KyleHenry

Yeah ECM 00z is struggling at days 7 8 9 and 10 regarding the split details as they were clearly indecisive.

Most up to date that I have access to via FU Berlin. It matters.

For what it’s worth, final confirmation has to be sealed by the 150hPa otherwise HP will never hold in place. What do you know? it does this time. If TPV vacates east Asia and turns slack in that area then this episode will be colossal in terms of cold/snow but also brutal.

I believe that the GFS is reflecting its observations on the SPV’s return to the default position, after current displacement. Therefore it has a habit of speed running the modelling dynamics. At 144z it predicts the TPV to move 80% into Newfoundland and 20% into Kara sea. Not only that it has multiple LP spawning off Greenland in a highly condensed area. UKMO has the TPV split 50/50, less congested with slacker upper air. Anyway we will remember this moment in a weeks time and decide how correct the GFS was/ wasn’t l.

Both but by a different mechanism,the PV displacement (SSW or close to reversal) permits the Arctic high to form by moving the PV off the default position. The Aleutian low creates the brake for the WAA from the Pacific into the Arctic circle. Then the Arctic High is allowed to fill the vacant space. PV needs to reverse for the Trop AH to gain height in the target zone.

There were hints that the TPV could fall entirely into Europe. Which would be an atomic hit of cold air if that occurred. I remain hesitant on that outcome for now. Whereas normally 70/30 and the seventy going into North America. Anyway the movement of the TPV is still to be resolved but the predicted timing 9/10th Jan for UK cold/snow prospects still holds for now. The TPV pattern is there on both models, which would align with -40C expectations for Scandinavia.

Very surprising. I was looking at this. It’s a pivot point as to how the TPV NE Canada will dissolve in terms of where and how much the cold air will move to.

I can see his reasoning. Yes it 240z but it’s based on pattern recognition of PV displacement. Red arrows indicate expected movement for approximately 9th Jan. HP up into Greenland and TPV dropping into US and Western Europe. So it’s all eyes on UKMO and ECM next two days for confirmation.

Blue what’s the EC46 showing for around the 13th Jan at 10hPa?

I’m staying grounded. Brake pad glowing is enough for now. TPV doing its own thing next.

Chart of the day.

Many people are forgetting the previous lessons that we’ve learned throughout the years, regarding the process and the models reactions at the tropospheric level. 1. The GFS sees the signal first and throws out huge cold charts in FI. 2. For accuracy, the model viewer must switch to ECMWF. That time is now. Still look at the GFS for fun. It will realign approx 5th January. what should we be expecting as of now? Formation of -AO only and migration into Arctic circle . Any extreme cold weather for the UK wouldn’t be physically possible until after 10th January in terms of PV displacement/split. It’s just too early, yes there could be brief north westerlies in-between now and then. Personally I’ll be looking at ECMWF from 2/3rd January. Remember -AO first, then cold air into North America which allows HP blocking into Greenland. Then us.

Pacific Ocean is the source driver. Westerly wind burst towards Indian Ocean. Kinetic energy goes up high in atmosphere to create the EAMT event if the timing is right which leads to warming in stratosphere. Then it must dominate the PV and reverse the air flow. Results in PV displaced and allows a -AO which is HP Arctic circle. Creates the braking system to allow High latitude blocking. Simple heh!

Understandable if just following the daily model runs and awaiting a significant change to happen. The problem being, it’s just too early and can only lead to teeth gnashing. What is the time line for potential change? Stratospheric warming process begins 31st December. Expect around 3rd/4th Jan for strong -AO to form and take position over the Arctic circle. The pattern is always the same, Cold Asia. Cross polar flow to create cold North America. Estimated to be around 5th Jan. Then Europe approximately 5-8 days later. -NAO. With high pressure into Greenland. None of this occurs without the SSW. It is still too early to say exact details of a major event. I’m 75% certain it will be, by slightly dipping below 0m/s at 60N.

And so it begins, repeated evolution of Aleutian LP systems, how many and for how long matters in terms of creating enough dampening to allow HLB to develop. Estimate to be 14-17th January. This winter seasons pattern has been a repeat and rinse pattern. No coupling between TPV and SPV, therefore both have been allowed to act independently of each other. If no coupling occurs after this event then a repeat in this process will occur again in late February. Like mid November 2022, the Aleutian LP created the breathing space for HLB between Greenland to Scandinavia. The models pushed for Scandi HP and an easterly when the result matched the anomaly chart predictions of Greenland HP. It is this process of Aleutian LP and Scandi HP which is the base foundation of a possible SSW. Attaining a SSW this winter doesn’t matter due to there being minuscule coupling all season. Next year 23/24 it will matter with El Niño emerging. GFS picked the signal and showed Easterly. Time to focus on ECMWF. Stall of Aleutian LP systems does point towards Greenland HP again. NW Europe cold again by the 17-24th Jan. US to follow from the beginning of February. ( NW Europe could hold pattern for 2-3 weeks again similar to early December. Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4783027

