The UK, Ireland and indeed much of Europe is currently enjoying a mild air mass with highs well into the 15-20C range widely. Temps have climbed to 22C this afternoon in the Scottish Highlands, making for the warmest day of 2014 UK-wide. However, significant change looms for the second half of this week.

[s2If current_user_can(access_s2member_level1)]

Here’s a glance at the ECMWF surface for today. After a wet, windy weekend, note that heights are fairly strong and we have a slack air flow.

850mb temps indicate relatively mild air at 5,000ft.

Today’s mild temps

Another mild day tomorrow.

Notice in the GFS jet stream chart that the UK and Ireland remain stuck in a slack upper air flow within a high pressure zone dominating much of our continent between two branches of the jet. The northern branch is keeping the arctic air well to our north while the southern branch is supressing sub-tropical air well to the south, we’re stuck in the no-man’s land between. While mild to warm, we’re not in either air mass through the first half of the week but the wind barbs veer northerly into the second half as the northern branch drops to our south.

jet stream at 36 hrs off GFS.

72 hrs

Note by 90 hrs or 0z Friday, the northern branch merges with the southern branch and thus the cold air crashes south.

Check out the MUCH colder air at 5,000ft by this time.

Much colder air arrives Thursday as a cold high builds down from the north. Frost chances greatly increase by night.

By Friday the mild air is push into the far south while Scotland, Northern England and Northern Ireland is stuck in the 5-9C range.

During Friday, the cold air will cover the UK and Ireland. Thanks to high pressure, we should experience widespread clear skies with light winds. This sets the stage for a significant rural ground frost Friday night into Saturday. Lows will almost certainly drop to 0C away from towns and cities across a broad area of the UK. Some favoured cold spots may push -6C! Could challenge some of the colder readings seen during the past winter believe it or not…

As fast as this chill arrives, it gets replaces by that sub-tropical air mass to our south and we see the southern branch lift to our north. Yep, the northern branch drops south, then the southern branch lifts to our north! The ups and downs of our spring pattern.

Check out the jet stream chart by 156 hrs. The chill is kicked east, replaced by milder air of Azores origin as the southern branch lifts north!

Check out the GFS surface chart at 156 hrs.

168 hrs

If you haven’t already, be sure to read yesterday’s Europe and El Nino posts which looks at the longer term pattern with some interesting theory you won’t find anywhere else!

[/s2If][s2If current_user_cannot(access_s2member_level1)][magicactionbox id=”18716″][/s2If]