Dr. Eddy Graham's Hebridean Weather Blog

by Dr. Eddy Graham

Merry Christmas from Eddy!

Posted by Dr. Eddy Graham on 19 December 2014, 10:00 AM

Wishing everyone a peaceful Christmas and festive season 2014/15

 

Scotland in the Snow (Christmas 2010) - NASA/MODIS/GSFC

Sincerely, Eddie

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Weather Outlook for Christmas 2014

Posted by Dr. Eddy Graham on 19 December 2014, 9:46 AM

Staying unsettled, with frequent heavy rain, gales and wintry showers (but thankfully no significant storms in sight just yet), but an increasing chance of a crisper 'Northerly' spell of weather, with frost, ice and perhaps some snow as we head towards Christmas and beyond...

Fun in the Snow

Posted by Dr. Eddy Graham on 15 December 2014, 8:56 AM

Thick fluffy snow came tumbling down over Stornoway on Saturday, bringing delight to the young and not so young...  Seo aon no dha photos..

 

 
 

 

 

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Focus now on ice and snow

Posted by Dr. Eddy Graham on 11 December 2014, 4:27 PM

Latest: There's a risk of another fall of snow for tomorrow (Monday 15th Dec) morning

The focus on the weather has now shifted from thunderstorms & gales to the risk of ice and snow. 

Ice is likely tonight (Thursday night) with some accumulation of hail or snow, especially away from the coasts and on hills. Tomorrow (Friday), there is a chance of more substantial snow as the day matures (with early coastal rain quickly turning to snow).

The Calanais Standing Stones in Winter Snow (The Graham Family)

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"Weatherbomb" Sparks!

Posted by Dr. Eddy Graham on 10 December 2014, 10:51 PM

"WeatherBomb" Facts and Sparks!

  • The number of lightning strike hits over the north of Scotland was the highest since 5th December 2013
  • But the total number of thunderstorms within 24hrs is highest I can recall (see map below) - over five individual storms affected Stornoway within 24hrs
  • Max wind gusts were: South Uist: 82mph, Bealach na Ba: 105mph; Stornoway: 72mph

Lightning Strikes on 10th December (courtesy Icelandic Met Service)

Why are we getting some many thunderstorms? It's probably the enhanced sea-surface temperatures around the north of Scotland, says Eddy (see orange colours) - NASA ESRL image

A tree came down across the path to Lews Castle College during the storm (Eddie Graham)

The NASA satellite image for today, 10th December (Scotland is under there somewhere!)

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Back to Winter Reality: 933hPa Atlantic Low Tuesday 9th Dec

Posted by Dr. Eddy Graham on 06 December 2014, 4:16 PM

Latest Update (Tuesday 9/12/2014, 5pm):


Update (Monday 8/12/2014, 9am): It's not looking quite as bad as feared now, with the low pressure 'up' to 942hPa. but we'll still get  a severe gale both tomorrow (Tues) and again Wed, with gusts approaching 70mph - these are still hazardous winds, so please be careful. More wintry squalls are likely too, with thunder and lightning again, large hail and sleet/wet snow (the photo below shows the large hailstones in Stornoway on Sunday 7th Dec)

 


Original post of Sat 5th Dec follows:

Usually a deep low with an intensity of 930hPa or less occurs only about once per decade in the North Atlantic - but last winter we had many such instances..

And so it now seems like this winter doesn't want to be left behind as a poor second-best... because a seriously deep low of 933hPa is forecast to develop south of Iceland at 12h Tue 9th December, passing north of the Hebrides at 12h Wed with a slightly diminished intensity of ~940hPa (see charts below).

 


Met Office Chart for 12h Tues 9th Dec (above)

 


Met Office Chart for 12h Wed 10th Dec (above)

At this stage, the strongest winds within the sting jet (hurricane force) appear to be heading for the Faroes and the Rockall Trough on Tues eve, with somewhat reduced winds of Storm Force 10 (perhaps violent storm 11 north of the Butt of Lewis) expected for the Hebrides 12h Wed. But this is still a dangerous storm and anything could happen yet... so I strongly advise everyone to consult the updated weather forecasts in the coming few days.

