Friday, September 13, 2013

Hurricane Humberto influences weather in Canaries. Updated below

I'm not superstitious but today is Friday the 13th in the year '13 and the first hurricane of the season (named Humberto) is not moving west and then north over the western Atlantic, as tropical storms should do, but this tropical storm system is moving north in the eastern Atlantic after having formed near the Cape Verde Islands and this results  in our  weather being adversely affected today with some welcome rain.
lt is important to stress that hurricane Humberto will NOT hit the Canary Islands, but the mass of warm and moist air that the storm system is pushing towards the Canary Islands could produce some heavier spells of rain here today, while winds should remain mostly light to moderate, with a few stronger gusts only on the higher mountains.
It must also be said that the whole scenario might develop differently and the Canaries might not even get the desired rain, as the jury of meteorologists is still out discussing the unusual and difficult case.

The situation:
The Canary Islands are coming under the influence of an area of warm moist air from hurricane Humbert, located about 700 miles to the SW of the islands with sustained wind speeds of about 85 mp/h near the centre (984 hPa) and stronger gusts. The likely interaction of the advancing air mass with upper level low pressure to the north of and close to the Canary Islands could cause instability today, Friday. The entire archipelago is affected, but especially mountainous areas in general and central and southern zones of Gran Canaria and Tenerife. 
Warning in effect until midnight tonight: WARNING CANCELLED
Probability of persistent heavy rainfall which may be accompanied by thunderstorms. Precipitation could accumulate up to 30mm in 6 hours with central and southern areas of the islands at a slightly higher risk. Hiking in mountainous terrain as well as in narrow valleys and ravines is dangerous due to the possibility of flash floods and rockfalls, etc.
Hurricane Humberto is expected to weaken later today while tracking more westerly away from the Canary Islands leading to an improvement in the weather. However, the upper low just north of the Canaries is likely to remain and the risk of well scattered light showers will persist over the weekend. Sunny periods and continuing warm temperatures in the mid-20s (ºC) are also expected.
Sat. image with enhanced water vapour at 6pm last night...
Humberto is starting to weaken and tracking more north-westerly, but still feeding moist air towards the Canaries. Humberto is expected to be downgraded to a topical storm later today.
Personally I don't think that we'll get much out of Humberto in the Canaries today.
...and at 6am this morning. Now Humberto appears less organised and starting to move away to NW.


News just in: Humberto has been downgraded to a tropical storm and lost its hurricane status and characteristics with max. sustained winds now 65 mp/h (100 km/h), tracking WNW (300º) now. All as expected and forecast except that a band of heavy showers was lying just a few miles south of the Canary Islands all day up to now without ever coming in over the archipelago. Very frustrating. I can see it from my window and it is as if someone was keeping it away and in an orderly straight line with a ruler (see rain radar image). A possible explanation is that a layer of dry air is persisting over us which is holding the ruler, but I'm not giving up just yet.

Humberto continues to weaken while moving away from the Canaries without having left any rain worth mentioning here. So close and yet so far! Anyway, some of Humberto's moist air has fed into the minor low north/north-east of us and this low in turn might send some showers down to us with the trades over the next few days. I'll end this post with a cartoon that was circulating on the web tonight. On the 'No Entry' sign it says: ''Area reserved for trade winds'' ...

1 comment :

Andy said...

Here in Lamzarote it is the calm before the storrm. Very weird morning not a breath of wind all the leaves are still with blue sky.