A strong sand storm formed on Wednesday Feb 2nd over KSA, with blinding visibility and strong winds.

Sand and dust, in purple color, can be seen over KSA and Iraq.

Rainfall:

Rainfall exceeded 40mm over Masirah island. Other areas received between 5 – 30 mm of rain. With rain continuing for a few more days, several areas of coastal Oman might reach 50mm of rain.

Impact over Oman mainly:

Eastern coasts of Oman and possibly northeastern coast of Yemen are expected to receive some showers and over several periods between Sunday and Thursday. Showers could reach northerneastern Oman coasts. Other interior areas will experience cloudy weather. There will also be some clouds over parts of the UAE, but no rain is likely. And the Hajar mountains might receive some isolated afternoon showers as well.

Rain not part of the “cool” season

While these showers over Oman are arriving in end of October and early November, they are not the first rain of the cool season. It is part of the tropical activity of the Arabian Sea which goes through 2 windows of tropical activity. The first is in May and June, which produced violent cyclones in the past few years. The second is between October and November. The current low pressure is weak compared to tropical standards. But, it is expected to deliver much needed rain to Oman coastlines.

Where next?

There remains some uncertainty to the future behaviour of the low pressure. But most likely, it stall off the Omani coasts for 2-3 days, resulting in some prolonged rainfall over coastal Oman. Stay tuned for updates.

Infrared Satellite image shows convective clouds of the tropical low impacting Oman. Oct 31, 2011.

Infrared satellite image Oct 30 shows the low pressure getting closer to Oman.

Water Vapor image of the Arabian Sea Low. Oct 28, 2011.

While Saudi Arabia and the Mediterranean continue to be prone to some showers during the month of May, a change into a dry weather pattern is likely to settle in by end of May if not before. A semi-permanent mid-level subtropical high pressure starts strengthening with a suface heat low over Arabia.

By end of May, some eyes will shift eastward over what happens over the Arabian Sea. The indian monsoon usually starts in late May over southwest India. In some years, a vortex (associated with the developing monsoon) can transform into a tropical storm that warrants the attention of countries located along the Arabian Sea. 

Heading into the summer months, tropical moisture inflow results in seasonal rainfall over southeast Oman (Salalah), southern Saudi Arabia, parts of Yemen, and occasionally over the Hajar mountains where heat, moisture, and lifting of mountains take place.

A long-term average 500mb heights during May. Orange shading indicates a high pressure system that forms during the month of May. Image retrieved from ESRL.

IR Satellite image shows thunder clouds over Saudi Arabia on April 24th, 2011.

A few thundershowers formed over Hajar mountains. Chance for other areas remain small.

UAE forecast: Small risk of rare late-April isolated showers between Tuesday PM and Wendesday AM. This is in response to a mid-level low passing eastward with a trough extending to Arabia. Chance remains small, but mountainous areas, western region, and coastal cities have a higher chance. Even though the overall chance is low, thundershowers forming this time of the year are capable of producing high downdraft winds that can result in localized dust.

As for the Arabian Peninsula, this eastward moving mid-level low will result in showers and thunderstorms over Saudi Arabia, possibly Kuwait, and Iraq on Monday and early Tuesday. By Tuesday night, isloated showers start forming over eastern Arabian Gulf including the UAE, but the chance for Qatar and Bahrain is small. By Wednesday and Thursday, unseasonal thundershowers are expected to form Oman mountains and southeastern coastlines, then extend to Yemen.

Starting April 29th and possibly continuing until May 1st, more showers and thunderstorms are expected to form over Saudi Arabia, Kuwait, and Iraq as another mid-level low starts crossing the Mediterenean.

rainfall from April 20 to 23, 2011

Thunderstorms have been raging across Saudi Arabia and Iraq for the last few days. Localized dust storms have formed in response to high downdraft winds from the storms. Some dusty weather was observed in Kuwait and Riyadh.