The astronomical high tide on Tues/Wed in Stornoway is 4.80 to 4.90m - so there could be a risk of storm surge flooding, with a correspondingly huge swell out to sea on the west coast.

Meanwhile, we'll have some (very) temporary snow tomorrow (Sunday) - the deep cold Arctic air is already making its way south of Iceland as I type (see below) - the thunderstorm anvils are turning anti-cyclonically (plenty lightning sferics have already been reported), indicating powerful squalls, snow, hail, thunder, lightning and very deep cold air - so we may even get a visit from 'nan Seachd Siantan' again...

Updates shall follow..

Eddy, Stornoway, Sat 6th Dec 2014

 

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Hail squalls, sleet & snow flurries likely Fri/Sun: Risk storms next week

Posted by Dr. Eddy Graham on 03 December 2014, 9:56 AM

Hail squalls and snow flurries are likely to affect Stornoway and the Isles this coming Friday, thawing Saturday, only to return again Sunday. Current indications are that any snow is unlikely to lie for long.

On top of this, following the massive influx of cold Canadian air that is causing the snow, severe gales, or even storms, are likely early next week. As of yet, it is uncertain exactly where and when the storms may hit, but we should know in better detail by this weekend.

Eddie, Stornoway, 3 December 2014

Update Thurs 4/12/14: Latest model output suggests hail/sleet during Friday, freezing overnight on roads; thaw Saturday; more substantial snow showers (away from onshore coasts) on Sunday, lying temporarily. Gales early next week.

Friday update (6pm 5/12/14): Still the same as above. A nasty swell on west coast too by Monday.

As the oceans part for Moses, so the clouds part for Lewis...

Posted by Dr. Eddy Graham on 01 December 2014, 9:29 PM

The following spectacular NASA MODIS satellite image, taken on the morning of Sunday 30 November, shows the clouds parting from around the Isle of Lewis (Scotland).

 

Eddy, Stornoway, 30 Nov 2014

This has happened because the airflow is perturbed by the mountains of Harris and Uig (to the south and southwest of the island). The reason the mountains and land are able to do this is because the cloud layer was very low and shallow (thinner than the height of the mountains), and also because  the airflow was very mild and stable (with no significant decrease in air temperature with height).

 

A telephoto zoom shot (above, taken through a 10 X 50 binocular eyepiece, from a distance of approximately 50km) shows this cloud being forced to ascend the Clisham mountain (2622 feet, 799 metres) and then descending on the near-side in a strange "waterfall" fashion. This unusual meteorological situation is known as the "foehn" (after the name of a warm wind in the Alps).

 

Meanwhile the satellite image from two days earlier (above, 28 November) shows a crystal clear sky over the whole of NW Scotland, the Minches and the Hebrides. The only cloud of any note are a few blobs of cumulus over the NW Highlands in Sutherland, over Beinn Mhor & Hecla in South Uist, and two blobs over South Harris. What looks like snow in the glens of the central Highlands is actually the highly reflective top of fog filling the valleys. Look closely, you can see these 'fingers' of fog filling the glens in a near-perfect (but inverted) reflection of topography!

Eddie, Stornoway, 1 December 2014.

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The Halcyon days

Posted by Dr. Eddy Graham on 30 November 2014, 11:26 PM

The Halcyon days are meant to be a period of 7 fine days, occurring during early winter, when (in Greek mythology) Aeolus restrained his winds in order to allow for the kingfishers (Halcyons) to lay their eggs. 

Well, it has been a bit more than 7 days already... indeed, what beautiful weather we have been having for the past 2-3 weeks across the Hebrides and NW Scotland - it seems as though winter has been delayed or indefinitely postponed... the grass is still growing and air temperatures have been more akin with October...

  

More details shall be forthcoming in the next issue of the Stornoway Gazette, but here are a few nice photographs from the Stornoway Castle Grounds over the past 3-4 days.

A great view of Stornoway from Gallow's Hill on 28 November: 

 

And a mirror-still Stornoway Harbour on 28 November: 

 

Finally a nice reflection in the still water of the duck pond! 

 

Eddy, Stornoway, 30 Nov 2014

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Doing as the Romans do...

