Meteorological Items of Interest (including a hurricane)

Soon To Be Hurricane Isaac

Isaac is a tropical storm currently located south of Puerto Rico and heading for Haiti and Cuba. After rolling over those land areas for several hours, and reaching the southeastern Gulf of Mexico, Isaac is expected to become a modest hurricane, likely to menace the west coast of Florida and the Florida Panhandle and nearby Mississippi. Conditions are actually right for Isaac to become a fairly strong storm, even though at the moment it is very poorly organized.

Arctic Cyclone

The other storm of interest is now historical, but worth a mention. This was the arctic cyclone that occurred over the Arctic earlier this month. I mentioned it before in relation to sea ice melting, but I just noticed a nice writeup about it on the NSICD web site:

The Great Arctic Cyclone of 2012

A low pressure system entered the Arctic Ocean from the eastern Siberian coast on August 4 and then strengthened rapidly over the central Arctic Ocean. On August 6 the central pressure of the cyclone reached 964 hPa, an extremely low value for this region. It persisted over the central Arctic Ocean over the next several days, and slowly dissipated. The storm initially brought warm and very windy conditions to the Chukchi and East Siberian seas (August 5), but low temperatures prevailed later.

Low pressure systems over the Arctic Ocean tend to cause the ice to diverge or spread out and cover a larger area. These storms often bring cool conditions and even snowfall. In contrast, high pressure systems over the Arctic cause the sea ice to converge. Summers dominated by low pressure systems over the central Arctic Ocean tend to end up with greater ice extent than summers dominated by high pressure systems.

Click through to see pertinent graphics.

Historic Arctic Sea Ice Melt

That cyclone is interesting because it caused the breakup of a lot of sea ice, which was just about to melt anyway. But it was apparently fairly impressive for the scientists who study the region to have their view of the arctic blacked out for a few days during this great storm, then when the storm cleared, to see a lot of open water where before there had been ice.

It is starting to look like the amount of sea ice in the Arctic will reach an all time low (for the period it has been accurately measured) in a few days. There will still be at least two, probably three weeks of melting to follow that, so expect this year to be the lowest ever known for arctic sea ice. When this is confirmed or I have more info on it I’ll let you know.