Headed For Record Dry April Following One of Coldest Opening 16 Days?

Written by on April 18, 2021 in Rest of Europe, United Kingdom & Ireland with 0 Comments

Despite some movement back and forth, on the whole High pressure has been holding firm over the UK in recent weeks bringing not just drier but colder than normal conditions. This can likely be attributed to the La Nina and possibly other factors including MJO as well as solar state. The mean position of the high to-date has produced one of the coldest 1st halves to an April in many years, if not on record.

Credit: Michael Ventrice

UK mean average temperatures through April 18.

Credit: Reading University

UK mean temperature anomaly through April 17.

Credit: Reading University

Despite a milder 2nd half to April, the month is destined to end well below average.

While chill has probably been the big story this month, the dryness is likely to take to the stage as we ease on the cold and the lack of rainfall continues.

Most of the UK has seen 20% or less rainfall this month with some spots including Leuchers, Fife and central London not recording anything since March.

The question is, when will this pattern break down? It won’t through the rest of this month if the models are correct and so this could turn out one of, if not thee driest April on record for the UK.

Total rainfall for the UK and Ireland through April 16.

Credit: University of Reading

Here’s the percentage of normal precipitation through April 16 for the UK and Ireland.

Credit: University of Reading

GFS ensemble precipitation anomaly

week 1

Credit: Tropical Tidbits

Day 7-13

Credit: Tropical Tidbits

Cfsv2 weekly precipitation anomaly

week 1

Credit: Tropical Tidbits

week 2 turns slightly wetter in the SW.

Credit: Tropical Tidbits

It’s pretty well understood, prolonged periods of little rain are often followed by considerably wetter periods. Take 2012, following a very dry February and record dry and warm March, the month of April turned out the wettest on record and the summer was a washout I believe down to the combination of warm waters surrounding the UK and development of an El Nino. The 2012 season probably goes down as my biggest summer forecast fail.

Dry springs can be followed by wet summers and then again, dry soils and cool (not warm) surrounding waters can lead to higher than normal mid and upper level high pressure and eventually hot weather into early summer.

Check out the current SSTA’s around the UK.

Credit: Tropical Tidbits

So, to conclude. The drier than normal theme looks to persist and may push this April to record levels or close. The question is what next?

Models indicate a neutral ENSO signal by mid summer.

Do we get a dry to wet flip?

May could remain dry but also cool with potential for slightly -AO/NAO. The CFSv2 sees Greenland blocking and subtle trough near to the UK.

I will be sharing my initial summer thoughts in the coming days on Youtube so be sure to watch out for this. I also should be releasing a summer forecast in early May.

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