Dr. Eddy Graham's Hebridean Weather Blog

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NASA Terra satellite spies snow extent over Scotland

NASA's Terra satellite flew over Scotland this morning at a height of 705km and captured the following two images:

Capture.PNG.20 Capture2.PNG.7

There's a near complete snow cover over the country but it's all very ephemeral I'm afraid - it'll disappear as quickly as it came!

(False colours: Left: red=snow; Right: cyan=snow).

@eddy_weather, 14 January 2017

Arctic blueskies and snow: View from Stornoway Ranol today

This was the view from Stornoway Ranol hill today, at the top of the Stornoway Golf course: There was about 3-5cm of crisp, frozen snow lying:

2017-01-13 14.18.00.jpg Capture.PNG.19

Capture2.PNG.6

@eddy_weather, 13 January 2017.

First snow of the winter in Stornoway

After the record mild December, at times it felt like it was never going to come... but finally the first snow of the winter is lying across Stornoway tonight - especially on the town's hilly Golf course, where snow enthusiasts (young and old) were out doing some night-time sledging this evening...

2017-01-12 19.13.19.jpg

A few facts on the current cold snap:

  • #thundersnow was recorded in Stornoway three times in the past 36 hours: 5h30 and 16h30 Wednesday, and 8h50 Thursday
  • About 3-5cm of snow is currently lying on undisturbed ground, with deeper drifts in places (due to the strong wind)
  • The air temperature has been ABOVE zero throughout the event (typically +1.5degC), but due to a lowering dewpoint, the snow began to lie properly from midday Thursday due to the ice-bulb effect (yesterday the high winds meant the latent heat transfer was too large and prevented settling of the snow)
  • Most of the snow is actually graupel - soft rimed hailstones!

@eddy_weather, Stornoway, 12 Jan 2017

 

Eddy on #Thundersnow

#Thundersnow is the new weather buzzword that's recently come across the pond from Amerikay...

lightning-552038_960_720.jpg

Listen to Eddie explaining more on BBC Radio Scotland yesterday here: http://www.bbc.co.uk/programmes/b086lh6q at 1hr 26mins 36 secs (or 10:26a.m.).

@eddy_weather

The Weather of 2016 in Stornoway: At a Glance

tn_P1021338.JPG

I've completed a climatological analyses of the weather in Stornoway during the year of 2016.  Rather than write a tedious monologue, I'be summarised all relevant monthly values in a Table, which is presented below.

Overall the year was mild with the mean temperature about +0.5degC above normal (but not as warm as it was in 2014).  Rainfall was close to average (i.e. much drier than in 2015, which was a record wet year) and there was near average sunshine too. The number of air frosts was below normal.

Station:

Stornoway Town 04004

                       

Status:

Semi-Homogenised

                     

Year

2016

                       

Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

 Year

Mean Max

7.1

6.7

9.2

9.6

12.9

15.6

16.1

16.8

15.7

13.3

8.6

9.9

11.79

Mean Min

2.8

0.9

3.8

3.4

6.8

10.2

10.8

10.5

10.2

6.9

2.9

4.9

6.18

Mean (degC)

5.0

3.8

6.5

6.5

9.9

12.9

13.5

13.7

13.0

10.1

5.8

7.4

8.98

Highest Max

12.9

10.7

13.5

12.5

19.7

20.0

22.0

22.2

19.2

17.4

13.3

13.1

22.2

Highest Min

10.8

4.9

8.9

6.9

9.8

13.5

14.9

13.9

13.4

12.8

11.2

9.6

14.9

Lowest Max

2.5

3.6

4.6

5.8

9.7

11.9

14.3

14.2

12.2

9.6

3.9

3.9

2.5

Lowest Min

-1.9

-2.3

-2.1

-2.7

2.8

7.2

6.2

4.2

6.2

0.8

-2.5

-1.7

-2.7

Air frosts

7

8

4

3

0

0

0

0

0

0

6

2

30

Grass Frosts

16

23

19

12

1

0

0

0

0

9

17

10

107

Lowest Grass

-6.4

-5.5

-6.4

-5.4

-1.4

4.0

3.1

3.0

1.9

-4.1

-6.7

-6.7

-6.7

Precip (mm)

