Weather warnings for Christmas Eve 2018

The Spanish meteorological sevice has issued weather warnings for La Gomera and the rest of the Canary Islands for tomorrow, Christmas Eve 2018. Easterly winds are expected to gust to 80 km/h and will bring dust from the Sahara which could reduce visibility to just 3000 metres. Rough seas are to be expected. 

This weather, called Calima here in the Canary Islands, is expected to gradually improve from Christmas day. There won't be much heat with this Calima episode as we're in mid-winter when the Sahara is fairly cold.

Light Calima this week

Forecast of dust concentration for Thursday, Dec. 6th 2018, a bank holiday in Spain

A very stable and blocking high pressure system over the Iberian peninsula and North Africa is steering an easterly airflow over the Canary Islands and this is not expected to change for the remainder of the week. It is bringing very dry and warm air from the Sahara, and from later today some dust is expected resulting in mostly sunny weather with a light Calima (click for more information).

Thankfully the Sahara is not too hot at this time of the year and recent rains over North Africa have kept the dust down, so the effects on the Canaries should be minor, but warmer than usual temperatures, dry air with mainly fresh easterly winds, strong and gusty at times, will be felt here. Make sure to drink enough water.

The weather should return to normal over the weekend, when the winds are expected to turn back to the usual NE trade winds bringing clearer air, according to most forecasting models.

Warning of calima for a few days

The dust load forecast for Friday evening by the Barcelona Dust Forecast Centre of the Spanish met. service

The present light calima conditions are expected to worsen and a much heavier dust load in the air is expected as winds from the Sahara in the east will freshen. The already summer-like temperature is set to increase, particularly in the medium to high altitudes of La Gomera, and could reach 30ºC or even more in places. The fairly high dust concentration is expected to lead to much reduced visibility of only about 3.000 metres generally, and even only 1.000 -2.000 metres at times. A status 'yellow' weather warning of these conditions has been issued by the official Spanish meteorological service for tomorrow, Thursday March 8th 2017, and remains valid until Saturday evening. Friday is expected to be the worst day of this episode of calima conditions.
Current indications are that the dust will gradually clear later on Saturday, with a return to more normal temperatures and fresh to strong north-easterly winds from Sunday. It should remain mostly sunny in the south, and cloudy spells are expected in the north.

Find out more about the so-called CALIMA...

Calima: Weather from the Sahara

The much dreaded 'calima' weather  occurs when there is an easterly stream of air coming from the Sahara desert bringing with it a cloud of fine, flour-like dust and sand and sometimes even locusts. It is often associated with easterly gales and hot dry air from the Sahara. In winter it is not too hot because at this time of the year the desert is cooler, but in summer it can feel like a blast from an open oven. The air also becomes extremely dry and can cause breathing difficulties, dry mucous membranes, eye irritation and flu-like symptoms. The sun becomes obscured to appear like a milky disk and visibility is greatly reduced. Dust from the Sahara has on some occasions even reached Northern Europe, including Britain and Ireland, depositing yellowish dust on cars, etc..

In the Canaries the worst affected areas are usually the regions in between 1500 and 3000 feet of altitude, where it can become oppressively hot, while the lower regions benefit from a cooling effect by the Atlantic, which also supplies some moisture. The Eastern Canaries are generally more at risk. On La Gomera the phenomenon usually lasts only 2-5 days and is often followed by a shower of rain which clears the air but leaves a grimy deposit everywhere. 

The following saying is true for the Canary Islands, too: ‘When the wind is from the east, 'tis neither good for man nor beast’.

More details on the Saharan air layer

(SAL) here:http://en.wikipedia.org/wiki/Saharan_Air_Layer

+Here's the official advice for Calima weather conditions and heat waves:

• Carry water with you, and drink it often ! Still water is best.
• Stay in the shade and places protected from the sun  as much as possible and/or stay cool indoors.
• You can go for a refreshing swim, but make sure to slowly adjust to the water temperature
• During daylight hours lower window blinds and/or close curtains and shutters.
• Open the windows of the house at night to keep cool.
• Use air conditioning or fans to cool the atmosphere - if unavailable, hang wet towels indoors.
• Avoid dramatic temperature variations when entering or leaving places. Adjust gradually.
• On the street avoid direct sunlight. Wear a cap or a hat, wear lightweight, light-colour clothing made of natural fibres, i.e. cotton.
• Try to walk in the shade, be under an umbrella on the beach and rest frequently in a cool place.
• Never leave children,  elderly,  pets inside a closed vehicle. 
• Avoid prolonged physical exercise .
• Take regular light meals,  drinks and foods rich in water and mineral salts, such as fruits and vegetables. They will help to keep you hydrated and replace the salt lost through sweating.
• Avoid alcohol and very hot foods as well as high-calorie foods.
• Help others. If you know of sick or elderly people living alone go to visit them regularly.
• If you take medication, ask your doctor if it can affect thermoregulation or whether to adjust or change.

Saharan dust over Canary Islands (2004) ©earthobservatory.nasa.gov 

Normal visibility Valle Gran Rey, La Gomera

Visibility during a fairly heavy spell of CALIMA (taken Feb. 5th,2013)