Meteorologists say four tropical storms all raging at the same time, are a first

September 2015 – CLIMATE – Meteorologists are calling it a first: Not one, not two, but three major hurricanes were in the eastern Pacific at the exact same time on Sunday. Now, a fourth storm is joining the swirling trio. Tropical Depression 14E, now dubbed Kevin, has been upgraded to tropical storm status. Warm sea surface temperatures and a moist environment could intensify the storm over the next 24 hours, the National Hurricane Center reports. Thereafter, drier air is forecast to get into the circulation, leading to weakening. “Kevin is forecast to degenerate to a remnant low by day three and dissipate around day five,” according to the NHC. The storm is expected to track northward over Mexico before turning westward as the cyclone weakens.

According to the National Hurricane Center, a tropical depression is a tropical cyclone with a maximum sustained surface wind speed of 33 kt (62 km/h). It’s the first stage of tropical classification, before development into a storm, or a hurricane. Hurricanes Ignacio, Jimena and Kilo were all at Category 4 status simultaneously over the weekend, with sustained winds of 209–251 km/h according to the National Hurricane Center. Jimena is now a Category 2 hurricane as of Thursday, with winds of 176 km/h, and is expected to weaken throughout the week. The closest storm to Hawaii, Ignacio, is running parallel to the Hawaiian archipelago, prompting hurricane warnings in surrounding waters and high surf warnings on the islands, but the storm was downgraded to tropical storm status on Wednesday.

Ignacio has maximum sustained winds at about 120 km/h as of Thursday morning. Little change in strength is forecast through the next 24 hours, the NHC reports. As the storm tracks northwestward, it is expected to weaken. Kilo became a typhoon as it moved west of the International Date Line, sustaining winds of 160 km/h Wednesday. Kilo has since been downgraded to a Category 2 storm. However, it is expected to strengthen. Meteorologists forecast gusts could hit the 204 km/h mark by Thursday afternoon. Nestled in the centre of this hurricane party is Hawaii, but despite the dangerous-looking neighborhood, the islands look like they’ll get by without much impact.

This very rare cluster of powerful storms is due in large part to El Nino, a climate phenomenon that increases water temperatures in the eastern and central Pacific. Tropical cyclones typically only form when water temperatures are above 27.7oC. As the water warms above that threshold, hurricane formation not only becomes more likely, but storms that do form are more powerful. It’s also due in part to another El Nino effect. During years when El Nino is present, shear — the difference between wind speeds at different altitudes — is less than normal. Too much shear can destabilize tropical storms, while less sheer allows them to endure. The Pacific trio aren’t the only odd tropical phenomenon on Earth just now. –The Weather Network

contribution Niebo