157.5

154.7

92.6

53.4

62.9

80.0

143.5

86.8

139.0

38.9

114.6

133.0

1257

Wettest

18.8

24.0

27.7

5.8

11.0

12.5

26.1

20.2

20.6

10.8

23.2

14.3

27.7

Raindays (>=0.2mm)

24

26

22

24

12

17

30

16

23

12

25

27

258

Wetdays (>=1.0mm)

18

23

14

14

10

14

23

12

21

10

21

23

203

Hail

7

12

4

7

2

0

0

0

0

0

6

6

44

Thunder

3

1

0

0

1

1

0

1

2

0

0

2

11

Snowfall

10

16

6

7

0

0

0

0

0

0

5

5

49

Snow Lying

7

2

1

1

0

0

0

0

0

0

0

0

11

Max snow depth (cm)

2

2

2

2

0

0

0

0

0

0

0

0

2

Cloud percent

0.8188

0.7349

0.6956

0.7318

0.7042

0.8073

0.9346

0.6821

0.7243

0.5559

0.6170

0.7917

0.73

 

@eddy_weather, Stornoway, 2 Jan 2017

Record Warm December in Stornoway

With one day of the month yet remaining, December 2016 looks like being a record-breaking mild month in Stornoway.

Eddy reports that the average air temperature for this December will clock in at approximately +7.7°C, almost a full 3°C above normal – or about half a degree warmer than the long-term average temperature for April!

Such a degree of warmth is ‘highly unusual’, and follows very high global air temperatures during both 2015 and 2016. This December will also rank as the warmest of any winter month (December, January or February) for the full period of the Met Office archives, which stretch back over 150 years in Stornoway (one of the longest such series in Scotland).

The following chart places the warmth within the long-term context of all winter months from 1873-2016:

Dec2016-wrm.png

The weather is set to change over the weekend, however, as a short cold snap ushers in wintry flurries and chilly north wind for the New Year.

@eddy_weather, Stornoway, 30 December 2016

#stormConor was Cat 1 Hurricane over Faroes on Christmas Day

You may have missed him, but #stormConor was a fighting wee monster as he passed through Thorshavn (Faroes) on Christmas Day.

 output_xajflx_cropped.gif

The 4pm SYNOP for Thorshavn WMO station 06011 read as follows:

Air Temp: 4.0C Dewpoint: 1.4C Pressure: 966.6hPa Wind dir: NW Mean speed: 72kts (Hurricane Force 12), gusting 102kts (117mph)

and again at 6pm:

Wind gust: 102kts (117mph)

That's several mph stronger than the Stornoway 03026 Hurricane of January 2015. Thorshavn 06011 also recorded 4 consecutive days from 23rd-26th of wind gusts exceeding 95mph (and 3 consecutive days of over 100mph).

The satellite animation above (courtesy of sat24, images copyright METEOSAT)  shows that Conor was a classic Shapiro-Keyser low, with a probable #stingjet being the reason for the exceptional wind speeds (Shapiro-Keyser 1990). Further evidence for the stratospheric intrusion of very dry air (usually found in the region of a tropopause lowering with a #stingjet) can be seen in the following METEOSAT 6.7µm water vapour channel image for 12h (below).  A prominent dark area (dry intrusion) lies directly east of the cloud head tip, and also west of the main frontal boundary:

meteosat-msg_wv062_overlay-vector-overlay.jpg

This dry air arrived in Stornoway during the evening of Christmas Day. A dewpoint of -6.4C was recorded at 18h with a relative humidity of only 45% (due to the 'ice-bulb' effect, the ground was freezing despite an ambient air temperature of +5.5C). The NAVGEM global met model also indicated that widespread tropopause lowering was taking place near #StormConor (red blotches on following chart):

nvg10.tpause.006.europe2.gif

@eddy_weather, Stornoway, 29/12/2016

Reference:

Shapiro, M.A. and Keyser, D.A., 1990. Fronts, jet streams, and the tropopause. US Department of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Wave Propagation Laboratory.

