The tropical Pacific Ocean has transitioned from last winter’s El Niño conditions to a cool La Niña, as shown by new data about sea surface heights, collected by the U.S-French Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite.
This OSTM/Jason-2 image of the Pacific Ocean is based on the average of 10 days of data centered on Sept. 3, 2010. A new image depicts places where the Pacific sea surface height is higher (warmer) than normal as yellow and red, with places where the sea surface is lower (cooler) than normal as blue and purple. Green indicates near-normal conditions. Sea surface height is an indicator of how much of the sun’s heat is stored in the upper ocean.
La Niña ocean conditions often follow an El Niño episode and are essentially the opposite of El Niño conditions. During a La Niña episode, trade winds are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La Niña episodes change global weather patterns and are associated with less moisture in the air over cooler ocean waters, resulting in less rain along the coasts of North and South America and the equator, and more rain in the far Western Pacific .
As of 5 AM EDT Friday, Igor has top winds of 125 mph and was centered about 760 miles south-southeast of Bermuda. Hurricane Igor is still heading toward the northwest at 9 mph. A hurricane watch remains in effect for Bermuda.
Hurricane Igor is a very large category 3 hurricane on the Saffir-Simpson wind scale. Slight fluctuations in intensity are forecast over the next 2 days, but the storm is expected to remain a powerful hurricane into the weekend.
Igor should continue moving toward the northwest into Saturday, with a northward turn anticipated over the weekend.
Hurricane Igor weakened to a Category 4 storm late Monday as it continued to churn far out in the Atlantic Ocean. As of 11 p.m. AT, Igor’s top sustained winds were about 220 km/h, down from earlier winds of 240 km/h.
“Some fluctuation in intensity is likely during the next couple of days. But Igor is expected to remain a powerful hurricane through Wednesday,” said forecasters at the U.S. National Hurricane Center in Miami.
Igor was centred about 1,260 kilometres east of the northern Leeward Islands, and the storm was moving west at 15 km/h. The hurricane is expected to turn toward the west-northwest Tuesday followed by a turn toward the northwest early Wednesday.
Farther back is tropical storm Julia, which formed on Sunday. Julia is nearing the southern Cape Verde Islands and could become a hurricane this week.
Flooding is the biggest concern with Hermine, especially as the winds start to diminish later today. In fact, flooding will be an ongoing concern through at least the middle of the week. Four to eight inches of rain will be unleashed from central to south-central portions of Texas through tonight with locally higher amounts. Cities included in the zone with the greatest flood risk today into tonight include San Antonio and Corpus Christi.
Flooding will quickly ensue in low-lying and poor drainage areas. Small streams and creeks will rise rapidly and overflow their banks. Residents, especially those in flood-prone areas, should be prepared for possible evacuation orders.
Officials may be forced to close roads that become inundated with flood waters . Even if barricades are not in place, motorists are reminded never to drive through a road covered in water. The roadway underneath may be washed away or the water’s swift current could sweep away your vehicle.
