Thoughts on Autumn, Winter and Why There Was No Winter Last Year!

Written by on September 28, 2012 in United Kingdom & Ireland with 0 Comments

I have stated multiple times already about the fact that the UK/Ireland autumn should be warmer/wetter than usual when all is said and done at the close of November but that does not mean we can’t see cold spells nor accompanied by snow. Like in 2009, I think we should see wet and stormy conditions with BACKSIDE cold coming down following stronger than normal lows. I have raised concern over 2-3 MAJOR storms with pressures below 960 rocking us between now and early December based on how warm the North Atlantic is, what we’ve seen in the last 3 months with a stronger jet and deeper lows and the correlation between recent summers (similar to this past summer) and the following autumn. Remember that our recent ‘wet summers’ have been followed by wet and at times, stormy autumns. The amount of available energy is going to increase as the cold builds over Greenland and the north while warmth fights on to our south and you’ve got these two meeting over abnormally warm SST’s.

The recipe is there for flooding and some wild storms. Right now, like in autumn of 2009, I don’t see so much of a blocking pattern early but that should come by the end of November but brief dips into a negative NAO may bring us brief cold, even snowy spells. That can’t be ruled out.

Once the atmosphere transitions from autumn into a winter mode, it’s then I see the feedback of those warm waters that lead to blocking highs. Given just how warm the waters are over the Northwest Atlantic and surrounding Greenland, that is where we should see strongest positive height anomalies. We sould see SIGNIFICANT blocking over Greenland, eventually extending over the pole. This could lead to a very tough winter for the Eastern US and Western and Northern Europe with ridging and milder conditions in the east. For a true arctic outbreak and repeat cold waves, we want to see a period of at least 8 weeks of positive AO/NAO which allows the building of the arctic reservoir, then a sudden shift with a major stratospheric warming event and all that cold spills south.

Why the concern over flooding and severe storms this autumn?

Check out the current SST’s with the same time in September 2009 when we saw major rains and strong storms later in the autumn.

This year.


Notice the similarities?

Yes, this year the North Atlantic is warmer and the North Sea is cooler compared to 2009. I may be wrong with this as in some respects I hope the feedback to blocking rather than feeding the jet and storms doesn’t kick in prematurely, but that WARMER water SHOULD argue more energy and moisture available for release to the atmosphere during the transitionary period (summer to autumn to winter and by driving cold air over top of this warm water, this could and I believe should fuel stronger, wetter storms for the UK with November a month of particular concern in terms of flooding and wind damage as thermal gradient should be greatest. After November, cold is bias and warmth has less effect further north.

Heat contains energy and the warmer than normal water means more available energy and MOISTURE to feed storms. That is really why we’ve seen not only this summer but really most summers been considerably wetter, cooler than normal since 2007. The warm Atlantic as well as the 2007 flip to cold in the Pacific has flicked a switch in the overall, long term UK summer pattern. The back to back La Ninas meant drought in the Southern and central UK but it was a real soaker in the north. The back to back La Nina’s STOPPED what would have been a UK-wide washout last year and in 2010 too and this in turn caused a non-winter last winter with dry soils leading to enhanced ridging which stopped cold air which shiovered Europe from coming west. Had it not been for the back to back la ninas causing drought and thus leading to blocking over us, we would have had a 3rd nasty winter or at least 2-3 week period of winter in 2011-12. What flipped the cycle of back to back drought in the past two years? The decay of the la nina and the return of the el nino. Something I regret not seeing beforehand and if I did, instead of calling for a 2 scenario summer depending on spring rains. I would have called for a wet to very wet summer simply in account of the el nino return.

Pacific flip in 2007 and continued warmth in the Atlantic is the cause for soggy summers and very wet/stormy autumns

It’s really the flip in the Pacific, combined with an already warm but increasingly WARMING.. North Atlantic that has and will continue to lead to wetter, gloomier conditions during summer and autumn in the UK. As for winter, like in 09-10 and 10-11, that warm water which brings gloomier in summer/autumn, can lead to more winter blocking with colder/snowier for the UK.

Why no chance of an early winter blast through at least the first 10 days of October?

Take a look at the NAO!

It’s going POSITIVE. Forget what’s happening over North America with the recurving typhoon and the cold blast looming there in the 7-14 day period. That isn’t because of the NAO, it’s because of the pattern in the Pacific and positive PNA (Pacific North America Pattern) which promotes a strong west coast ridge, central and eastern trough!

Looking at the next 7 Days

Looking quickly at the weekend and into next week and the unsettled theme continues with at least two more lows lining up over the Atlantic that will present us with that all too familiar wind, rain and showery regime.

Tomorrow will see more heavy showers and blustery conditions then Sunday sees another low (currently over the NW Atlantic) which will swing a cold front through Sunday night bringing another batch of wind and rain, turning showery with a chilly NW wind into Monday.

GFS surface and precipitation chart for tomorrow (Courtesy of WeatherOnline)


 Last gasp sunshine & warmth to end next week?

Interestingly, both the GFS and ECMWF show ridging at the surface and aloft at the end of next week so we should see a last gasp taste of summer-like weather. Warm sunshine for most!

Here’s the latest ECMWF chart for next Saturday.

Tags: , ,

Follow us

Connect with Mark Vogan on social media to get notified about new posts and for the latest weather updates.

Subscribe via RSS Feed Connect on YouTube

Leave a Reply