 

#StormBarbara at T+24

Update by Eddy, Friday 11am: The #stingjet of #stormBarbara now looks like staying offshore. Hence maximum expected wind gusts can be reduced from the extreme values given below. So staying wild, but not crazy (thankfully!). See my latest posts on Twitter at: https://twitter.com/eddy_weather

---BEGIN--- (original post)

Please note this is Eddy's final prognostic on #StormBarbara. I will however, be posting analyses and diagnoses during and post-event on Twitter (should power supplies permit so).

Here's how I view the development of #StormBarbara:

Barbara will be a very powerful storm, with maximum wind gusts within the #stingjet* of probably over 100mph. However, there is disagreement still between the models over the exact track of the jet. The final track of this jet will prove crucial regarding the impact of Barbara.

Currently the Global Forecast System (GFS) mean has the #stingjet remaining out to sea, to the north-west beyond St. Kilda, Butt of Lewis, Flannan Isles and Sulisker (see charts below). In this run, gusts of 70-80kts affect N and W Lewis, with up to 100kts (120mph) within the #stingjet, well offshore:

gustkt_033.jpg

However, the all met model ensemble mean (the best estimate from all met models at the moment) indicates that GFS has slow wind bias for the region 58.0degN, -4.0degW (see next chart):

ens_58.0_-4.0_384_kt_06.png

In contrast the COSMO European model (run at highest possible resolution) has a quite frightening prediction with windspeeds in excess of 115mph (180km/h) blasting into west Harris and westside Lewis at 17-18h (see next chart). If realised, this would make it almost as strong as the 'Stornoway Hurricane' of 8-9 Jan 2015.

COSMO-Fri23Dec2016-17 h.PNG

Conclusion: With such disagreement, analyses of real-time satellite imagery will prove key as to the position and area of the sting jet / cold jet which will cause the most violent winds, as well as indicating the Langrangian (relative) speed of the system itself.

p.s. Late addition: I notice the US NAVGEM model is now pulling Barbara further NW again, in line with GFS.

Likely temporal Sequence of Events (very rough guide ± 2-3hrs):

6am: Frontal trough of storm reaches Barra, torrential rain and wind gusts reach 60-70mph.

8am: Same reaches Stornoway

9am-12 noon: Winds increase to gusts of 75mph

~Lunchtime: As frontal trough clears, a temporary 'lull' back to 60-70mph gusts

2pm-8pm: The main hooley, with the most violent winds moving northwest across the Hebrides from Barra to Lewis. Highest wind speeds are likely to last 2-3 hours in duration (depends on speed of system herself). Max gusts are as indicated above (between 80-115mph). If the #stingjet stays well offshore, this stage will be reduced in severity.

10pm-midnight: Worst hopefully over.

The Christmas Day Storm (perhaps #StormConor): It looks like it will also be a strong storm, but current model runs suggest a track further still to the NW. Let's deal with him only after ##StormBarbara!

22 Dec 2016, @eddy_weather, Stornoway

  * Please note that I am using the term 'sting jet' for both sting jets and cold jets (or cold conveyor belts). This is not strictly correct meteorologically speaking - but since the public are more familiar with the term sting jet, I am using this term alone to avoid confusion.

---END---

 

Thundersnow in Stornoway on the Winter Solstice

There was snow with thunder and lightning in Stornoway today (21 December 2016). It was captured by the Stornoway Lews Castle College radar (see below):

C0N2CfLXEAA-dMu.jpg

The occurred just after 16h: See the bright red colour (top right image) & pink (bottom left), as well as large vertical velocity Doppler shifts (shades, bottom right). These are indicative of large hail, large snowflakes and considerable turbulence respectively, leading to the exchange of electrical charge. You can learn more about what the colours mean here: https://uhi-mahara.co.uk/view/view.php?id=24843

Known as 'thundersnow', it is a common misconception that thunderstorms require heat and warm weather for their development. This is a false premise: What thunderstorms really need is atmospheric instability, which is a frequent occurrence in deep cold polar airflows over warm ocean surfaces, such as happens fairly often in NW Scotland during wintertime.