And so it begins, repeated evolution of Aleutian LP systems, how many and for how long matters in terms of creating enough dampening to allow HLB to develop. Estimate to be 14-17th January. This winter seasons pattern has been a repeat and rinse pattern. No coupling between TPV and SPV, therefore both have been allowed to act independently of each other. If no coupling occurs after this event then a repeat in this process will occur again in late February. Like mid November 2022, the Aleutian LP created the breathing space for HLB between Greenland to Scandinavia. The models pushed for Scandi HP and an easterly when the result matched the anomaly chart predictions of Greenland HP. It is this process of Aleutian LP and Scandi HP which is the base foundation of a possible SSW. Attaining a SSW this winter doesn’t matter due to there being minuscule coupling all season. Next year 23/24 it will matter with El Niño emerging. GFS picked the signal and showed Easterly. Time to focus on ECMWF. Stall of Aleutian LP systems does point towards Greenland HP again. NW Europe cold again by the 17-24th Jan. US to follow from the beginning of February. ( NW Europe could hold pattern for 2-3 weeks again similar to early December.

It has got to be said, this prolonged feed of air into the entire region of Iceland towards the Kara Sea is magnificent. Pumping heights up over such a large area unhindered. This is the process that allows the black hole areas seen on the anomaly charts. Very rare occurrence and once this configuration completes, left standing will be an immense HP cell that will maintain longevity against TPV attempts to reform. Then we will see the true dynamics of brutal cold temperatures to NW Europe. At present 11th December looks the target date.

Catch 22, you want 1040 mb High pressure so that when a gap opens during each TPV evolution. Means stronger WAA and more successful high latitude blocking. One of these evolutions will drop kindly eventually. February being the next window of opportunity.

Agreed nothing at that range will develop a sustained cold spell. The rotation of TPV with WAA around the 16th January has potential for something very potent cold wise.

Just discovered yourself a bias flaw in the ECM for future scenarios similar to now. GFS picks up signal early but fails in its timing of the event, this time it has dealt with the block and slow moving low pressures off Greenland much better than ECM. ECM is stronger regarding a faster evolution of the WAA into Greenland and struggles with the slower evolution. UKM plays a tighter time game,hence more reliable.

Observe the pattern, three TPV lobes are forming. SSW will disintegrate TPV to mid latitudes. One will be for Europe, question is how far west it can move.

For those that care to know, this post is for you. The Tropospheric Polar Vortex is a maelstrom, hence the difficulty for models to forecast the precise mapping of it’s movements. Therefore during SSW events you’ve got to look higher up in the atmosphere, when there you’ve got to watch for the formation of -AO in the Polar region. ECMWF 240z from Berlin at 100hPa has the -AO form on the Northern Pacific side of NH The GFS excels at picking up the pattern at range and predicts the TPV bleed across Polar region. This brings the Northern US back into winter proper. The GFS’s flaw exist in timings of the exact movement. Whereas the ECMWF runs approximately 3 days behind the GFS before it nails the exact movements of TPV and the GFS flounders. All I’ll say now is watch for TPV transfer from East Asia into N. America. WWA up via Pacific to form -AO. What happens afterwards can be deciphered by each others level of understanding.

As you say there is no Greenland HP, the absolute destruction of the TPV is the only story in town.

CWB to curve up to Greenland and back towards the eastern US. The lack of TPV and energy contained inside the wave break on the UKMO 168z. HP may not hold for long over Greenland but cold air down through the UK and retrogression of HP towards Scandi a likely outcome.

Charts are showing Canadian warming event. The SPV is being dominated by wave 1 and inside the original Rossby wave process the model believes that it contained a considerable amount of energy. During solar minimum the Stratopause is lower in altitude (Electromagnetic compression) and these waves traverse well beyond the 1 hPa level, which allows the SPV to be dominated. How? Current Scandinavian HP and Aleutian LP at 500 mb level are holding position long enough to allow Rossby wave/s to progress and create this event. Personally I believe we will see a reversal at 10 hPa. There is no Trop/Strat coupling and the Troposphere PV is actively being disrupted. Southern arm of US jet stream appears that it will push WAA into Greenland region and will continue to do so during December. As to what happens following SPV disruption I can’t see yet. In short mayhem.