As a mid-latitude low moves progressively eastward across the Mediterranean and continuous flow of equatorial moisture, more showers and thunderstorms are expected to form over northwestern, central Saudi Arabia, Kuwait, Iraq, with rain showers over western Iran and the Mediterranean. Of particular interest is the area of heavy rainfall expected over NE Syria and NW Iraq. This active weather will continue until late Satuday April 23, just before a new spell of active weather starts in Arabian Peninsual again that might progress from northern to eastern Arabian Gulf by end of April (more details later).

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Thunderstorms are expected to hit central and western Saudi Arabia, for several days starting today.
Some thunderstorms are also expected to affect Yemen, Iraq, and Kuwait possibly later this week. Thunderstorms could produce high winds that result in localized dust storms in some places.

The image above shows total expected rainfall for the next 180 hours.

Eastern Arabian Gulf countries of the UAE, Qatar, Bahrain, and Oman will experience a stable weather.

March 15 – 18:

A third round is expected over Southwestern Saudi Arabia, especially over red sea coast and mountainous areas including Jeddah and Mecca. Scattered thunderstorms with heavy rainfall are expected to erupt during the afternoon hours of Tuesday Mar 15th and continue to Thursday. Thunderstorms could also hit western Yemen and much of southern Red Sea.

A 500mb shortwave trough left behind the main 500mb low from the prior round of thunderstorms will result in lifting of air parcels. Aided with high Convective Available Potential Energy (CAPE), thunderstorms are likely to occur. However, convection inhibition is quite large on Tuesday, which could make thunderstorms more scattered and delayed until the afternoon, but it is expected to reduce further by Wednesday, setting the stage for stronger thunderstorms. 0-6 KM wind shear is expected to increase on Wendesday with greater mid-level lapse rates. Basically the risk of damaging winds, large hail, and long-lived thunderstorms is higher on Wendesday. But the risk of localized heavy rainfall from thunderstorms exists from Tuesday to Thursday.

March 7 – 14:

Several thunderstorms have been pounding parts of Saudi Arabia and Kuwait. Exceesive rainfall from long-lived thunderstorms over parts Saudi Arabia dumped as much as 75mm in few hours. 3 people have been killed in Al Ta’if.

The below image show actual rainfall observed during the 72 hours ending on Mar 12 at 3 GMT. Of course, rain has also fallen prior to 72 hours and is expected to continue for a couple of days after Mar 12.

Forecast: This round is expected to be stronger and will affect northern Arabia as an upper low deepens over the Mediterranean, with rain and showers also extending to Iraq and Iran. It will start during the evening hours of Monday March 7th as scattered thunderstorms over western Yemen, western Saudi Arabia, before spreading to parts of northern Saudi Arabia and Kuwait in response to a long-wave trough and will continue until Tuesday. Some thunderstorms could be strong over northern Saudi Arabia, Kuwait, and Iraq as increasing CAPE, relatively low CIN, high mid-level lapse rates of 8 C/Km, and high 0-6 KM vertical wind shear. The system is expected to re-generate starting Wednesday (and progressing until Monday March 14) as the 500mb low over the Mediterranean deepens and moves further south with a short-wave trough developing later. Aided by tropical moisture flowing northward, a belt of clouds, rain, and some organized thunderstorms could form along frontal boundary with precipitation becoming potentially heavy accross eastern Saudi Arabia, northern Arabian Gulf, Iran (with mountain snow), Iraq, and the Mediterranean. Some rain showers may reach Bahrain and Qatar. Becoming warmer over the UAE , Oman, eastern Iran, and Pakistan.

March 4 – 6:

The first round is relatively weaker with scatterred showers and should start during the evening hours of Friday March 4th over parts of western Saudi Arabia. The scatterred showers are expected to progress eastward during the following 48 hours towards central Saudi Arabia, the Empty Quarter , southern and western UAE (!!) and parts of interior and eastern Oman. Some clouds could cover other parts of the UAE with a chance of a shower. This round of showers continue the same pattern of below-average rainfall in much of the UAE, except for the western region where rainfall has been average to above average. Moreover, the pattern of unusual path of rain continues in the region as this round delivers rain in the Empty Quarter!

Saturday March 5th: Rain Showers in southern UAE.