FI Charts ( T120+ onwards) Spring 2020 **READ MOD NOTE IN FIRST POST**

nacho libre wrote: »

It has the whiff of a late April - early May sometime back in the '90's. I remember looking out the window in to see snow fall courtesy of a potent northerly. I'm not saying the same will happen this time, but as you say it will feel very unseasonal if it comes to pass.

Either 1995 or 1996 if I remember correctly. Snow showers in May, often while strong sunshine, much like today, was shining!

A very impressive arctic high on some models runs. It's just typical we'd get these charts at the wrong time of year.
Looks like the Scottish ski resorts could be in for some snow during the second week Of may. I fear that we could end up with low pressure systems hovering over us as we go later into the month. Still, i'd take a lousy May, if it meant we ended up with a decent June to follow.

Models do seem to be picking up on something towards the middle part of May. This is current GEFS run showing 850 hPa temp anomalies:



EPS showing something similar also, but I also recall that both these outputs showed something similar at the beginning of last month that never really materialised in the end. Also, I read recently the model accuracy has fallen through the floor since aircraft data (which is fed into model output) has become ever more scant. Not saying that the models are wrong again this time around, but this is something to keep in mind when looking at longer range data maybe.

There is a possibility we could set up an Omega block next week with low pressure stuck in the Atlantic and to the east of Europe courtesy of a northerly shift of the jet stream. Omega blocking highs are notoriously difficult to push for those that do not know and our driest summers all contain them. As we seen from Summer 2018, models tend to be too progressive with omega highs. I think this is even more the case this time around with problems like less weather observations from weather balloons due to the pandemic and we are getting close to the hurricane season also which will mean more spanners being thrown into the mix. In fact, there is an area of low pressure near the Bahamas right now that has a high chance of becoming a subtropical cyclone by the weekend. Don't expect model certainty to become much better.



We actually already had an omega high this spring too that brought the March-April fine and dry spell with only a few blips due to changes in the positioning of the anticyclone.

With the current situation, regardless of all the rain we received over the summer to winter period prior, I think the prospect of an omega high is very bad news. The lack of rain from this spring is one thing but the use of excess water due to Covid-19 demand just makes this issue more apparent. A relatively wet summer might actually be a good thing in that regard or else I see a hosepipe ban being put in force which seems crazy to think after such a wet August, autumn and February.

Slightly off topic for a second but I will not be releasing a summer forecast this year (my most recent forecast was in fact Summer 2019). I won't say I have given up on seasonal forecasts but I do not plan to bring them back any time soon due to loss of interest and life being busier nowadays in general. However, the equatorial Pacific continues to cool down a lot. If this keeps going on and on, we will be in a La Nina by the end of the summer or the autumn which could mean a bad omen if it's warm and dry weather you seek. ENSO correlation with European weather is hypothesis at best but the rapid transition to La Nina and summers here have one of the better connections.