Posted by Dr. Eddy Graham on 25 September 2015, 5:43 PM
The good news is that high pressure is building again over this coming weekend (26-27 Sep), bringing settled and drier weather. It's not certain yet how much sunshine we'll get (indeed it will be dull and breezy with drizzle at times around the coasts and hills during early Saturday and again on Sunday), but hopefully from Monday onwards there will be some nice spells of warm, late Indian summer weather - temperatures could reach 18degC on the Isles, and over 20degC inland over the Highlandse.g. Inverness region. It will be breezy at times too, especially in the Minch with a strong southerly breeze at times, but no gales.
Posted by Dr. Eddy Graham on 20 September 2015, 10:33 PM
I've been down in sunny Dundee for the past 2 days, taking part in the BBC Tour 'Make it Digital' tour - in an attempt to try and improve digital literacy among school-children. I was helping to man the BBC Weather and Royal Meteorological Society's tent, where we had many interactive weather attractions for young and old.
Weather and the meteorological sciences make use of vast amounts of digital/computing resources, hence their inclusion in the tour.
Here's our set-up location, in City Square Dundee, right beside the beautiful Caird Hall (below):
The weather tent was just on the left (below):
View across City Square:
Oh boy, what's this? A Dalek! (Dr. Who has a tent across the square! - see below):
Yours truly in his BBC Weather T-shirt
Now, back to the weather -some lovely 'eyebrow' wave crests of sc. lenticularis over Inverness
Posted by Dr. Eddy Graham on 08 September 2015, 9:14 PM
At long last it seems the weather has settled down, bringing us an "Indian Summer" - this term is often used to describe a spell of fine weather late in the year, usually anytime from late August to early November.
NASA MODIS Satellite Image of a sunny Minch, Lewis, Harris and NW Highlands, but a dull and misty Inverness (9 Sep)
The NASA Terra satellite sensor passed over Scotland this morning (8 Sep) and revealed the Highlands and Isles emerging from a persistent (but gradually evaporating) deck of cloud and fog. This is what it saw - Can you pick out each glen and loch in the West Highlands?
Posted by Dr. Eddy Graham on 29 August 2015, 10:25 PM
Recently I visited the longest remaining glacier in Europe, the 'Aletsch' (Switzerland), during the peak of the intense continental heatwave of summer 2015. Presently, the glacier is 23km long, but like the vast majority of glaciers worldwide, the lower reaches of the Aletsch are melting quickly due to global warming. Intense summer heatwaves such as 2015 are highly detrimental to the survival of glaciers (during the 2003 heatwave, the Aletsch was observed to be receding at 1 metre per day, and about 50m per year on average over recent years) See below for a range of geomorphological photographs.
This first pair of photographs shows the extent of the glacier tongue in 2008 (left) and its considerable retreat/dimunition by 2015 (right):
Here's a fuller view of the glacier, looking towards the Gross Wannenhorn, with its five mini corrie glaciers (background):
And next, as we descend to the glacier - newly exposed terrain below the tree-line reveals a glaciologist's paradise - we are walking on one of the old medial moraines here:
Looking back upslope across glacial smoothed rock, and some trees have established themselves in places:
Now, we're almost at glacier level (about 1900-2000 metres above sea level), and a small fen / bog area has developed in one of residual troughs / rock basins left behind by the glacier:
Recently exposed terrain on the south side of the glacier: Considerable rockfalls are adding detritus to the top surface of the glacier.
That's me (below) in the French foreign legion hat (a most useful protection against the searing mid-summer sunshine). We are at the edge of the glacier, where an ice-cave has formed due to melting water. It is lovely to drink!
Danny (age 9) surveys f the glacier snout.
by Dr. Eddy Graham, Stornoway, Scotland, August 2015
Posted by Dr. Eddy Graham on 23 August 2015, 10:44 PM
Today (Sunday 23rd August) was the warmest day of year so far. Highest temperatures recorded were as follows:
Stornoway Airport: 21.4C
Stornoway town 22.5C
Harris Quidnish: 22.0C
South Uist Range: 23.3C
Askernish, South Uist 24.7C
Lusa bridge, Isle of Skye: 25.5C
Amazingly and due to an 'inverted warm sector', it was much colder to the south of Scotland, with Dublin Casement in Ireland recording a high of only 14.1C today - see the upside down synoptic weather chart!
