After a chilly regime over the past week 7-10 days, our pattern is different this week and possibly for most of November with the flow turning westerly rather than northwesterly (more of a zonal flow). This shuts down the cold maritime-polar air flow in which we’ve received a ocean modified Greenland source air mass. A purely maritime flow returns this week.

+NAO/AO Fits My Late Autumn Idea, Presents Greater Chance For Real Cold Just Weeks From Now!

In yesterday’s post I explain the UK’s impacts from +NAO/AO and while the arctic air retreats, pieces are left behind but remember with the reload now over Greenland and passing lows able to tap this source, we can still get cold spells. This setup is important when looking at the BIGGER weather map and not just focusing on when the cold and snow will hit. I will continue to hammer home the point that by reading these posts, I want you to understand the WHY and not just the what.

Too many out there don’t want to see the big picture. Refuse to look at climate history and what major global players such as the ENSO, PNA, QBO, ocean temperatures and other indexes can have on our weather pattern. Many lean on either daily model runs, long range models and the NAO/AO. These are all very good but don’t always give us the answer. I had my winter ideas long before I looked at any seasonal forecast model. They’re often more confusing and change with time.

As for the current pattern, I want to show you what the atmosphere must undergo in order for the pattern to evolve and more importantly, so we get that noteworthy arctic outbreak before Christmas. It takes time and for those wishing for cold and snow like myself, patience is required.

After all, I would hate to see a weaker, EARLY season cold spell which lasts 2-3 weeks, than seeing the right setup through November but sets the stage for a much stronger and more sustained cold period in December with return episodes in January. By getting the block in winter and not autumn means the cold which comes down will not only be mature but will moderate less because we are at the point where days are shortest, nights longest and the sun angle and strength is at it’s lowest. It is these points I keep trying to make.

Many out there who are wishing for an ice age November might as well wish for a warm, wet and windy winter in my opinion. The arctic reservoir wouldn’t have time to reload and build an intense, widespread area of frigid air. What would likely happen if we did get that cold November, perhaps early December period would be, a system reload right in the heart of winter which would support a mild, westerly pattern with cold trying to reload over the arctic. The weak Nino does not support early cold and anytime we do get that cold November, we usually don’t get a cold winter.

I have also covered with you the fly in the ointment with my November idea and that was, with the strength of the cold PDO and warm AMO, this MAY have lead to a colder November than I originally thought, however, with the onset to a +NAO, these ideas appear to be ok. Could we see a late November turn to cold? That cannot be ruled out. A lot will depend upon who long the NAO/AO stays neutral or poisitive. Given the long term trend, that may not be all that long if I am being honest.

Believe me, this setup now, means we should see lots of fun and games during December.

Once NAO/AO Goes Positive, May It Not Stay That Way Like Last Year?

Why do I strongly believe that once this NAO goes positive, I see it returning? After all, once this flips, may it not stay that way like last year? We only have to look at the good correlation between abnormally warm North Atlantic and the stubborn -NAO trend over the past 10 months. The NAO is bias negative. At this point last year, it was bias positive and remained that way much of last winter. We only need to look at last summer and where the mean Azores ridge was positioned.. this year, the Azores high is further west with the mean trough, positioned over the UK.

A Positive NAO/AO Doesn’t Rule Out Cold & Snow For The UK

My mission to you the big picture and explain what’s going on. Anyone can read a weather map or model. Too often do we see folks jump from one model to the next but here, I want to try and shed light on an approaching pattern change and development BEFORE the charts show it.

This current return to positive is very important for our pattern in about 4-6 weeks from now. Remember, a positive NAO/AO DOES NOT MEAN we cannot see cold and even snowy weather, what is does mean however is we have a very fluid and progressive pattern. Without the block or stone in the water, the air is allowed to free flow, so any warmth or cold is short lived, this also opens the door to stormier weather which I expect to see over the next 2-3 weeks.

The role of the lower heights and reload of cold over Greenland also play a significant role in the UK pattern. As embedded lows cross the N. Atlantic, their circulation taps some of this cold which intensifies the storm before striking the UK. Mild air surging north ahead of the storm’s cold front gets proceeded by a slap of cold on the backside. This was the setup which brought a snowy period to parts of the UK, including large parts of Scotland last December.

Coldest Air Yet For Greenland Next 10 Days

 

While we’ve seen temperatures get down to -50C/-57F already, models suggests colder in the next 10 days. Bare in mind that we’re progressing towards true winter and conditions are becoming much more favourable over the sun absent far north, for cold air production. Very low thickness values over Greenland support temperatures of -60C, this along with the intensifying arctic pool which will support the perfect reservoir in the weeks to come to come south once that NAO/AO flip back to negative occurs.

The wetter, windier process kicks in tonight with windier weather accompanied by a batch of rain, which will spread south over Scotland tonight following a cold, frosty start. So, as stated in your bonfire forecast, be sure to wrap up warm as clear skies and light winds through the first part of the night is sure to support a frost for many. The frost is sure to set in quickly after sunset for much of interior Scotland and Northern England. Later for the Midlands and South.

A series of systems will bring periods of wind and rain through the next 7 days.