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Severe Cyclone Gonu Prepares to Strike the Gulf of Oman

By: Dr. Jeff Masters, 5:34 AM GMT on June 05, 2007

An unusual event is happening over the next 48 hours, as the first tropical cyclone with hurricane-force winds, and major hurricane-force winds at that, is approaching the Gulf of Oman, to strike the eastern coast of Oman, curve northward, and make landfall on the coast of Iran. In the tropical cyclone best tracks and the modern era of weather satellites, there is no record of such an occurrence.

Today, Steve Gregory and I will be guest-hosting the blog, while Jeff is on vacation, to provide current information on Severe Cyclone Gonu. I'll provide some background on the areas that are currently forecast to be in the path of this dangerous cyclone, followed by Steve's Monday evening surge forecast and assessment based on the most recent JTWC track and intensity forecast, which currently calls for sustained winds of 115 kt when first passing near the coastline of Oman.

Updates during the day will be posted on my blog, The View From the Surface.

As I write this it is late in the evening in the central US, but the day has already begun in the Middle East. Distant cirrus from Gonu have already started to cloud the Gulf of Oman, and over the course of the day there, conditions will deteriorate along the eastern coast of Oman as the tropical cyclone approaches. Overnight, the core of Gonu will approach the tip of Oman, with the eye passing offshore just before dawn, and the bulk of the surge occuring along the eastern coast some time shortly before that. By midday the next day the worst of the storm will have passed the southernmost portion of the coast, and the core of the storm will be directly east of Muscat, the capital of Oman, home to over half a million people. Right now the forecast has the storm passing just offshore, but if the track shifts further east, the most damaging winds of the cyclone will remain over water. This will lessen the damage to Oman, but will likely result in a higher intensity when making landfall in Iran.

--Margie Kieper

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Those who live along the Gulf of Mexico are well aware of what it means for a major hurricane to make landfall. Even if they've never experienced it themselves, they have relatives or members of their community who have experienced it. And in many places they can see the damage that remains.

Imagine that you live directly on the Gulf, but in a place where it hardly ever rains, and where a hurricane has never hit, for at least a generation -- for more than sixty years. Your community and many like yours are situated not only directly on the water, but near or in large dry riverbeds on the coastal plain, which is a narrow strip of sandy shoreline that is the dropoff for the three-thousand-foot mountain range behind it. Even many of the roads up into the mountains are in these dry riverbeds, which course through deep canyons as they rise into the heights. You don't have any idea what it might mean to experience winds of over 100 miles per hour, whipping up sand, and torrential rain against these mountains that can turn the riverbeds into conduits for dangerous flash floods. And you don't have any idea what storm surge is, and can't conceive of wind-driven high waves that could break against the shoreline and leave nothing behind.

This is the eastern coast of Oman, where communities line the shoreline which is shortly going to be experiencing a major hurricane. We can only hope that the danger is understood and that all of these communities have evacuated to higher ground and a safer location.

Below are two images of the city of Sur, showing how the community is built right along the water's edge:


closeup of Sur

The first image below shows one of the large winding dry riverbeds, and the second close-up shows a village built right where this riverbed empties into the gulf.

dry riverbed

community built in riverbed

These images show an industrial facility on the shoreline right at the tip of southeastern Oman, with an airstrip and a small community -- all of which could be gone in twenty-four hours, from surge, if the storm passes close to this area as currently forecast.

southeastern tip of Oman

closeup of southeastern tip of Oman

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Steve Gregory's Monday Evening Forecast for Gonu

Severe Cyclone GONU in the Arabian Sea is currently heading NW at 14KTS (Faster than the JTWC Forecast) and is located 135NM SE of the eastern most 'tip' of Oman, and 180NM SE of Muscat. The storm is now a very strong CAT 4 - with an estimated pressure of 904mb, and wind gusts to 155Kts.

Based on imagery over the last 6 hours - the storm is under-going an Eyewall Replacement cycle, and so the first early morning VIS image (right) shows the eye is now covered with cirrus. As a new eyewall is developing (based on Micro-wave imagery) and will complete this cycle right about the time it gets to the Oman Gulf.

The track the storm takes as it nears the Oman coast is extremely critical in terms of intensity as it is entering the Gulf - and how severe the damage will be. There ocean heat content of the water on the SE FACING side of Oman is lower - and if the storm travels close to that location (as shown on the NAVY chart) the storm will likely weaken further during the day to a low end CAT 3, and then hit the Iran coast as a strong CAT 1 on Wednesday.

If the storm tracks 50-100NM NORTH of the coast as it enters the Gulf of Oman - though the water is shallower there, the SST's are very high (32degC) and with the storm further away from land, and over very warm water - it is likely to hold onto CAT 3 intensity for an additional 4-6 hours as it moves NW.

There is a large oil facility and large airport located right at the eastern 'tip' of Oman - and I counted at least 6 major 'ports' on Satellite imagery along the Oman coast up to 100 miles WNW of Muscat.

On the opposite side of the Gulf is the Iranian coast - with numerous 'cove inlets' each with loading docks and port facilities. At least 9 facilities I could count from the Iran/Pakistan border west to the area I show landfall (Magenta Arrow on the diagram below). Offshore platforms were also seen in a few locations.

Steve Gregory Gonu surge forecast

The Storm surge shown (10-15 ft) will almost certainly hit the Iran coast - even if the storm weakens to a strong CAT 2 late Tuesday (NY time). The Eastern tip of Oman will likely also experience 10-15 foot surge due to the close proximity of the storm track. Further up the Gulf, before reaching the Straits of Hormuz - storm surge heights of 1-4 feet are expected on the Oman side, and 4-possibly 6 feet on the Iranian side near the entrance to the Straits. Significant wave heights will be 20-30 feet, dropping to 15 feet near the Straits.

This is an unprecedented event. NO CYCLONE has ever entered the Gulf of Oman. And there are no custom 'storm surge' models available for that area. This forecast is based on my experience and subjective analysis of the seabed slope and storm surge interaction with the sea floor. Considering the region has never experienced a hurricane, let alone a strong one it is highly unlikely the loading facilities or platforms were constructed to withstand the forces - both wave action and wind force - that they will experience. Significant, damage will occur. How much long term damage, and the volumes associated with it - can not be determined at this time.

--Steve Gregory

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.