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.

A period of enhanced convective precipiation is expected to start on Sunday April 10th, 2011 and continue for a few days over the Arabian Gulf, and parts of the UAE, northern Oman, Qatar, Bahrain. Convective precipiation refers to rainfall falling from towering cumulus clouds that often develop into thundershowers and even thunderstorms. Expected rainfall is likely to take on a scattered pattern, which means not all areas will receive rain.

The convective activity is expected to shift accross the highlighted area (see above image), from eastern Arabian Gulf and the UAE on some days, to mid Arabian Gulf on other days. In some days, rainfall might be favored over open waters of the Arabian Gulf, while on other days it could be land-based.

The meteorological story behind it is the existence of relatively high dew point temperatures (surface moisture of a maritime tropical air mass) along with converging and rising surface winds. Added with weak to moderate lifting from subtle vorticities advections associated with a longwave trough extending from an upper low over southeastern Europe, convective clouds are expected to form. The small-scale (mesoscale) features of convective precipiation will boil down to areas where right surface and upper-air conditions meet and result in moist convection. It will all depend on intensity and location of surface winds, temperature, dew point, in addition to convective available potential energy (CAPE), convection inhibition (CIN), upper air lifting, and vertical wind shear.

Let’s take it day by day, and determine the area favored for convective precipitation.

Sunday April 10th – Monday April 11th (AM):

• Areas prone to convective rain: Open waters of the Arabian Gulf (primary). And southwestern, northern, and central UAE (secondary).
• Again, not all areas are expected to receive rain as thundershowers will take on a scattered pattern
• T-Showers are expected to start forming during the afternoon hours of Sunday along an initiation zone of confluent surface winds over southwestern UAE extending to eastern Arabian Gulf. These are the areas where the first convective clouds are expected to form.
• After that, those convective clouds are likely to move on an easterly direction towards coastal cities of the UAE.
• Thundershowers forming over land during the day might be high-based, with less rainfall falling from them due to evaporation. However, thundershowers forming over open waters of the Gulf could contain more rainfall.
• During the evening hours of the day, thundershowers could spread more over the offshore waters of northeastern UAE and continue until the morning hours of Monday.
• I must say that although CAPE could be on the low side, high vertical wind shear between 0-6 KM above ground level could produce some long-lived thunderstorms that could potentially be strong with hail.
• If you feel a sudden cool breeze, be sure that a thundershower is nearby and watch out for the possibility of stronger winds.
• Some heavy thundershowers with high winds were reported in various parts of the UAE during the evening hours of Sunday April 10th.

Monday April 11th :

• A few scattered showers, but less widespread some scattered evening showers and maybe a few thundershowers developing over southwestern UAE during the late hours of Monday April 11, and continuing to early hours of Tuesday.
• Due to the existing cloud cover and less solar heating, convective energy (CAPE) could be less, lowering the chance of thunder activity. Thundershowers are also expected to extend to central Saudi Arabia and parts of Oman.

Tuesday April 12th:

• Reduced activity over the UAE. A few isolated showers in southern UAE and parts of Oman during early Tuesday.
• The area of convective activity shifts to mid Gulf. Late evening thundershowers and thunderstorms developing over mid Arabian Gulf, affecting Qatar, Bahrain, nearby Saudi Arabia, and western UAE.
• Chance of late night thundershowers over northeastern UAE, especially after midnight.
• But generally, the UAE remains under the area prone to showers.

Wednesday April 13th:

• AM scattered showers and a few thunderstorms over various areas of the UAE, Qatar, Bahrain, eastern Saudi Arabia, eastern and mid Arabian Gulf.
• PM: isolated showers, otherwise partly cloudy over the UAE. Risk of thundershowers continue over Qatar, Bahrain, eastern Saudi Arabia, and mid Arabian Gulf. Some may reach the UAE during late Wednesday.

Thursday April 14th:

• AM: A few showers around mid gulf, Qatar, Bahrain, eastern Saudi Arabia.
• PM: Risk of thundershowers continue over Qatar, Bahrain, eastern Saudi Arabia, and mid Arabian Gulf.

 

Friday April 15th – Sunday April 17th:

• A weak cold front with westerly winds starts arriving in the eastern Arabian Gulf.  A few rain showers (sometimes with thunder) could form over different parts of the Qatar, Bahrain, eastern Saudi Arabia, and the Arabian Gulf. Chance exists for northern UAE. Slighly cooler winds to follow.
• This is the last period of unstable day in this weather system.

Is this an apology by weather itself for the dry winter here in the UAE?! Well, hot weather and rain sound like Double Standards!

Expect a detailed analysis of the upcoming weather!

Another dust storm hits Kuwait. April 4, 2011. Hopefully, the upcoming showers will provide a respite from the dust.

April is transitory month between winter and summer. The jet stream is moving northward with longer and warmer days ahead. But northern Arabia remains under the impact of migratory lows.

During the next few days, an area of lower upper-air pressure is expected to move across the Mediterranean with a trough extending to Arabia. Coupled with daytime heating, afternoon and evening isloated thundershowers are likely to develop over parts of northern and central Saudi Arabia, possibly Kuwait, and northern Arabian Gulf. Gusty and dusty southerly winds are also likely as dusty winds reached 55 km/hr with reduced visibility.

What will be the impact over other Gulf countries?

The dark purple spot marks the sandstorm

Northwesterly winds will push the dust/sand southeastward accross the Arabian Gulf countries of Bahrain and Qatar. However, the impact might not be as severe as it was over Kuwait as sand and dust particles get dispersed and northwesterly winds blowing over the Arabian Gulf water will have less fresh sand to kick up into the air.

Expect dusty and windy conditions in the UAE on Saturday March 26th, but not as severe as it was in Kuwait.  On Sunday and Monday, there will be cooler westerly winds over the UAE with rough sea.

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.

The Middle East is probably the last region that comes into any person’s mind with regard to weather-related fatalities and disasters. Here are notable weather events in the Middle East in 2010, starting and ending with the typically very dry Egypt (!!) :

• At least 10 fatalities in Egypt due to heavy thunderstorms and flooding rain Jan 17th and 18th
• Strong thunderstorms resulting in 4 casualities in the UAE on Feb 28th
• Heavy thunderstorms in Saudi Arabia in April, May, and July which resulted in at least 7 fatalities
• The infamous cyclone Phet (see above image) killing at least 24 people in Oman in June
• Pakistan disasterous floods in August
• Damaging Eastern Miditerranean winter storm in December, after prolonged drought and forest fires
• Red Sea storm killing at least 4 in Saudi Arabia and at least 5 in Egypt in December

I will let you decide whether those weather events were really severe or people in the Middle East are generally not prepared to handle such weather events.

Riyadh heavy thunderstorm (click here)

Tons of rain and thunderstorms have affected Saudi Arabia and other parts of the Arabian Peninsula.