@eddy_weather, Stornoway, 21 Dec 2016

 

Storm #Barbara to be first major storm of winter

#StormBarbara - here she comes Friday (23 December) at 90mph+. Another storm is possible late Christmas Day. The devil will be in the detail, so please keep alert to Met Office warnings, as the exact track of each storm (yet to be pinned precisely) will determine their severity on land. Don't be fooled by any temporary lulls - it may be just the eye of the storm passing over (though I think both eyes will stay out to sea on these x 2 occasions). I shall be tweeting updates on Twitter (as long as the power holds): https://twitter.com/eddy_weather

C0HED8ZWEAAD7QH.jpg

Official Met Office Warning:
http://www.metoffice.gov.uk/public/weather/warnings/#?regionName=he&from=rss&sn=07EA8E4A-143C-8CC5-83B2-1B54CA34F60A_3_HE&utm_source=dlvr.it&utm_medium=twitter&tab=warnings&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1482451200

@eddy_weather, Stornoway, 20 Dec 2016

Big Change in Weather For Xmas

Well you've heard it all already - I'm pretty confident that the big change in Atlantic weather that I mentioned last week is now imminent (caused initially by the collapse of an intense cold air dome over Canada last week).

Expect severe gales in the run-up to Christmas, with (brief) snow Wednesday night/Thursday; otherwise torrential rain, violent hail squalls, storm force gusts, thunder and lightning too. Keep alert too to closer short-term warnings (from reputable providers of course e.g. The Met Office) - some of the individual storms could be very potent, and blow up (and out) within less than 24hrs.

'Tis the season...

Podcast from the Met Office today:

@eddy_weather, Stornoway, 19 Dec 2016

Warmest December Fortnight on Record in Stornoway

The past fortnight (5th-18th December 2016) has been the warmest fortnight on record in December in Stornoway, confirms @eddy_weather. Digitised meteorological records in the town go back to 1873, one of the longest such series in Scotland. The mean daily high temperature has been +11.9C, and mean daily average has been +8.9C.

This statistic will be easier to understand when presented in the following graph. The last time it was nearly so mild in December was in 1971 (with a mean daily high of +10.9C and mean daily average of +8.4C in the two weeks up to 20th December), but it has never been as mild as present at any time in recorded history.

December warmth

This news exposes the absurd "post-truth" forecasts of last month (e.g. "Four months of Snow Ahead") in the true light and fact of day.

@eddy_weather, Stornoway, 18 Dec 2016

Eddy's Outlook for Christmas week: Very stormy with frequent severe gales, torrential rain and hail squalls - with snow likely over the winter solstice (Wed night 21st/ Thurs 22nd Dec) - but it will be the most unpleasant type of snow (dull, raw and wet rather than deep, crisp and even!). Possibly even stormier for Christmas Eve and Day, watch out! 

October mildness in December: But major weather changes in Atlantic this week!

The past week has been astonishingly mild in Stornoway: The average daily high has been +11.8C, with a daily low of +7.1C; these values are more akin with early-to-mid October than December!

However, major changes are afoot in Northern Hemispheric atmosphere over the next few days. In stark contrast with the winter so far, a dome of extremely cold air (with a 1000-500hPa thickness of less than 480dam) will collapse over eastern Canada, surging out over Labrador and Newfoundland during mid-week. This will create an intense thermal (baroclinic) gradient, likely leading to super-powerful storms in the western North Atlantic (933hPa is forecast near Newfy on Thurs). It's not certain yet whether such energy will transfer east to Scotland - but it's worth keeping on eye on my blog and Twitter in the coming days just in case (NAVGEM met model T+84 and T+126 charts below).

11dec2016_nvg10.thk.084.atlantic.gif

11dec2016_nvg10.thk.126.atlantic.gif

@eddy_weather, Stornoway, 11 Dec 2016

Am faic sinn sneachda aig àm na Nollaig?

Saoil am faic sin sneachda aig àm na Nollaig am bliadhna?

