Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 2:54 PM GMT on November 02, 2006
An unusual storm with the satellite appearance of a hurricane formed 900 miles off the coast of Oregon yesterday. The storm is a hybrid between a warm-cored tropical cyclone, cold-cored extratropical cyclone, and an uncommon type of winter storm called a Polar Low. Since we're not really sure how to classify this odd beast, I'll call it "Thingamabobbercane". Thingamabobbercane is being called 91C at the Navy web site.
Figure 1. Thingamabobbercane forms 900 miles west of the Oregon coast, November 1, 2006.
Thingamabobbercane formed from a cold-cored extratropical storm that spent two days drifting over relatively warm waters of about 59-61F (15-16C). These temperatures were warm enough to warm the core of the storm and generate a cloud-free "eye" and an "eyewall" of intense thunderstorms surrounding the eye. The spiral bands of showers and eye/eyewall appearance look very similar to Hurricane Epsilon of 2005, which formed over waters of 75-77 F (22-23C). If Thingamabobbercane had been in the Atlantic, it would likely have been given a name and called a subtropical cyclone. The Central Pacific Hurricane Center in Honolulu isn't even mentioning it in their Tropical Weather Outlook, so Thingamabobbercane is not going to get a name. Hybrid storms of this nature are rare in the Central Pacific, and we really don't know what to do with them. It's worth noting that SSTs in the northeast Pacific are a substantial 2 C above normal; normally ocean temperatures are too cold to get hybrid subtropical storms off the coast of Oregon.
A QuikSCAT satellite pass from last night (Figure 2) shows wind speeds as high as 50 knots (57 mph) to the south of the circulation center of Thingamabobbercane. Cloud top temperatures in the "eyewall" were between -42 and -53 C, which correspond to heights of 35,000 to 40,000 feet. Satellite imagery from this morning shows that Thingamabobbercane has weakened, and resembles a donut with the bottom half missing. Wind shear, which was 15 knots yesterday, has increased to 25 knots over the storm, and is likely responsible for the weakening. Thingamabobbercane is expected to gradually weaken as it drifts northeastward over the next two days. The storm will make the transition to a regular extratropical cyclone by Saturday, and affect British Columbia with gale-force winds early next week.
Figure 2. QuikSCAT winds from 04 UTC November 2, 2006, show wind speeds as high as 50 knots (57 mph) to the south of the circulation center of Thingamabobbercane.
Thingamabobbercane is over much cooler waters than some of the late-season tropical storms of 2005--such as Vince and Epsilon--that looked similar. A drifting buoy 46637 100 miles to the north of the center is reporting SSTs of 58F (14.5C), and drifting buoy 46532 about 150 miles to the west is reporting SSTs of 62F (16.5C). Thingamabobbercane resembles the January 1995 weirdo storm that formed in the Mediterranean Sea. This unusual storm also looked like a hurricane, and formed over waters of similar temperature, 61F. Another odd hybrid storm like Thingamabobbercane formed over Lake Huron on September 14, 1996. Hurricane Huron started as a cold-cored low pressure system, then gradually acquired a warm core as it drifted over the relatively warm waters (64F, 18C) of Lake Huron. Hurricane Huron developed a cloud-free eye and spiral bands of showers and thunderstorms which brought up to four inches of rain and flooding problems to portions of Ontario and Michigan. It is the only recorded warm-core hybrid cyclone to affect the Great Lakes.
Figure 3. "Hurricane Huron" over Lake Huron closely resembles our Thingamabobbercane. Image credit: Dr. Todd Miner, Penn State University. Dr. Miner has authored an interesting techincal paper on Hurricane Huron.
For more on Thingamabobbercane
The University of Wisconsin CIMSS web site has an interesting blog with both visible and infrared Quicktime animations of the storm.
An area of disturbed weather in the Western Caribbean is associated with a tropical disturbance (93L). This disturbance has gotten less organized since yesterday, and is not expected to become a tropical depression. It will continue to bring heavy rains to Belize, the Yucatan, and Honduras over the next two days. More than two inches of rain has fallen in Cancun, Cozumel, and Belize City in the past 24 hours.
Figure 1. Preliminary model tracks for 93L in the Caribbean.
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