Aerosols from Mount Pinatubo's eruption on 12th June 1991, spread
around the globe in the troposphere and allegedly blocked the sun,
cooling the tropics. It is further alleged that this reduces the north
to south temperature difference that helps to shift the Arctic
Oscillation, keeping frigid air in the north during the winter,
resulting in mild conditions over much of eastern North America.

But, when Alaska's Mount Katmai erupted on June 6, 1912, most of the
aerosols remained well to the north, where they were not heated as
much. In turn, the lower stratosphere did not warm greatly, so there
was little influence on the Arctic Oscillation.

http://pubs.giss.nasa.gov/abstracts/...manRobock.html


1912

4 Jan 13:29 The year started with a wet spell and continued. Possibly
with a deep low over Britain.
11 Jan 07:43 Then there was a very unsettled spell with many fronts.

19 Jan 11:10 With this spell a series of lows would have given way to
anticyclonic weather.
27 Jan 08:51 Which in turn would have turned thundery.

2 Feb 23:58 Low overcast and mist or drizzle with this spell. [1]
10 Feb 00:50 Might have turned a lot wetter with some wind.
18 Feb 05:44 Before turning back to overcast with many fronts. [1]

25 Feb 19:26 This spell is similar to the one for 4th Jan, being 6
hours different.

3 Mar 10:42 And this is similar to the spell for the 11th Jan, being 3
hours different. [2]
10 Mar 19:55 So, another dry spell.

18 Mar 22:08 Wet.
26 Mar 03:02 Thundery.
1 Apr 22:04 Wet as with the 18th Mar.
9 Apr 15:24 And this is a super wet spell is it? Half past thundery.
17 Apr 11:40 Unsettled. And I really don't like to guess.
24 Apr 08:47 Again unsettled.
1 May 10:19 Unsettled.
9 May 09:56 Wet.
I'm sure that if this volcano had been monitored, there would have
been records of activity there.
16 May 22:13 More wet spells. And look how closely they repeat.
23 May 14:11 Wet.

30 May 23:29 This is a fine spell in normal circumstances but I think
the harmonic from all those wet spells would have stymied it. Also
of course it is somewhat off in the Atlantic.
8 Jun 02:35 And this is another. Two days late to help, though.

1991

7 Jan 18:36 Why not start off with an awkward one? That's what
volcanoes thrive on.
15 Jan 23:50 Cold and overcast.
23 Jan 14:22 Awkward one.
30 Jan 06:10 Dull and overcast.

6 Feb 13:52 Fine.
14 Feb 17:32 Fine if a little off.
21 Feb 22:58 Fine.

Is anyone besides me beginning to get the picture?

28 Feb 18:25 A repeat. Now there's a surprise.
8 Mar 10:32 This is a wet, one isn't it?

16 Mar 08:11 Fine.

23 Mar 06:03 Dull and overcast.

30 Mar 07:17 Fine going on unstable.

7 Apr 06:45 Wet and windy.
14 Apr 19:38 Awkward. Here it comes.
21 Apr 12:39 Yep. This is when it started.
28 Apr 20:58 Thundery.
7 May 00:46 Wet and windy.
14 May 04:36 Oof, I hate these!
20 May 19:46 And these.
28 May 11:37 Awkward.

5 Jun 15:30 Half past thundery.
12 Jun 12:06 So when I get a series of ones I don't like
forecasting. I shall forecast major volcanic activity.
19 Jun 04:19 More awkward ones.

I think that following recent developments, the 4 o'clock spells are no
longer going to be awkward ones.