96L Little Threat; Arctic Sea Ice Bottoms Out at 6th Lowest Extent on Record

In the Atlantic, a small area of low pressure (Invest 96L) formed Wednesday evening in the middle Atlantic Ocean near 15°N 45°W, about halfway between the Lesser Antilles Islands and the Cape Verde Islands. Satellite loops show that 96L has a pronounced low-level spin, but only a small amount of heavy thunderstorms. Water vapor satellite loops show 96L is surrounded on all sides by large amounts of dry air. With wind shear expected to stay moderate for the next five days, this dry air is likely to keep 96L from developing. None of the reliable tropical cyclone genesis models predict that 96L will develop, and In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 96L 2-day and 5-day odds of development of 10%. The storm should move slowly northwest during the remainder of the week.


Figure 1. Latest satellite image of 96L.

Two new tropical cyclones in the Pacific
Two new tropical cyclones formed in the Pacific on Wednesday. In the Eastern Pacific, Tropical Storm Rachel formed a few hundred miles southwest of Manzanillo, Mexico. Our reliable computer models keep Rachel well offshore of the coast of Mexico, and this storm is unlikely to be a threat to any land areas. Rachel's formation gives the Eastern Pacific east of 140°W 17 named storms, 11 hurricanes, and 7 intense hurricanes so far this year. An average Eastern Pacific hurricane season sees just 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, with three of those named storms and one hurricane occurring after September 25.

In the Western Pacific, Tropical Depression Kammuri is expected to intensify into a Category 1 typhoon this weekend, but recurve out to sea well offshore from Japan.


Figure 2. Arctic sea ice age (in years) in August during 2004, 2012, and 2014. Comparing 2004 (left) to the all-time record low year of 2012 shows a huge loss of old, thick ice. Old ice is much more difficult to melt off compared to thin first-year ice, which can completely melt out during unusually warm and sunny summers. Old, thick ice has recovered some during 2013 and again in 2014, though there has not been much change in the ice aged 3 or more years. Image credit: University of Colorado.

Arctic sea ice falls to 6th lowest yearly extent on record
Arctic sea ice extent bottomed out at the 6th lowest extent in the 36-year satellite record on September 17 and is now growing, said the National Snow and Ice Data Center (NSIDC) this week. Some of the 2nd-year ice that survived the summer of 2013 has also survived the summer of 2014, so the ice pack is armoring itself a bit going into 2015 with more multi-year ice than usual. This does not mean the Arctic sea ice is on its way to recovery, unfortunately, as Steve Gregory explains in his detailed look at this year's Arctic sea ice minimum in his Wednesday afternoon post.

Jeff Masters