Posted by Dr. Eddy Graham on 27 November 2014, 10:23 PM

Vene, vidi... amavit (I came, I saw, I fell in love...)

  

  

And well, no visit to Rome is complete without an audience with Papa Francesco himself (and the Italian football team)...

 

Or indeed a wee spin in a Ferrari...

  

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Rome by night

Posted by Dr. Eddy Graham on 27 November 2014, 10:02 PM

All roads lead to Rome - and at night they led me for a wondrous week across this truly magnificent city, fueled by a nearly endless supply of Italian espresso and gelato (Italian ice cream).

  

  

  

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Fine Easterly weather to last till Friday/Sat

Posted by Dr. Eddy Graham on 19 November 2014, 1:05 PM

As expected, we've been having some lovely dry, fine and exceptionally mild easterly weather lately. Current indications indicate that it will last until Friday night/Saturday (21st/22nd November), before more seasonal heavy rain, showers and south-westerly winds return over the weekend and into next week. It will turn temporarily much colder for a time Sat/Sun too (with sleet on the hills), but will quickly turn mild again next week.

Eddie, Stornoway, 18 Nov 2014

 

East and South-Easterly Winds to Bring Good Drying to Hebrides

Posted by Dr. Eddy Graham on 09 November 2014, 10:36 PM

Yes, as indicated in my last post of more than 1 week ago - high pressure is indeed building to the north of Scotland, meaning the resulting east and south-east winds are likely to bring good drying conditions and fine skies for several days across the Hebrides and Northwest Highlands.

It won't be rain-free all the time, but there'll certainly be a lot less rain than we've had during the past 3-4 weeks. So some good news indeed!

Eddie, Stornoway, 9 Nov 2014

Here comes the rain again...

Posted by Dr. Eddy Graham on 02 November 2014, 12:49 PM

Despite October & November being two of the wettest months of the year normally, it has been exceptionally wet recently - indeed it has been near-record wet.

A quick look at the weather stats for Stornoway town show that 150mm (6 inches) of rain fell in final 15 days of the October. As the graph shows below, 15-day running totals of 150+mm have only occurred three times in the past 15 years, so yes, we are having a particularly unusual wet spell at the moment, equivalent to an event of about once in every 5 years.

Another 18.1mm fell during the day on Saturday 1st November - probably increasing the above odds yet further... but there are tentative signs the weather may finally quieten down by late next week as high pressure builds from the east - thank heavens!

Eddy, Stornoway, 2 Nov 2014

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Mega "Seeder-Feeder" Rain Event

Posted by Dr. Eddy Graham on 26 October 2014, 8:39 PM

If you've been staying anywhere near the west or north-west of Scotland over the past week or so, you'll know just how relentless the rain has been... but there's an even bigger threat of flooding tomorrow (Mon 27 Oct) for the mountains of the West Highlands (from Oban north through Fort William to Ullapool, including Harris and Skye).

 

Eddy ain't expecting record rainfall amounts, but the Met Office has wisely issued an amber alert for heavy 'orographic' rainfall across the region. Orographic means 'of mountains', and whilst we all appreciate that mountains are wetter places than surrounding lowlands - what's happening tomorrow makes them very much wetter places. It's called the "seeder-feeder" mechanism, whereby "average"-sized raindrops falling from a high frontal cloud-band  fall down "seeding" low-level clouds lying over the mountain summits. Whilst passing through these dense, water-rich clouds, they rapidly "feed" upon that cloud's droplets, making the resulting raindrops much bigger - yielding a greater quantity of rain at the surface (Hill, Browning and Bader 1981). It was the same mechanism that led to the Cockermouth flood in Cumbria in November 2009, after intense orographic rainfall over the Lake District of England (Sibley, 2010).

How much rain is gonna fall?

See map above (courtesy GFS met model) - the current low resolution model cumulative rainfall amounts suggest 100-150mm of rain is expected at least, for most locations across the West Highlands, but I expect some places will receive up to 250mm in 48 hours (on top of what's already fallen). These are not records amounts, but are still very significant falls of rain, making the potential for flooding and disruption. The burns and rivers are likely to become dangerous, raging torrents.

