What do you make of this?
http://www.ukweatherforecast.co.uk/uk-winter-201415-weather-forecast-predictions/
Originally Posted by: tallyho_83
Interesting to see the El Nino Modoki being considered, as that has come up a few times in recent months as a potential driver of high-latitude blocking this winter.
Prior to December 2010, there was a dramatic switch from an El Nino Modoki to a strong La Nina. The atmosphere might have taken a little while to catch up with that change, so perhaps that El Nino played a role in generating December 2010's extraordinary blocking pattern.
Currently, the long range models are generally going for a lot of UK-trough action this coming winter. Until that high latitude blocking started being modelled, it was looking like another mobile pattern for the winter, in fact similar to last winter, with the storm track south of normal but not tending to slow down enough for more than transient cold spells.
Increasingly, though, the outlooks are showing the potential for the pattern to grind to a halt, with stalled low pressure systems and blocking to the N, NW and/or NE having a direct influence on the UK's weather.
The negative 500m height anomalies haven't really shifted south much in response, but they look sufficient for some interesting storm tracks, as surface lows often begin life somewhere to the SW of the associated 500m troughs, and could face strong resistence from blocking highs to the N and NE, perhaps pulling cold continental air into the mix... with a bit of luck.
The SST-based prediction is particularly interesting, as I believe that the current situation of anomalously low SSTs around the Azores and anomalously warm SSTs to the SW, S and SE of that region has been a primary factor in driving trough development in the middle of the North Atlantic over the past few months, producing the frequent Atlantic trough + Euro/Scandi High combinations that we've seen.
Take that on into winter, add a driving force to enhance the blocking from Greenland to Svalbard, and you've got a recipe for storms tracking into Iberia/the Med. and interacting with cold continental air near or over the UK.
The presence of blocking across the NE U.S. is a total contrast to last winter's setup.
Another factor is the QBO, which was westerly last year and detrimental to blocking, but looks to be easterly this year, favouring blocking. I can't pretend to understand the mechanisms of this at this time though - it wasn't a part of my studies this year. Sounds good for a cold winter though
With all this in mind, one has to wonder what reasoning lies behind the Met Office ensemble mean prediction posted a couple of days ago. Or is it just a bit behind on developments? I guess next month will tell!
Notice average or cooler than average over N. Atlantic for the majority of the time!? - Run the sequence from 2-4 months 3-5 months and to 4-6 months:
http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean
Originally Posted by: tallyho_83
That looks like a continuation of the current SST anomaly pattern, as I've described above
As a bottom line, it seems like a lot of factors are looking to be pretty much the reverse of what we had last winter. Could we therefore see a reverse of fortunes here in the UK? No guarantee, but promising to say the least!
Edited by user
23 September 2014 10:37:09
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