Some showers, and some in unusual places

A few isolated thundershowers could affect parts of Saudi Arabia between late Saturday Jan 7 and early Monday Jan 9. The highest chance, although small, is over Jeddah and central parts of central Saudi Arabia that might reach Kuwait and upper parts of the Arabian Gulf. A rather unusual spot for showers will be southest coastal Pakistan and eastern Gulf of Oman on Tuesday.

Wet and Cool for the Mediterranean

A series of cold fronts and low pressures continue to impact the Mediterranean countries, especially the coastlines, with rain and some coastal thundershowers that could sometimes affect northern Egypt. This trend is expected to continue to mid January, after which cooler weather is expected to arrive, bringing temperatures down. This colder air is expected to find its way to the northern Arabian Peninsula around and after mid January.

A sunny start for Winter

Warmer for the Arabian Peninsula, cooler after mid January

Most of the Arabian Gulf countries will experience warmer than normal daytime temperatures up to Jan 12-13. Some cities will be just 1 or 2 degrees above normal such as Muscat, and others will be 5 to 7 degrees above normal such as Kuwait and Riyadh. Temperatures will be in the 20s for most of the Arabian Gulf countries. This in contrast to the fact that January is the coldest month of the year. But temperatures will quickly go from above to below normal after Jan 14, as cold air behind Mediterranean lows moves southeastward. Of course, the impact of the cold air gets eroded by the time it reaches eastern gulf such the UAE and Oman, bringing a much less intense change in temperatures, but still cooler than normal. Daytime temperatures after mid January could fall to early teens over Kuwait and Riyadh, mid teens over Bahrain, late teens over Doha, and early 20s over the UAE and Muscat. The cities that will (not) go much above normal during the next days will be the same ones that will (not) go much below normal after mid January. Somegusty winds are likely to accompany the coldwave over the Arabian Gulf.

During December 2011, temperatures as low as 6 or 7 degrees have been recorded in inland areas, especially in suburbs near Al-Ain city where local weather stations are located. But if you look at official airport readings, Sharjah and Al-Ain airports recorded the lowest nighttime temperatures since they are away from the coasts. Upto Dec 20, Sharjah airport had 5 nights with min temperatures less than 10c while average minimum temperature has been around 12.6C, lower than average by around 2c. Al Ain airport has so far recorded average minimum temperature of 13.5C, lower than average by 1C. With next few nights looking cooler than normal, this December could end up being one of the coolest in terms of nighttime over interior areas. But it is a different story for daytime temperatures which have been normal and pleasantly warm, due to lack of cool shamal winds or cloudy rainy days.

This December has been unusually calm and dry, not over the UAE, but over much of the Arabian Peninsula. With no windy or cloudy nights, the process of nocturnal cooling was enhanced even as days remained relatively warm. During nocturnal cooling, the lower atmosphere cools down relatively quickly as earth releases its heat or radiation at night but with no incoming radiation, it cools down and oftern de-couples from the air above it. Usually cloudy or windy nights suppress the nocturnal cooling. Cooler nights have been the case over the GCC countries, especially for interior areas. As for the UAE during the next 2 nights, winds will be light and easterly in general, which tend to be drier compared to winds coming from the west. During such conditions, temperatures fall down more with lower dew points as well.

Calm, clear, and cool nights over interior areas have been the highlight of Dec 2011.

While it is definetely cooler, the region (Arabian Peninsula and Middeteranian regions) could be largely dry during the first week of December. There has been several rain systems in the northern and mid Arabian Gulf that brough meaningful rain to Kuwait, KSA, Bahrain, and Qatar. The UAE remained quite dry. Moreover some areas especially in Kuwait and KSA could continue recording lower than average temperatures in the coming days, while areas on eastern Arabian Peninsula such as the UAE could slightly warm up.

This marks the first, out of several waves of milder air, that should continue until winter takes over. Compared to a typical daytime temperature of 40c during end of September, there should be as much as 10 degrees decrease by the time November starts, and as much as 15 degrees decrease by the 2nd half of November.