Bha mi a 'bruidhinn ri an fìor-àlainn Cathy Bhàn seachdainn seo chaidh! Seo an clàradh:

Cathy.PNG

Faodaidh tu èisteachd ris a 'clàradh anseo: http://www.bbc.co.uk/programmes/b08305s3#play 

@eddy_weather, Steornabhagh, 7mh dhen Dùbhlachd 2016

Post-Truth Meteorology

Met Office Predicts White Christmas for All Scottish Cities

Four Months of Snow and Bitter Winter Ahead

Do either of the headlines above seem familiar? Did you read them in any of the Scottish newspapers recently? 

Both statements actually come from leading Scottish daily newspapers printed during the last fortnight. The unfortunate reality is that both are lies - such predictions are no more accurate than the average horoscope or crystal ball gaze. But surely these are 'White Lies'  (lies told without any intentional harm)?

Alas, this is not the case either. They are cases of 'Post-Truth Meteorology' - a term I recently coined on the television programme Sunday Politics Scotland, based on the new word of the year 2016: Post-Truth. The meteorological aspect works like this:

Deliberately false media reports about the weather (such as above) are becoming increasingly commonplace.  These 'forecasts' are not made by scientists, but are instead created by journalists with a political agenda and other attention-seekers. However, the publishing newspapers falsely attribute them to scientists and meteorologists (e.g. The Met Office), so as to increase public doubt and confusion over weather and climate change. This can have serious political ramifications, as the public are then less likely to support mitigation measures against climate change (such as renewable energy), or take precautions in the advent of severe weather.

You can view Eddie talking on the BBC here:

@eddy_weather, Stornoway, Scotland (December 2016)

Climate Stats for Stornoway: November 2016

Following the glorious October, November 2016 proved to another sunny and dry month, relative to normal. The clear skies meant nights were cold, however, with an unusual sequence of 7 frosty (and icy) nights-in-a-row from the 18th to 24th.

Capture4.PNG.1

Statistics from Stornoway town weather station:

https://www.wunderground.com/personal-weather-station/dashboard?ID=ISTORNOW2

Mean Max: 8.6degC (Highest: 13.3degC on 14th, Lowest: 3.9degC on 17th)

Mean Min: 2.9degC (Highest: 11.2degC on 14th, Lowest: -2.5degC on 18th)

Lowest grass: -6.7degC on 18th

Precip: 114.6mm (Wettest day: 23.2mm on 8th)

Thunder: 0; Hail: 6; Snow Falling: 5; Snow Lying: 0; Grass Frosts: 17; Air Frosts: 6; Raindays: 25; Wetdays: 21; Cloud Cover: 61.7%.

Long-Term Trends (based on Met Office records from the town and airport, since 1873):

It was the sunniest November in nearly 20 years, with a total of 57.0hrs. Overall this made it the 11th sunniest in 87 years (see chart below). In terms of rainfall it was the 31st driest out of 144 years, so equivalent to a 1-in-4 or 1-in-5 event. Temperature-wise, it was slightly cooler than normal due to the clear skies, and the number of air frosts was well above average. 5 air frosts were recorded at the Airport with 6 in the town (the long-term average is only 1.8).

 Nov-Sunshine.png

@eddy_weather, Stornoway, 4 December 2016

 

 

 

Maritime Arctic Airmass Views from Stornoway

Spectacular maritime arctic skies during the recent cold snap in Stornoway (by Eddy):

weather image

Varied hues of Cumulus mediocris radiatus, with congestus.

Translation: Small heaped clouds, wider than taller, in a line; with a few taller than wider versions.

weather image

The remains of a cumulonimbus anvil, but the cumulonimbus tower is no more! Cirrus spissatus virga cumulonimbogenitus.

Translation: Horse's hair (ice) cloud, thick with falling snowflake streaks (virga), formed earlier by a cumulonimbus shower cloud.

weather image

Arcus, ahead of an approaching cumulonimbus squall.

Translation: A threatening arched line of cloud racing out from a thunderstorm.

weather image

Cumulonimbus incus capillatus (white cloud in background).

