As February and meteorological winter 2021-22 has come to a close, it’ll likely be remembered for it’s disappointing lack of any real winter.

Winter’s opening month brought all but a tease of snow and cold during December with hopes held high only to see ‘winter’ stay mainly over the continent. After a record warm New Year, much of January was dominated by an unusually persistent blocking high bringing very quiet, stagnant, monotonous weather but this high did bring quite cool conditions to England and Wales despite never taping any cold sourced air. Probably the most exciting part of winter came late with a stormy 2nd half to February. This also saw the biggest and most frequent ‘disruptive snows’ to mainly Scotland.

February will go down as one of Europe, UK and Ireland’s warmest on record.

For Europe as a whole, December was cold in the north, mild in the south, this reversed during January while all areas we’re mainly warmer than average in February.

Interestingly for the US, December was warm (record warm) while January saw a flip to cold while in Europe, the opposite took place with a cold December giving way to a warm January, especially across the north while the south was cooler than December.

2m temperature anomaly by month for the Northern Hemisphere

December 2021

January 2022

February 2022

Past 90-day temp anomaly

A weak stratospheric polar vortex during autumn 2021 led most of us into thinking the cold was coming and it would be a big winter featuring a major SSW pretty early on. The weak vortex likely led to the cold November and December over Northern Europe anyway with a cold, snowy run up to Christmas on the continent but high pressure and nagging Atlantic influence left the UK on the edge of the chill.

In January, the Pacific-North America teleconnection kicked in leading to a colder January for North America compared with December but due to a +AO/NAO (Arctic and North Atlantic Oscillation), above normal high pressure kept cold sourced air away from the UK and Northern Europe in January.

During an unusually benign January dominated largely by higher than normal pressure, the polar vortex strengthened, initially within the stratosphere but eventually this influence connected with the tropospheric polar vortex, this led to one of the warmest February’s on record along with a 3-week spell of very active Atlantic storminess for NW Europe.

As we step out of winter and enter a new season, the stratospheric polar vortex is now in a renewed weakening phase although there is no true indication of a SSWE taking place.

While stratospheric developments are unlikely to effect the weather pattern during MOST of March, the MJO may play a role. The ‘enhanced pulse of convection’ within the tropics appears to be coming back to life and set to progress eastwards from Indian to Pacific Ocean as can be seen in both charts below.

MJO

The re-invigoration of the MJO (Madden Julian Oscillation) may help the weakening of the polar westerlies and allow suppressed mid-latitude ridging to begin building north and replacing low pressure with high pressure over the arctic. This return of above normal heights may be the reason for the weakening of the polar winds but it’s hard to know who’s driving what.

Either way, the MJO is coming back to life and this may help bring more blocking and cooler weather back into the UK. The models including the GFS ensemble below show a Scandinavian high developing and the ensemble sees a below normal day 6-10 before the Atlantic returns.

Latest GFS ensemble

500mb height anomaly

Day 1-5

6-10

11-15

2m temp anomaly

Day 1-5

6-10

11-15

With no major weakening of the TPV (tropospheric polar vortex), the westerlies, though may weaken for a time, are likely to re-strengthen week 2 and or week 3 of March with the return of the Atlantic.

Stratosphere-Troposphere

While there’s warming up at 10hpa (upper stratosphere), this doesn’t necessarily reflect the lower stratosphere and troposphere.

However, when you see downward energy transfer (warming) from 10 down to 50, 70 and 100hpa, that’s when we pay attention. Often, where the core of warmth at 50hpa set’s up, that’s often where the positive at 500mb will go to.

10hpa now

168 hrs

240 hrs

Here’s the same time frames at 70hpa

Now

168 hrs

240 hrs

While by no means a solid outlook for cold, this certainly provides me with enough evidence to suggest a possible ‘west based’ -NAO within a -AO background towards the final week of March and prior to this, the possibility of a colder, high latitude blocking pattern initiated by the eastward progression of the MJO.

The above also hints at a chilly, blocked April.

CFSv2 suggests a blowtorch for March 2022

Tags: featured, monthly-outlook