So little changes every week will mount to bigger changes later on as October and November are months of transition between summer and winter.

Elsewhere, the Mediterranean region has received a few showers last week, but this will likely take on a quicker pace by mid october as Meditteranean low pressure systems gain momentum, bringing frequent weather changes and wet period.

There is only one direction for the temperature: Down!

Humid and calm nights can be an indicator of a foggy morning. As overnights temperatures get slightly cooler, and dew points still high, the chance of air parcels condensing becomes higher during this time of the year.

Astrologists prefer to consider the period around Sep 21-23 as the start of autumn as sun rays shine directly on the equator, giving way to equal days and night, and Dec 21-23 marking the start of winter. Due to temperature lag of earth, meteorologist prefer to designate the start of September as the start of autumn, and the start of December marking the begining of Autumn.

Whichever you take it, days are getting progressively shorter with less heat intake by earth. You should start noticing sunsets becoming earlier and later sunrises. Of course that applies to the northern hemisphere only. Temperatures should have started their seasonal decline, and some areas cool faster or slower than others. The mediterranean countries are likely to see changes in October, with effects reaching the Arabian Peninsula in November, as cooler air and the jet stream migrates southward again.

The UAE

As for the UAE, the next 4 weeks will bring gradually lower temperatures with coastal areas seeing settling to mid 30s by end of October during the daytime hours while inland areas continue to be warmer. However, nights should feel more comfortable especially if not humid and particulary in inland areas with temperatures in low 20s.

Dubai average maximum temperatures is 39c in Sep, 36c in Oct, and 31c in Nov (based on data for 2000-2010). As evident, Autumn is a transitional period between summer and UAE’s mild winter. Who is not in a transition anyway?

When to expect significant weathe changes in UAE? Probably in November.

September starts in a few days, so does meteorological autumn!

The months of September, October, and November marks the autmn season in the northern hemisphere. These are the months where temperatures start to decline. However, astronomical autumn starts on Sep 22/23, when length of day becomes equal to night time (Autumn Equinox).

But for folks residing in the Arabian Peninsula, it may still feel like SUMMER! It will take up to end of September and early October for some cooling to take effect. Of course. countries that are more to the north will cool quicker and faster, than compared to other countries like the UAE and the gulf countries.

What happens in autumn in the Arabian Peninsula? During the first half there will be a gradual decrease in temperatures, with warm temperatures still prevailing. But from the second half, especially by mid November, a noticable change in seasons takes place as the atmosphere gets ready for our mild winter. In November, cold fronts associated with clouds and rain begin to affect Middeteranian countries and gulf region (especially KSA and Kuwait) and often extend to Bahrain, Qatar, the UAE, and Oman. Meanwhile, during late September to early November, the Arabian Sea goes through a cyclone season once again. While rare, tropical storms and cyclones can form and sometimes affect Oman or Yemen.

It is July, the heart of summer. Heat levels are incredibly high. Out of the major Gulf cities, Kuwait city is usually the most likely one to hit the 50c mark. In fact, official temperautures recorded were as  high as 50 and 51c on July 14th and 15th, 2011. Yet Kuwait, much of central Saudi Arabia, and other interior areas are less prone to humid air that affect other coastal cities of the UAE, Oman, Qatar, Bahrain, and coastal Saudi Arabia. Even though temperatures rarely hit 50c on coastal UAE, high humidity makes it feel much worse. Luckily, several July days have been quite dry in the UAE with less humidity which usually peeks in August and September.

Aside from brief afternoon showers on and near UAE and Oman mountains, the cooler spots of Arabia remain the coastal misty city of Salalah in Oman and the cool southern Aseer mountains of Saudi Arabia where seasonal summer rainfall is quite normal.

Temperatures start their seasonal decline starting September!

There are two interesting events in this animated movie from May 1 -14, 2002. More details here.

Animated Movie of Arabian Sea Tropical Storm in May 2002. Please wait for the movie to load. Image retrieved from NOAA National Climatic Data Center