Translation: A raining large heap of a cloud, possibly with thunder, with a flat-top shaped like an anvil, producing ice-cloud like horse's hair.

weather image

A powerful single cumulus congestus thermal (white) rises under the shadow of an enormous cumulonimbus incus anvil (dark left).

Translation: A heap of cloud, taller than wider.

weather image

And a severe hoar frost (air temperature -4.6degC) at 08h00 on 18 November, Stornoway Golf course. The grass min temperature was -6.7degC in Stornoway town.

@eddy_weather, Stornoway, November 2016.

November chill? A diagnosis and prognosis by Dr. Eddy

There's been some speculation that the coming winter will be a cold and snowy one. Certainly the past fortnight (up to 20 November) has been rather chilly across Scotland, with early severe frosts and heavy snow falling on the mountains. So what's the prognosis for the rest of the winter? 

Every winter brings snow, especially in Scotland! And humans have enjoyed speculating (not just on the weather) since time immemorial. And after two or three mild and stormy winters on the trot, it's not that difficult to predict a change in our weather fortunes!

At the same time, however, recent advances in atmospheric science mean that there are some guides to the general state of the hemispheric* weather pattern for perhaps a few to several weeks' ahead in time.

Let's start by looking at today's global weather pattern (courtesy of the University of Maine - see map below). This shows the current air temperature anomaly. There's an intense pink swath across Siberia and central Asia where it is record cold at the moment - but it is equally hot over most of the Arctic Ocean (where there has been unprecedented reduction in Arctic sea ice). A wee smidgen of blue over Scotland and Ireland confirms our current cold snap, but overall the British Isles occupy only a tiny part of the global picture. 

weather image

Today's air temperature pattern arises due to aforementioned 'Arctic amplification' due to sea-ice loss (Serreze et al. 2006), and very unusual stratospheric dynamics. Let's now consider the latter i.e. the stratosphere, which is the region of the atmosphere between 15 and 40km in altitude above our heads.

Stratospheric conditions are sometimes known to 'teleconnect' down to the surface, over the course of several weeks following an event such as a Sudden Stratospheric Warming (Mitchell et al. 2013). Today, NOAA's 50 millbar (~20km) air temperature plot shows clear signs of a polar vortex breakdown (see plot below). In 'normal' circumstances, there should be a circumpolar 'low' surrounded by a 'high'; instead we have a shift of the 'low' south to mid-Atlantic with a 'high' in the Bering strait - current forecasts indicate that this pattern is unlikely to change for at least the next 2 weeks.

weather image

Finally, winter storms in the North Atlantic region take their energy from the contrast in sea surface temperature between the Poles and the Tropics. They also gain energy from the condensation of water vapour evaporated from over the oceans. Here's the current sea surface temperature anomaly from NOAA Earth System Research Laboratory. There remains a cold pool ('the big blue blob'; Josey et al. 2016) in the middle of the North Atlantic, surrounded by warmer water on all sides, much the same as it was in 2015 (when a very stormy and record wet winter ensued). 

weather image

So all-in-all, a dodgy stratosphere, a very dodgy Arctic, and a stubborn big blue blob!

Conclusion: I'd say that we'll continue the cool and variable start to the winter (remainder of November, early December), but there always the chance of severe storms and gales returning, especially during the second half of winter (if the Arctic and stratosphere return to more 'normal' conditions).

@eddy_weather, Stornoway, 20 November 2016

* The Rossby waves, usually at wavenumber 6 or 7

References:

Josey, S., Grist, J., Duchez, A., Frajka-Williams, E., Hirschi, J., Marsh, R. and Sinha, B., 2016, April. Causes and Consequences of Exceptional North Atlantic Heat Loss in Recent Winters. In EGU General Assembly Conference Abstracts (Vol. 18, p. 4562).

Mitchell, D.M., Gray, L.J., Anstey, J., Baldwin, M.P. and Charlton-Perez, A.J., 2013. The influence of stratospheric vortex displacements and splits on surface climate. Journal of Climate, 26(8), pp.2668-2682.

Serreze, M.C. and Francis, J.A., 2006. The Arctic amplification debate. Climatic Change, 76(3-4), pp.241-264.

