negative phases in the first two weeks of January. This will help make the 6th-9th a reality, but then force Aleutian ridging on a synoptic scale to make for a poor pattern. The stratosphere is pretty neutral, and the best chances of a SSW are further down the road. Then you have to wait for the next orbit of the GWO probably later in January and early February. As I’ve said previously, the base state is going to change slowly, it’s not going to flip all the sudden.

Just a few notes about the East Asian Mountain Torque, we will start with the current status. We are currently in a negative EAMT. I expect a positive EAMT to develop in the next few days to counter the current negative trend for a brief moment. This would add some momentum for the first 10 days of January for the PNA domain. But it won’t last. However from about the 1st to 3rd of Jan, we will see another -EAMT come into play, and this one could be sustained for a while. This is going to reduce momentum in the North Pacific basin, and increase the forcing of Aleutian ridging, and therefore Western US troughing and Eastern US ridging. As you can see in the model guidance, the troughing over Siberia early in January weakens the Siberian High, which weakens our chances for a stronger North Pacific jet stream pattern, and for a strong Aleutian low. Based upon this, I’d forecast Aleutian ridging for much of the month of January, barring an extraordinary constructive interference. The weak Siberian High and Aleutian low also means that any forcing towards a SSW is unlikely in the foreseeable future. Hope everyone here had a good Christmas, and wish everyone a happy New Year.

Well if you don’t wanna want to sound harsh, maybe use some different words. Yes there has been instances of -NAO style patterns this month. and yes the otherwise predominantly +NAO forcing has made for a pretty average pattern. Torch, no. Deep cold, no. Average (ish), yes. Yes, snowfall has fallen, in some places more than others, and yes some people will measure more than others in the same region. Getting semantical about indexes isn’t really helpful either. Nor is using single point data by anyone (this isn’t targeted at one person or a specific group) to prove their conclusion. Do I think this pattern will continue for a good part of January. Yes. Do I think other people are entitled to have a different view. Yes. Will snow fall in early January. Probably IMO. Will a large quantity of snow fall (relatively) in early January. Probably not IMO. Is my opinion subject to a degree of failure, like every other weather forecaster. Yes. It is the nature of opinions after all. I wish you all a merry Christmas, and wish very much for you all to get the snowfall you want.

I believe that they said that there hasn’t been a -NAO event for the current month so far. You are posting a medium term chart/forecast. If you want to call that a -NAO, be my guest, but the reality is that the ridging anomalies are focused in the PNA/North American domain. And below the Greenland blocking, you have a trough with a more meridional, but still fairly amplified flow. So..... At the end of the day, it’s not about the loading pattern, it’s about where these lows and highs actually are.

Not an awful look, but certainly not up to all the hype. Canadian trough, yes. Pacific high, meh. NAO, not so great. GEFS looks better (one might argue it’s like a dream scenario), but less logical: Long line of troughing without real structure, particularly looking out West. And relies on a strong Aleutian Low and a strong -NAO like Atlantic high to hold it all together. It just looks very bizarre IMHO. There might be something in there however. Maybe.