After this batch of wet weather in Doha, it would be very unusual to see any rain at all until October at the earliest.
By Steff GaulterFirst earthquakes, then rain, what on earth is going on in Doha?Don’t panic just yet! The earthquakes might be out of the ordinary, the rain isn’t. We often have a fair amount of rain in April in Qatar. In fact in the last 10 years, it’s rained every single year except one: 2008. In 2010 the rain fell even later in the year, on 15 and 16 May.Normally I get a steady stream of people saying to me that, “It NEVER rains this late in the year!” But this year I didn’t hear that at all. I’m not sure that’s because my message of a rainy April has been received, or whether people are just avoiding me! The rain in April can be very heavy and marks the transition between winter and summer. After this batch of wet weather, it would be very unusual to see any rain at all until October at the earliest.This year the heaviest of the rain wasn’t over Qatar, it was further south. Rain poured over Oman. The ground in Oman, as in Qatar, is baked hard by the sun for the majority of the year. It cannot readily absorb the rainfall, and even small amounts of water will sit on the surface for many hours. If the rain continues, the puddles simply become larger and larger.Although the soil might be similarly baked hard, Oman differs from Qatar in that it is mountainous. Particularly badly hit were the Hajar Mountains just to the west of Muscat. These mountains form the highest mountain range in the Arabian Peninsula, towering up to 2,980m (9,834 ft), and lie between 50 and 100km (30 and 60 miles) from the sea. As the rain poured, it hurtled down the mountainside, filling valleys which quickly overflowed. The valleys, called wadis, remain dry for most of the year, and only fill during the rains. Wadis can be dangerous, as it might be sunny on the coast, but pouring in the mountains. The wadis can become a raging torrent in a matter of minutes, with little or no warning for those on the coast. In the recent storms over a hundred residents had to be rescued as the wadis overflowed. People were stranded and some towns were cut off altogether by the floodwater. One of the worst hit places was the city of Nizwa, which lies 140km (85 miles) from Muscat on the slopes of the Hajar Mountains. The city only expects 73mm (2.9 inches) of rain in the entire year, a couple of millimetres less than Doha, but on the April 26, 35.4mm (1.4 inches) fell. A wet day in England is generally between 5 to 10mm, so you can imagine that 35mm is easily enough to cause flash flooding when the ground doesn’t absorb water, and the terrain is mountainous.Here in Qatar, people seems split over our recent unsettled weather. Whilst some people are lamenting their lack of sunbathing, others are enjoying the change; after all we all know that this will be one of the last occasions that we see rain in Qatar until about October. From here on, the temperatures will really soar. In May, the average temperature in Doha is 38oC (100oF), but that doesn’t really tell the whole story.At the beginning of the month of May the average temperature is 35oC (95oF), which most people can tolerate. However, by the end of the month, this has spiralled to a rather unpleasant 40oC (104oF). Remember, though, that this is just the average. We can expect the weather on some days to be far hotter than this – in fact, it’s likely that the temperatures will climb to 45oC (113oF) on at least one day.Clearly that’s hot, but the high temperatures aren’t necessarily an indication of unbearable weather. Dry air is easier to heat than humid air, because when you heat humid air you need to heat the air up plus the moisture in the air too. With dry air, you just need to heat the air. Therefore it takes the sun longer to heat moist air.This is why extremely high temperatures are often an indication that the air is dry. When you see a forecast for Doha during the summer months, and the temperature suddenly drops (or rises) on consecutive days, this is often an indication that the humidity is changing too.Last year, on May 5, the temperature was a baking 45oC (113oF), but the very next day the temperature climbed no higher than 40oC (104oF). The difference in the temperature was caused by the change in humidity. On May 5, the humidity was very low, just 5% at its lowest point. The winds were coming from desert of Saudi Arabia, but then the wind changed. They swung round to come from the northwest, from across the waters of the Gulf. The humidity rose dramatically, and the next day the maximum temperature was 5oC (9oF) lower.Although the actual number on the thermometer might be lower, humid heat will always feel more unbearable than dry heat. Air that is full of moisture reduces the speed that your perspiration can evaporate from your skin, meaning the body’s cooling mechanism cannot work as efficiently. The air feels hotter, and it can also make it hard to breathe, especially for asthma sufferers. Fortunately we’re not expecting too many humid days in May. Although there is usually the occasional day when the air is full of moisture, normally the month has quite dry air. The suffocating humidity of the summer is yet to come.