Posted by Dr. Eddy Graham on 18 August 2015, 12:52 PM
While north-west Europe and Scotland remained damp and frigid during much of the summer, most of the nearby continent saw an intense heatwave during July and early August - on a parallel (or even more intense) than the heatwaves of summer 2003 and July 2006.
Posted by Dr. Eddy Graham on 16 July 2015, 3:08 PM
There was a magnificent display of noctilucent clouds, coupled with a weak green aurora glow, last night (15/16th July 2015) in Stornoway and across the Hebrides. Noctilucent clouds are the highest known clouds, forming at a height of over 80km in the mesosphere. Because of their great height, they remain brightly lit by the Sun during the northern hemisphere summer. The clouds are very thin and tenous have a characteristic 'electric blue' colour. According to NASA, the water vapour required for their formation probably originates in meteorites.
Posted by Dr. Eddy Graham on 15 July 2015, 11:34 PM
Thursday:Good! A nice dry day again for the most part, with nice spells of sunshine breaking through by afternoon, but east breeze picking up by eve taking the edge off the temps. Late into Thurs night, heavy rain breaking out and fresh winds.
Friday:A spell of heavy rain will come through during the early hours I'm afraid, together with strong easterly winds. Clearing up then for a while by mid-morning/midday - but more showers breaking up by afternoon, risk heavy with thunder! - so wellies are a must!
Saturday: More rain and showers, but lighter in nature and clearing - drizzle, and feeling much colder as a fresh northerly wind picks up. Some brightness too though so not all bad!
Sunday & Next week: More of the same, more rain - sorry!
Posted by Dr. Eddy Graham on 30 June 2015, 8:59 PM
It is official, May and June 2015 together will go down in the met history books as two of the most awful months (of their namesakes) ever recorded in Stornoway.
Overall, the May+June 2015 period was the 2nd wettest on record since 1873 in Stornoway, the 4th dullest (lack of sunshine) and 10th coolest since 1900. Put altogether, these are by far the worst weather statistics for May & June combined since records began in Stornoway in the mid 1850s.
Graphically, we view these statistics are follows:
Temperature: But for a milder final five days of June, it would have been the 4th coldest June on record. Instead, it works out to be the coldest since 1987, and the 10th coolest May-June on record in Stornoway:
Sunshine-wise: Need I say anymore: There's an horrendous vitamin-D deficiency for all concerned (4th dullest on record) [BTW, the values for 2004 are missing due to a changeover of instrument at Stornoway Airport]:
And rainfall - mein Gottlieb Daimler! 2nd wettest on record, and if it pours again tonight (30th June), we'll break the record (as June rainfall-month officially ends at 09h00 on 1st July).
Posted by Dr. Eddy Graham on 26 June 2015, 10:32 AM
On the evening of 23 June, I was very fortunate to be offered a lift to visit the El Teide Volcano and the Izaña Astronomical Observatory (the largest in the northern hemisphere)
El Teide Volcano, Spain's highest mountain (3719m). We are above the trade-wind inversion cloud layer, which sloshes back-and-forth in the valley below, just like waves on the beach - see more here: https://vimeo.com/23205323
The obligatory selfie (I'm sure that I must win the "try to get the UHI logo as-far-as-possible" competition, as I have done nearly equivalent photos at Sutherland (South Africa) and Paranal de Atacama (Chile).
And here's the summit of Izaña mountain (2400m), with its plethora of telescopes
And again, the obligatory selfie & UHI 'lets-win-this logo' competition!
The approach by road to El Teide Volcano
Note the fossil red and yellow soils between the lava flows
The Sun Photometer at Izaña is one of the longest serving instruments in place at the location - it has run non-stop since the 1970s.
View to the clouds and Gran Canaria island far, far below.
At night, I got to see the new Laser Guide Star in action (it helps the focusing of the telescopes by creating an artificial star [made by a powerful laser beam which excites sodium atoms in the upper atmosphere]) - wow, it's like alien star wars!
Posted by Dr. Eddy Graham on 26 June 2015, 10:09 AM
What a beauty the island of Tenerife is - I am here for a week, attending a conference on astronomy and presenting a review talk on the influences of meteorology and climatology on astronomical observation.
