Happy Monday to you all. Hope your weekend was a great one. I am a happy man this morning given the fact that this is another dry week for the UK and perhaps a good sign for later down the road.

As expected the air mass is warming as the cold vortex devorces from the main upper flow and weakens en-route to France and Spain. We have another ridge building over the UK from the southwest which shall keep us nice and settled through the next 7 days. This set-up promotes milder days with temps of 5-9C but nights beneath clear skies remain cold with moderate, even severe frosts over Highland Scotland.

The first half of this week brings sunnier skies across parts of Ireland, Northern Ireland and Scotland while it’s cloudier over England and Wales. Beneath this stubborn cloudcover, expect cooler days with warmer nights with temps holding above freezing.

In the sun and light winds, it’s going to feel nice and pleasant with a nice warmth off that late February sun but rest assured, once the sun goes down, it gets cold quick.

This week continues an amazing drying trend where we appear to have broken the wet cycle which has lasted the best part of an entire year. It’s been largely dry now with higher pressure over us for a good 10 days with little in the way any appreciable rainfall through at least the next 7-10 days. The longer this pattern holds the better it may be for us as we enter spring. What happens now can significantly impact our weather during late March, April and May and what happens in spring shapes what kind of summer we have. In other words, this current dry spell shouldn’t be overlooked, it may be telling us a lot and hinting at what kind of weather we may have over the next 6 months.

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Here’s the latest ECMWF upper chart/850 temps through the next 4 days.

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When you get into a wet pattern like we did last April and soils become saturated, there is a feedback that kicks in between soil and atmosphere. The wet ground, moistens the lower atmosphere and so this favours lower pressure and an tendency for for more rain. Drier than normal soils can lead to higher pressure and there is more of a tendency for sunshine and little rain. Once we had the rains we did back in April, this lead to a wetter than normal summer and with the amount of water lying in Britain’s ground, the wet pattern was likely to continue with more cloudcover favoured due to the amount of water vapor the ground was releasing into the atmosphere. What we’re seeing now is the first real dry spell in 11 months and it finally appears we have broken that soggy cycle which once started is hard to breakdown. This spell is allowing not only top soils but deep soils to now dry out but this pattern needs to continue if it’s going to provide us with a more settled spring and summer.

Given the near neutral ENSO currently with neither an El Nino or La Nina, there is a likelhood that a La Nina will develop this summer due to the cold PDO. This would favour a drier summer and likely winter in 2013-14. A nice dry spring would likely lead to a drier, sunnier and warmer summer this year. If we enter summer on the backside of a dry spring, this means the warming sun has less evaporation to do. To explain further, as the sun becomes stronger, any moisture in the soil gets drawn out and released to the atmosphere and as some of the sun’s rays go into evaporating this moisture released from the ground, while the rest of the sun’s solar rays go into warming the ground and then air. Less moisture in the ground means more energy from the sun goes directly into warming the ground and lower atmosphere. In other words we should see more sunshine and warmer temperatures.

Last March was exceptionally warm for the time of year but this occured because we had back to back dry years and the NAO was favouring positive, so there was a tendency for higher than normal pressure over those very dry soils. This pattern lead to record-breaking warmth over Scotland 3 days in a row and warmer than normal conditions throughout the UK. At the close of a near summer-like March, it was like the atmosphere flicked a switch and the flood gates opened just as a hosepipe ban was declared for a large portion of England.

This March won’t be nearly as warm, in fact it may end up colder than average but what I am optimistic about is the fact we should be entering a drier than normal spell which could be taking us right through spring (April, May).

While a drier spring is possible this does not mean we don’t get wet days. It also doesn’t mean we have a warmer than normal spring either. In fact, given the persistency and bias towards a negative NAO, we may in fact have a cooler than normal spring. A lot of things need to be ironed out yet.

So, what about our weather through this weekend and next week?

The ECMWF continues to suggest yet another cold blast is on the way with possibly more snow showers and temperatures which struggle to reach freezing late this weekend into early next week. The core of the trough and arctic air dives into central and eastern Europe but it appears we still get much colder once again, so make the most of the ‘milder days’.

Here’s the ECMWF for late week, this weekend into early next week.

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Despite the shift to mild and then likely back to cold late weekend into next week, the moral is the continuation of dry weather. Yes, we will see some rain/snow showers but from here on in, what falls or doesn’t fall from the sky is important. Ultimately if we get a drier than normal spring, this summer may well be drier and therefore warmer. The seeds to our summer are being planted now. The last truely warm and drier than normal summer throughout the UK and Ireland was 2006 believe it or not and it seems for several years now I have been saying, we’re long overdue a decent summer. With the warm AMO, unfortunately we have a battle there as those warmer than normal waters tend to lead to wetter summers. Howevere, like everything else, there are breaks within these multiyear cycles just like we saw with last winter.

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