Heavy rainfall in United Arab Emirates & Oman

By HansPeter Roesli (EUMETSAT) and Hamaid Albadi (Department of Meteorology, Seeb International Airport, Oman)

During the period 21–24 February 2006 the moist boundary layer together with the passage of an upper trough led to heavy (mostly convective) rainfall over the United Arab Emirates and Oman. The arrival of the rain was timely forecasted by DGCAM, the national meteorological service of Oman (see front page of the Oman Daily Observer of 22nd February).

A detailed description of the evolution of the situation including weather charts, rainfall data and pictures of the severe event from Oman may be found in the report Rainy weather affecting Oman during the period from 21st to 25 February 2006 (H Albadi). The convective evolution may be followed in the Airmass RGB images shown below that mark the major convective events during the period 22–24 February 2006.

The evolution of the boundary between the dry and moist boundary layer over the peninsula may be followed by a sequence of Dust RGB images from 21-25 February at 11:45 UTC (15:45 local time). This particular selection is based on the fact that the moist boundary layer (blue hue over arid areas) shows best in the afternoon hours when the underlying surface temperature is at its maximum.

The first convective cells close to Riyadh can be seen in Figure 1.

Figure 2 shows the considerable convection along the Trucial Coast.

The major convective cells start developing just west of the Hajar al Gharbi and Hajar ash Sharqi mountain chain can be seen in FIgure 3.

Figure 4 shows single major convective cell moving eastward from Jabal Akhbar (Jabal Shams peak, 3000m high) towards the coastal area of Muscat. New developments in the most southern part of Oman (Zufar) showing weak cyclonic circulation.

Figure 5 shows the new cyclonic development evolve into further major convective activity; cyclonic signature is now clearly visible.

Figure 5 shows the last significant convective cells are developing.

The rapid weakening of remnant convection can be seen in Figure 7.

Practically the whole Arab Peninsula is covered with low-level moisture, partially obscured by thin cirrus clouds that happen to have similar colour shade (Figure 8). Elongated dark north-south oriented feature in the middle of Saudi Arabia is the Jabar Tuwaya mountain range.

The situation is hardly changed in Figure 10, although in the north western part of Saudi Arabia (Tabuk–Al Madinah) the boundary layer appears to be somewhat drier than on 21st. Some convective activity (without noticeable precipitation) develop along the Gulf coast. West of the Red Sea, over Sudan, lifted dust can be seen, which was already present the day before.

The dry air does not move much but forms a clearer boundary with the moist air still covering the southern part of the Peninsula (Figure 11).

Figure 12 shows the dry air pushes south-eastward and convection is confined essentially to Oman.

Except for tiny pockets, the whole Peninsula is now swept by the low-level dry air. Only insignificant convective cells are present over the coastal area of Oman and the adjacent Indian Ocean (Figure 13).

Additional content

Animation Met-8 Airmass RGB composite (20 February 23:45 UTC–25 February 11:45 UTC)
Animation Met-5 IR channel (21 February 00:30 UTC–24 February 15:00 UTC)
Animation Met-5 VIS channel (21 February 00:30 UTC–24 February 15:00 UTC)
Report from H Albadi