Let me show you round; firstly let's visit Santa Cruz de la Tenerife (where I am staying):
Iglesia de la Concepcion
Plaza del España
Hang on a sec -What this? The Scottish Saltire flying proudly from a government building in Santa Cruz? (can you work out the riddle)
Santa Cruz harbour
Walking the narrow calle (streets) of Santa Cruz
Red Flamanco trees are everywhere, adding their beautiful colour to the already azure skies.
Lovely Spanish architecture dating from the colonial times.
General O'Donnell - come on, what Irish maverick came to Tenerife?!? (Actually he was a brutal military leader who later became Prime Minister of Spain,)
The Recova (Open Market) in Santa Cruz is a experience to remember
Now let's take a tour of the north of the island: Firstly, to La Laguna, where the conference is taking place:
The location of the Guajara Campus of the University of La Laguna is second-to-none.
A selfie, overlooking the valley of La Laguna
View from the Guajara campus of the University
Order of priority on the trams - bikes over (fit and able) people, yay!
And grassy green tram tracks - we could learn a few environmental lessons from the Canary Islanders!
Posted by Dr. Eddy Graham on 24 June 2015, 10:04 PM
On the night of the 13/14th of June, the air temperature at Lews Castle ('The Meadows' at Alt nam Brog) dropped to below freezing, with -0.2C recorded at 04h00. This represents only the 2nd time in the history of record-keeping in Stornoway that an air frost (an air temperature below freezing 0.0 degC) has been measured during the month of June. The only previous occasion was on 10th June 1888 (127 years ago) when an air temperature of -0.6degC wasalso recorded near Lews Castle.
Overall, climatologically speaking, it is no exaggeration to say that the month has been an 'ice-bath'! It looks like being the coldest since at least 1987, and possibly even 1927 - at least the 5th coldest on record. Coupled with a sequence of consecutive very poor weather over the past 6 months, we are frankly at at the rock-bottom of climatological anomalies.
If it doesn't warm-up in Stornoway over the next 5 days, this is where June 2015's average air temperature will lie in met history:
It's all due to the very cold North Atlantic ocean at present, and persistent onshore westerly winds - sea temperatures change only very slowly, typically many months. The past month's sea surface temperature anomaly can be seen here (reproduced below): http://www.esrl.noaa.gov/psd/map/clim/sst.shtml (blue = cold).
The month has yet to finish - but with only 88hrs of bright sunshine recorded to date, Stornoway may also be heading for the one of dullest Junes on record since 1929 (worryingly, 5 of worst 7 have been recorded in the past 25yrs).
Posted by Dr. Eddy Graham on 27 May 2015, 11:56 AM
Eddy (2 June 2015): I can now confirm that May 2015 was the 7th wettest May on recordin Stornoway (in 143 years of record keeping), at least the 29th coolest but probably in the top ten coolest (due to a change of observing site since 1942), and the 20th dullest (out of 86 years). So all-in-all, awful!
Although a few days remain until the month's close (at the time of writing), we can safely say that it has been one of worst Mays in 20 years across the Isles, according to the weather statistics.
Temperature-wise, it will come as no surprise to learn that with an average temperature of hardly 8degC, it will be the coolest May since 1996 (nineteen years ago). On the 1st of the month, a low temperature of -4.3C was measured at Lews Castle Meadows, Stornoway, almost equalling the May low-record for Stornoway of -4.4degC recorded in 1938.
The daytimes were particularly cold, with a brisk, cool westerly wind on most days. The graphic below shows that we haven't seen as cool a May during the daytime since at least 1979 (the two coolest in the series are 1979 and 1923).
Sunshine-wise, it was also a very dull month - some places in Scotland have seen hardly more than half the average sunshine for the month. At Stornoway Airport, it is within the bottom 10% of dull Mays ever measured at the Airport.
It was also another wet month (although May 2011 was wetter) - about 150-200% of average May rainfall has fallen across most regions of Scotland this month.
So you think May's weather can't get any worse, can you?
Well, sorry, have I got news for you... a frigid blast of cold Canadian air (direct from the Davis Strait between western Greenland and Labrador) is expected to impact the Highlands and Islands Saturday-Monday. Expect frequent rain/hail showers with blustery squalls from Saturday afternoon onwards - some sleet is even possible at times, with snow on the highest hills.
n.b. See 2nd image below - sea surface temperatures in the North Atlantic are considerably below normal at present. The negative anomalies are some of the lowest on the globe with respect to the rest of the world at present.
