Winter/Spring 2013 (Model Output Discussion)

Personally I would have gone -18.6C

I even saw that -20C article with two months of bad dandruff on twitter, it is everywhere. It is like a bad virus.

November remains on target to finish cooler than average after a cooler than average September and October. The coming days will see a rise in temperatures and a respite from the overnight frosts of recent days. Temperatures will dip again later this weekend and into next week, while next will also be more unsettled than the coming days will be. From 12 onwards, our weather will be dominated by the Jetstream with blustery southwesterly winds and heavy showers, interspersed with cooler, blustery conditions from the W or NW. There is no sign of any significant wintry spell at this point.

The below image features 850hpa temps (temps at approx. 1500m), 500hpa temps (temps at Approx. Altitude:5600m) and precipitation levels, as forecast in the latest run of the GEFS weather model.

pauldry wrote: »

Mild and dank but a blocking high could rescue us in December if we all get together and blow out to sea.

Could happen sooner, Paul. The last week has seen the GFS in particular struggle with the position of atlantic and euro highs. The jetstream has also been quite sterile in recent weeks and it will not take much for a massive flip to take place in a short period of time.

Is it just me or whenever somebody mentions cold, people say that it should all be taken with a pinch of salt/long range forecasts aren't reliable etc etc.

But then when the signs change to a mild outlook it's all doom and gloom and nailed on to happen?

Impossible to tell with any level of certainty at this early stage what weather this winter will bring/

DOCHARCH is correct. Our default climate is mild and often unsettled. There is very little to suggest (at this point) that we will see anything else this winter.

For cold weather enthusiasts, the meteorological winter lasts from Dec 5 through the early days of March so there is a long way to go before any conclusions can be drawn on the winter as a whole. The coming weeks will indicate what the first half of the winter might bring us.

The AO is unlikely to stay in positive territory into the fourth week of the month if you take its trend from the past four months (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_mrf.shtml). This will allow for a reload of cold. The jetstream is much more sterile than we have become accustomed to so any flood of cool air south from the Arctic in late Nov/early Dec very well could introduce much colder weather to this region. There are a multitude of factors that must come into play to allow this to happen including ridging to our west/Greenland (serves to divert jetstream) and/or ridging over Scandi/western Russia). As I already noted a few days ago, the GFS in particular is having considerable difficulty in determining the positions of High Pressure systems in the Atlantic. Ominously the Azores High, which was a major contributory factor to last year’s mild winter, is lurking in its familiar position. This will need to track further NW toward Newfoundland/Labrador to reduce the effect of the jetream on our weather. Keep an eye on that here http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=0&mode=3&carte=0

I appreciate that there are many ifs, buts and maybes in what I have outlined above. This underscores the building blocks that are required for sustained cold to affect this region. Hence, why there is a very low confidence factor associated with any long range predictions.

Nice work there Mindgame