WEST EUROPE: Cool, Showery -NAO Driven Pattern Likely To Continue Into June

Written by Mark Vogan on May 16, 2015 in Rest of Europe, Spring 2015, United Kingdom & Ireland with 0 Comments

Our current pattern remains very zonal (westerly) with a distinct north-south divide with cool, blustery showers over Northern Ireland/Scotland whiles always drier, brighter and warmer the further south you go. However change is on the way. That change will be in the form of ‘direction in which our Atlantic lows come in from’. Unfortunately we’re not going to loose the unsettled but ultimately add to the cool of this Atlantic pattern.

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There’s cross model agreement that heights rise in a big way over the North Atlantic next week and so a trough and lows within, will come into the UK and Ireland from a more NNW rather than WSW direction. This is a colder outlook.

While it’s no washout, what will be worth noting is that because we’re heading towards summer’s first month and the sun is strong and high in the sky, surface warming is greater than before and by drawing in colder northerly air masses over top of warmth (when the sun shines) underneath, you have the recipe for very heavy showers, thundery downpours which can cause flooding or worst case, flash flooding.

Next week sees at least two lows drop into the UK from Iceland and these systems will pull down polar air with it. Therefore as well as your typical wind and rain with a chance of mountain snows, we’re likely to see the development of intense cells which can produce downpours, hailstorms and thunder and lightning. Lapse rates will be large and therefore the speed at which air travels vertically, speeds up, forcing the more intense shower.

GFS surface through the upcoming 7 day period.

Credit: AccuWeather Pro

Sub-freezing temps of 0 to -5C at 850mb or 5,000ft vs +9-15C down at the surface, you’ve enhanced instability and ‘lift’ within the atmosphere. This is the perfect setup for fair weather cumulus to rapidly build vertically into the -15 to -25C region of the upper atmosphere, giving way to localised torrential downpours.

gfs---europe-72-A-850hgt

By night, under clear skies and if winds drop off, expect frost in rural areas.

Summer Likely To Open Cool, Showery Based On Current Model Projections

Models are in strong agreement about a -NAO pattern developing and holding into at least June’s first week and with positive to the north/northwest and negative overhead, you remain under a ‘frequent heavy shower risk’ as well as system wind and rain typically associated with low pressure fronts.

nao_sprd2