A rare hook echo was apparent in the Lewis radar scan of this morning's torrential rain (see below). This is BAD NEWS meteorologically speaking, and rather unusual for a maritime location of British Isles in May.
Hook echoes (the curvilinear feature on the rainfall radar image, over Lewis and Harris) indicate rotation in a storm clouds, yielding possible severe thunderstorms, hail, flooding rains and possibly even tornadoes (when the hook is well developed).
A very bright infra-red image (see next image) also indicates powerful convection to the tropopause.
Spring and summer, oh summer, have you deserted us?
Posted by Dr. Eddy Graham on 10 May 2015, 11:01 PM
With another soaking near-inch of rainfall (20mm) in Stornoway on Sunday 10 May 2015, many folk are rightly beginning to ask "Where is Spring?" (let alone summer!).
There's no definite answer to this, other than saying no prolonged respite from either the unseasonal cold, nor recurrent rain, appears likely over the coming week. Certainly sea temperatures in the North Atlantic ocean are considerably below normal at present(see map below) - but there is no straightforward link between weather conditions in the Hebrides and the above.
So we will have to wait and see what summer brings - let's just hope it won't be another 1816, aka 'The Year Without a Summer'.
N.B. From NASA: Two nice satellite images of line convection over the Isles, Fri & Sat 8/9 May 2015:
And the current sea temperature anomalies - blue means cold!
There's still no sign of a lengthy pause or calming-down of the weather situation, with respect to the latest St. Kilda swim attempt.
Presently, a 36-hr window that was previously forecast from early Friday 8th - Sat 9th May now seems to be closing-in slightly (with a N/NE swell of 1-2 metres remaining). However, a new window starting around 00h Sunday 10th May may be opening (see NOAA WWIII chart below for Sun 00h - green means a mean wave height of 5ft or greater)
Posted by Dr. Eddy Graham on 01 May 2015, 10:19 PM
With a min temp of -1.3degC this morning in Stornoway town, it was the 2nd coldest night of the 'winter' period 2014-2015. At Lews Castle meadows (Alt nam Brog, a frost hollow site), the min temp was an incredible -4.3C, just short of the lowest on record for May in Stornoway, which is -4.4C set in 1938.
Meanwhile, Tulloch Bridge in Lochaber on the mainland went down to -5.6C.
Today (daytime), despite strong sunshine all day, the air temperature reached only +8.2C in Stornoway town (a value more akin to March).
Posted by Dr. Eddy Graham on 28 April 2015, 10:16 PM
Update to Outlook:
The good news is that it's going to become much milder by the end of the coming weekend. The lovely spring sunshine will continue Friday and Saturday too, as breezes swing into the east.
A period of strong cold easterly winds is likely early on and during the day of Sunday. Some rain is likely too (snow on hills), but hopefully showery in nature. The good news is that it will become much, much warmer by Monday, though with the increased risk of heavy, blustery showers breaking out.
In closer detail, a slack flow will prevail till Friday or so, followed by a strengthening easterly flow later. There is disagreement between the met models on how soon the east wind picks up, moves in our direction, and then how soon it dissipates.
As for the St. Kilda swim hopefuls, the NOAA Wavewatch-3 model has swells less than 1m (deep blue) in the inner Minches for midday Friday, increasing by midday Saturday (see images, Fri 12h, Sat 12h).
Sat 12h (below):
Thereafter, larger swells are likely stretching into next week, as active lows swing up from the southwest.
Sea temperatures are also running 1 to 2degC below normal in mid-Atlantic at present (see below):
Posted by Dr. Eddy Graham on 24 April 2015, 11:46 PM
On the night of the Stornoway Hurricane (8-9 January 2015), I inadvertently left a camera running for 5 minutes on a window-sill in my home at the height of the storm. No visual imagery was recorded (the screen was simply black due to the pitch during the storm) but I realised recently that the audio file might prove valuable.
You can hear part of it at http://youtu.be/8iCHNxmC944 (with the visual backdrop of a few photos - but the sound itself is actually best listened to without the imagery).
Bear in mind that this recording was made using a small camera indoors, located some distance from double-glazed windows.
Posted by Dr. Eddy Graham on 24 April 2015, 2:25 PM
Yes, it's true - winter is about to make a brief return during this coming weekend, with raw northerly breezes bringing flurries of sleet, hail and snow at times (especially Sunday), and hard frosts by night - beware all gardeners and plant growers!