Heavy convective rainfall caused severe flooding in northern parts of Oman on 17 and 18 March.
More information and detailed analysis of the feature can be found in the In Depth section.
by HansPeter Roesli (EUMETSAT) and Juma Al-Maskari (Department of Meteorology, Seeb Int. Airport, Oman)
Rain amounts were considerable for the region and caused extended flash floods along the northern coast and even in Inner Oman (east of the Hadjar al-Gharbi and Hadjar al-Sharqi mountain ranges).
Rain amounts measured between 17 March 12:00 UTC and 18 March 18:00 UTC ranged from 20–50 mm at Inner Oman, to 50–100 mm on the coastal plane north of Muscat. Even higher amounts were falling over the Hadjar mountain ranges, with 168 mm on Jabal Shams (which at just over 3000 m is the highest peak in Oman).
The root cause of the event was a slow-moving trough, that originally formed over the Mediterranean two weeks earlier, then travelled along eastern parts of the Arabian Peninsula and cleared the Gulf of Oman in the evening of 18 March. The frontal system linked to the trough was re-activated on days 15 and 16. Low-level winds pushed moist, maritime air northwards from the Arabian Sea across southern Oman and eastern Yemen towards the approaching disturbance.
The advection of humid air very much resembles the conceptual model for severe convection over the Hadjar mountains as developed by Juma al-Maskari in his PhD thesis. The advection is well documented by dust streamers — on 16 March at 12:00 UTC (see upper image) the dark streamers are well aligned with the wind field at 925 hPa all along the Omani south coast. Further west the winds are from the opposite direction and drive other dust clouds in the direction of Yemen. The animated image sequence shows the evolving (low-level) wind fields on 16 March even better (see Animation, 16 March, 03:00–24:00 UTC, MPG, 5 MB).
Finally, on 17–18 March major convective cloud systems formed repeatedly over and around the Hadjar mountains (mostly over Hadjar al Gharbi, see middle image), moving out into the Gulf of Oman. The animated sequence of IR10.8 images in false colours shows the convective developments reasonably well (see Animation, 17 March 15:00 UTC–18 March 05:45 UTC, MPG, 3 MB). One should note that geographical re-projection of Meteosat images in that area elongates the clouds in the east-west direction. The same IR10.8 sequence overlaid with the geopotential and wind field at the level of the dynamic tropopause shows the coupling of the convection with upper tropospheric dynamics (see Animation, 17 March 15:00 UTC–18 March 12:45 UTC, MPG, 5 MB).
Meteosat-8 Dust RGB Image
Dust RGB with wind analysis on 16 March at 18:00 UTC
Dust RGB with wind analysis on 17 March at 00:00 UTC
Dust RGB with wind analysis on 17 March at 06:00 UTC
Dust RGB with wind analysis on 17 March at 12:00 UTC
Meteosat-8 IR10.8 Image
Met-8, 18 March 2007, 00:45 UTC
Channel 09 (IR10.8, colour enhanced)
Animation (7 March 15:00 UTC–18 March 05:45 UTC (MPG, 3 MB)
Animation (with 2PVU field) 17 March 15:00 UTC–18 March 12:45 UTC (MPG, 5 MB)
Category 4 tropical cyclone Gonu hits the northern coast of Oman (4 June 2007)
Cold front with thunderstorms over the Middle East (6 April 2006)
Moisture boundary across the Arabian Peninsula (15 March 2006)
18 March 2007, around 07:00 UTC, Muscat
Full Resolution (JPG, 829 KB,Credit: J. Al-Maskari)
Picture 1 showing the situation in Nizwa (18 March, JPG, 41 KB, Source unknown)
Picture 2 showing the situation in Nizwa (JPG, 36 KB, Source unknown)
Movie from Samail Wadi (MP4, 1.4 MB, Source unknown)