 

Big Minch 'Danglers' and Sunny Uist and Barra 'on the Lea'

Meso (and micro) scale meteorological effects gradually more become enhanced (i.e. less dominated by the synoptic airflow) when skies clear (allowing greater radiation fluxes) and winds slacken (reducing convective and advective heat transfer).

Today (Sunday 6 Nov 2016), we can see this in action across the British Isles: A strong northerly airflow has led to mesoscale convergence (meeting of air) over the Irish Sea, and a long narrow line of powerful convection (known as 'Pembrokeshire Dangler') has developed, extending more than 200km downstream into coastal Pembrokeshire and Cornwall. This is a common feature of the weather during northerly outbreaks (Mayes et al. 2013; Norris et al. 2013).

sat pic

Meanwhile, closer to home in NW Scotland, we can see a (reduced) similar effect in the Big Minch between NW Scotland and the Outer Hebrides. Showers have been funnelling down between the Harris and Skye hills all day, whilst inland Lewis has stayed dry. Further south, the Uists and Barra have been bathed in glorious sunshine, maintaining a 'clear slot' of sunny skies all the way to Donegal in Ireland ('Sunny Uist and Barra on the Lea').

sat pic

@eddy_weather, Stornoway, 6 Nov 2016

Images courtesy #NASA MODIS channels 367.

References: 

Mayes, J., 2013. Regional weather and climates of the British Isles–Part 5: Wales. Weather, 68(9), pp.227-232.

Norris, J., Vaughan, G. and Schultz, D.M., 2013. Snowbands over the English Channel and Irish Sea during cold‐air outbreaks. Quarterly Journal of the Royal Meteorological Society, 139(676), pp.1747-1761.

 

Best October in decades!

It's been the best October across NW Scotland and the Isles for decades.  Based on the long-term records for Stornoway, with a precipitation total of only 36.0mm (1.42in) it was the 2nd driest in 144 years of record keeping for the Isles (1873-2016) and the 4th sunniest since 1929 (87 years). See the graphs below by @eddy_weather.

graph

graph

Further information can be seen in a recent Met Office press release: http://www.metoffice.gov.uk/news/releases/2016/end-of-october-2016-stats

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Various views of NW Highlands and Islands during October fine spell

Below please find a few spectacular NASA Terra satellite images of NW Highlands and Islands, Scotland, during the recent fine spell of weather:

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NASA Terra channels 3, 6 and 7: Ice clouds show up as orange or pink, water as black and land as emerald green (11 October)

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NASA Terra channels 7, 2 and 1: Ice clouds show up as cyan blue, water clouds as white, open water as black and land as lush green (10 October).

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NASA Terra Visible and Infra-Red channels: As close to as we see them with our own eyes (if we were in space) - 5 October.

@eddy_weather, Stornoway, October 2016

Eddy goes East with Etihad

The United Arab Emirates (UAE) of the Middle East present one of the strangest of juxtapositions of climate, land and people on Earth today. Despite having one of the hottest, driest and most inhospitable climates on Earth (air temperatures regularly surpass +50degC during the summer season), the region today boasts two of the most extraordinarily wealthy, ultra-modern and glittering cities found on Earth: Dubai and Abu Dhabi.

Eddy-Weather recently had the good fortune to visit the latter of these two cities (Abu Dhabi). He also spent some time observing the unique weather systems of the region.

The primary reason why the weather is so hot in the UAE is because it lies on the eastern fringe of the world's greatest sandy desert, the Rub' Al Khali of the Arabian Peninsula. At a latitude of only 24degN, the Sun remains very strong all year-round (and is directly overhead in the zenith during the summer season). The UAE also lies exactlly under the influence of the global descending arm of the Hadley Cell circulation, the Earth's most powerful air circulation system. Furthermore, lying beside one of warmest seas on the planet (the Persian Gulf), the weather can get extremely humid as ocean temperatures frequently reach well above +30degC. Here are some photos:

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View across Abu Dhabi to the southwest. Note the hazy blue skies - the restriction in visibility is due to a combination of fine desert dust and anthropogenic aerosols, some of which are likely to be hygroscopic at high relative humidity.