Some Weather Stats for Past Few Days (Stornoway):

  • 85mm (3.35in) of rain has fallen over the past 9 days in Stornoway town
  • 73mm (2.95in) of rain fell in 36hrs at Loch Glascarnoch (nr Ullapool) from 6am Saturday to 6pm Sunday
  • 55mm (2.16in) of rain has fallen at Lusa, Skye (nr Broadford) in the past 24hrs
  • The maximum wind gust of 67mph at Stornoway on Saturday night was stronger than that during ex-hurricane Gonzalo of last week!

Stay Safe!

Eddy, Stornoway, 26/10/2014, 9pm 

References:

Hill, F. F., Browning, K. A., & Bader, M. J. (1981). Radar and raingauge observations of orographic rain over south Wales. Quarterly Journal of the Royal Meteorological Society107(453), 643-670.

Sibley, A. (2010). Analysis of extreme rainfall and flooding in Cumbria 18–20 November 2009. Weather65(11), 287-292.

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Hurricane Hysteria - 'Godzilla' Panic V Gonzalo Hype

Posted by Dr. Eddy Graham on 19 October 2014, 2:28 PM

There's a kind of 'anticipated panic' setting in across Scotland today, the sort that you might expect in a 'Godzilla' movie - all because the remains of ex-hurricane Gonzalo are due to pass over us tonight and tomorrow.

Here's a sat-pic of Gonzalo (courtesy Environment Canada) over the Atlantic at -65W, 48 hours ago (note the eye at his centre):

Well - here's Eddy's viewpoint (an update from previous post of last week, below):

As expected, ex-hurricane Gonzalo will pass right over Scotland tomorrow night (Monday) and into Tuesday.There won't be a hurricane - but there'll be heavy rain and blustery winds, continuing the unsettled theme to the weather of the past 48 hours. On Tuesday a strong gale force wind (force 9, perhaps 10) will belt in from the northwest across the Hebrides - with a slight risk remaining of locally stronger gusts and squalls, as the passage of ex-hurricanes are generally not very well forecast. So still very unpleasant weather (but not a hurricane). Max wind gusts will be around 60-70mph.

Eddy, Stornoway, 19/10/2014, 2:30pm

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It's Hurricane Season!

Posted by Dr. Eddy Graham on 13 October 2014, 10:09 PM

In case you weren't aware - it's North Atlantic hurricane season - which runs from July to November each year. On average, the Caribbean and Atlantic Ocean actually get fewer tropical cyclones per year than the far-east, and this year has proved no exception with some extraordinarily severe typhoons forming in the far-east in past weeks.

As for Bonny Scotland - we've already had the remains of "Big Bertha"  in August (bringing floods and damage), and the chance of another ex-hurricane (or a deep depression formed from the remains of an earlier hurricane) brushing our shores remain high for the coming weeks... presently there's a hint that Hurricane Gonzalo (not Godzilla!) will head north-east across the North Atlantic around 21st-23rd of the coming month... so keep posted!

(n.b. No updates from Eddy till next week)

Eddy, Stornoway, 13/10/2014

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Plumes of sediment from recent storm in Eastern Scotland

Posted by Dr. Eddy Graham on 09 October 2014, 11:27 AM

The NASA MODIS satellite sensor picked up very clearly the large plumes of sediment along the Eastern coast of Scotland yesterday (8th October 2014), following a powerful storm in the region the day before.

The plume from Cowie Water (a river) exiting Stonehaven (top of image) is most noticable. Given the correct conditions, river water (being fresh) will float on top of saline sea water (being more dense).

Eddie, Stornoway, 9/10/2014

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"Big Blow" Tonight (Thurs 2nd Oct)

Posted by Dr. Eddy Graham on 02 October 2014, 3:06 PM

N.B. Remember that you can find all my latest weather updates on Twitter @eddy_weather with hashtag #uhiweather

3pm Thurs: Winds are already a southerly gale force 8 at Stornoway Airport, and they'll increase further this evening and tonight, reaching gusts well over 60mph by late evening. Heavy rain is likely too.