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The Abu Dhabi National Oil Company (ADNOC) headquarters and Etihad towers (location of the Fast and Furious Tom Cruise Hollywood movie), in downtown Abu Dhabi.

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Eddie on the Marina seafront.

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2nd wonder of the modern world: The Sheikh Zayed Grand Mosque

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The Dusit Thani hotel (515ft high): "A little town in heaven"

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The thermodynamic upper air plot (tephigram) shows conditions typically of the region, with two separate inversions at 920mb and 600mb above Abu Dhabi, with a surface air temperature of +33degC. Very dry air lies above both inversions.

@eddy_weather, October 2016

 

Intense Narrow Rain Band passes through Stornoway 27/9/2016

Intense bursts of rain caused by a 'Narrow Rain Band' (NRB) were captured by the Lews Castle Micro-Rain Radar in Stornoway this morning, Tues 27 Sep 2016. Having only been recognised as unique and distinct meteorological features in their own right in the past decade or so, these bands of rain comprise of heavy downpours only a few kilometres wide, but can stretch for tens to hundreds of kilometres in length. They may cause considerable disruption, as they are sudden, squally events, and are often accompanied by severe wind gusts and torrential bursts of rain, lasting all for a few minutes.

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As this morning's Stornoway radar images show (above), NRBs are shallow features, originating from turbulence in warm low-level clouds. Note that there are at least 2 x separate NRBs in the plot above - the final one at 0745UTC (08h45 local time) was hardly more than 1,000m deep.

@eddy_weather, Stornoway, 27 Sep 2016

 

Here come #Karl and #Lisa!

The remains of two separate tropical storms (#Karl #Lisa), currently just short of hurricane status, are heading towards our Scottish & Hebridean shores. But please don't panic; although they do add a bit of "oomph" or "turbo-boost" to our regular low pressure systems, hurricane force winds are generally *rare by the time such systems reach us. Instead, expect a regular spell of 'fiadhaich' (wild and wet) weather.

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* Occasionally these storms reach full hurricane force status in Autumn e.g. Debbie on 16/9/1961. But on average, it is during December, January and February that we suffer the most severe gales.

@eddy_weather Stornoway 23 Sep 2016

New Storm Names for Winter Ahead Issued: And Beware of Bogus Weather Sites!

Following the overwhelming success of the inaugural pilot project last year (2015-16), #NameOurStorms is being rolled out again for the coming winter by the UK Met Office and Met Eireann (the Irish National Met Service). Naming storms saves lives  - because people (including who control the infrastructures that protect us) are made more aware of the danger posed by such storms, allowing preventative and adaptive measures to be put in place against potential damage and loss.

For example, up to the mid-1990s it was common for a winter wind storm with a maximum gust of between 90 and 100mph to cause the loss of 5 to 10 or more lives across the British and Irish Isles. Today, despite the increasing severity and frequency of winter storms over recent years, the number of injuries and deaths has plummeted due to better awareness.

Here are this year's names: Some really popular ones are included this year: #Ewan #Malcolm #Oisin #Conor #Angus, though I'm perhaps less keen on #Doris (storm in a teacup?) and #Wilbert

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Final word of warning: There is an unfortunate over-abundance of unqualifed individuals proclaiming meteorological advice and expertise on the web today (e.g. Facebook 'weather' sites, Old Moore's Almanac, Exacta Weather). Many of these are operated by unqualified individuals, with little, if any, training or belief in the science of meteorology.  I strongly recommend that you take these with a pinch of salt. Certainly, do not make any safety decisions based on their forecasts  - use official sites only! 

Tip: Accredited individuals will usually have the initials RMet, CMet or FRMetS (or an equivalent qualification) after their name (in the same way that accredited trades persons have e.g. CEng, FRCS after their name). Reputable organisations are usually easily identified as having a long track record of providing met information to service providers.

20 Sep 2016, Stornoway @eddy_weather, FRMetS!

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27 February 2014, 3:46 PM
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