Here's the sat-pic for Thursday morning - showing a classic baroclinic wave typical of severe depressions and cold front separation.

Slight damage is possible, particularly around Stornoway as the trees are still in leaf (i.e. heavier) and the southerly wind will funnel up the Minch considerably.

Friday 9am: Max gusts as follows: Stornoway Severe Gale Force 9 at 8pm, gusting 62mph. Total rainfall: 15.1mm.

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So you think I'm Irish, do you? (Eddy's Celto-Iranian-Kazakhstani DNA Surprise)

Posted by Dr. Eddy Graham on 29 September 2014, 9:14 PM

'Yes' to Indian Summer Heatwave!

Posted by Dr. Eddy Graham on 12 September 2014, 10:59 AM

The political climate of Scotland is not the only thing that's heating up to fever pitch at the moment... for the fine Indian Summer weather that we've been having recently is set to continue for much of the coming week in the run-up to the historic Scottish Independence Referendum on 18th September. Indeed,  it could even intensify into a possible mini-heatwave...

It's said Emperor Constantine saw a cross in the sky on the eve of a famous battle (which he won) and it was instrumental in his conversion to Christianity... well let's see what I photographed in the sky..

The September air temperature record for Stornoway is +25.0degC. At the moment, this record looks unlikely to be breached but it could well be approached as temperatures exceed 20degC across the NW Highlands and the Isles this weekend and early next week.

Enjoy!

Eddie, Stornoway, 12 Sep 2014

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Midge Plague enters Tesco in Stornoway

Posted by Dr. Eddy Graham on 05 September 2014, 9:55 AM

If you haven't noticed the incredible number of midges that has been plaguing the Highlands & Islands for the past month or more... well you can't have been living at all! - This year's midge numbers have been confirmed as record breaking, with as many as 900,000 midges caught in a single trap in on day in Wester Ross last month.

For the past week or more, the wee blighters have even entered Tesco supermarket in Stornoway, and proceeded to devour customers as well as the checkout assistants - I personally had to escape the Fruit n' Veg aisle and head towards the cooler midge-free dairy aisle in order to escape being bitten!

The reason for the vampire invasion: A very mild, wet winter with no hard frosts, followed by a wet, humid and warm summer.

Stop scratching!

Eddie, Stornoway, 5 Sep 2014

Wettest August in over 20 years

Posted by Dr. Eddy Graham on 01 September 2014, 9:55 PM

With a total of 185.1mm (7.31in) of rain, it has been the wettest August in the Stornoway region since 1992, some twenty-two years ago.

But somewhat in compensation,  the final week of sunshine at the end of the month meant that it was no less sunny than normal, and the cold spell of weather mid-month was equally offset by a warm start and finish.

Eddy, Stornoway, 1 Sep 2014.

 

"Indian Summer" weather for a few days

Posted by Dr. Eddy Graham on 25 August 2014, 9:35 AM

There's at least three days of fine fresh "Indian summer" weather ahead - though it'll be cool overnight with heavy early autumn dews, the days should be gloriously fine with long sunny spells and warm temperatures up into the mid-teens degC.

Interestingly, yesterday (Sunday 24th August) saw glorious skies across most of the Isles and the westside of Lewis - though the sun was spoiled by local cloud and showers over central Harris and east Lewis (including Stornoway) as the satellite image (below) shows. But with the wind shifting into the east from today onwards, this shouldn't happen again - enjoy!.

Eddie, Stornoway, Mon 25/8/2014, 09h30

 
 
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August Summer Chill

Posted by Dr. Eddy Graham on 20 August 2014, 10:11 AM

We are not experiencing record low air temperatures for August, but there has certainly been a very autumnal chill in the air over recent days.

The high temp on August 18th in Stornoway was a mere +12.3degC. Although more akin to mid-October than mid-August, this is still some 3degC above the record daytime low for August in Stornoway which is +9.4degC recorded on 26th August 1919. There have been at least 120 occasions in the past 145 years of days in August in Stornoway when the max temp failed to reach above 12.3degC  (equivalent to a chance of about 1 in 34).

Wrap up and stay warm!

Eddie, Stornoway, 20.08.2014

 

 
 

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