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Igor spares Bermuda; Fanapi hits China; exceptionally quiet in the Pacific

By: Dr. Jeff Masters, 1:29 PM GMT on September 20, 2010

The core of Category 1 Hurricane Igor passed approximately 40 miles west of Bermuda at 11 pm AST last night, bringing winds just below hurricane force to the island. Winds at the Bermuda Airport peaked at 68 mph, gusting to 93 mph, at 11:22 pm AST last night. Tropical storm force winds of 39 mph began at 10 am AST on Sunday, and were still present as of 9:38 am AST (44 mph, gusting to 53 mph.) Bermuda radar shows that the core of Igor is now well past Bermuda, with only a few spiral bands to the south that will bring occasional rain squalls to the island this morning. Pressures are rising rapidly, and the storm is almost over for Bermuda. No injuries or major damage has been reported from Bermuda thus far, though Igor's waves are being blamed for two deaths in the Caribbean, one on Puerto Rico and one on St. Croix.

Igor is headed northeastward, out to sea, but will pass close enough to southeast Newfoundland to bring tropical storm force winds there on Tuesday night. Rainfall amounts of 3 - 5 inches are possible for the capital of St. Johns.

Figure 1. The eye of Hurricane Igor as seen by the International Space Station at 9:56 am EDT September 14, 2010. At the time, Igor was a Category 4 hurricane with 135 mph winds. This image ranks as one of the top-five most spectacular hurricane images ever taken from space, in my mind. To see the full-size image, visit the NASA Earth Observatory web site.

A tropical wave (Invest 94L) off the coast of Africa, a few hundred miles west of the Cape Verdes Islands, has developed a well-defined surface circulation and is threat to develop into a tropical depression. The wave is under a low 5 - 10 knots of wind shear, and is over warm 28°C waters. Dry air from the Sahara is interfering with development, and downdrafts created by mid-level dry air getting ingested into the storm are creating surface arc clouds on the west side of the storm, as seen in recent visible satellite loops. 94L only has a modest amount of heavy thunderstorm activity associated with it, and the amount of thunderstorm activity will have to increase in order for this system to be considered a tropical depression. Shear is expected to be low for the next four days, and most of the major forecast models develop 94L into a tropical depression 1 - 4 days from now. NHC is giving the wave a 80% of developing into a tropical depression by Wednesday.

Figure 2. Morning satellite image of Invest 94L.

Tropical Storm Julia is being ripped apart by wind shear from Igor, and will likely dissipate on Tuesday.

Typhoon Fanapi hits China
Typhoon Fanapi made landfall in mainland China about 150 miles east-northeast of Hong Kong this morning as a Category 1 storm with 75 mph winds. Fanapi was the strongest typhoon so far this season, peaking at Category 3 strength with 120 mph winds shortly before weakening to a Category 2 storm with 105 mph winds when it hit northern Taiwan early Sunday morning, local time. Fanapi killed three people on the island, and brought rains of up to 1400 mm (4.6 feet) to mountainous regions in the interior. Taipei 101, the second tallest building in the world with more than 100 stories, reportedly swayed some 15 cm in Fanapi's winds.

A remarkably quiet Western Pacific typhoon season and Eastern Pacific hurricane season
It has been an exceptionally quiet Western Pacific typhoon season. Before Fanapi, the strongest typhoon this season was Typhoon Kompasu, a low-end Category 3 storm with 115 mph winds that hit South Korea in early September. According to statistics forwarded to me by NOAA meteorologist Paul Stanko on Guam, by this point in an ordinary typhoon season, we should have had 17 named storms, 11 typhoons, and 2 super supertyphoons (winds of 150+ mph.) This year, we've had just 11 named storms, 5 typhoons, and no supertyphoons. The record low for a typhoon season was 18 named storms (set in 1998), 9 typhoons (set in 1998), and no supertyphoons (set in 1974.) We have a chance of beating all of these records this year. The peak date for the Western Pacific typhoon season is August 28, so we are well past the peak.

It's a similar story out in the Eastern Pacific, where a near-record quiet hurricane season is occurring. So far there have been 6 named storms, 3 hurricanes, and 2 intense hurricanes. Ordinarily, we should have had 12 named storms, 6 hurricanes, and 2 intense hurricane by this point in the season. Since reliable satellite records of Eastern Pacific hurricane activity began in 1970, the quietest season on record was 1977, when just 8 named storms occurred. The fewest hurricanes occurred in 2007 (four), and there have been two years with no intense hurricanes. The peak of Eastern Pacific hurricane season is around August 25, and on average we can expect just 3 more named storms this year. Thus, we could set records for the fewest named storms and hurricanes this year.

Figure 3. Typhoon Fanapi at landfall in China at 5:15 UTC on September 20, 2010. Image credit: NASA.

Elsewhere in the tropics
The NOGAPS, ECMWF, and GFS models have been predicting development of a strong tropical disturbance or tropical depression in the Central Caribbean 6 - 9 days from now. However, the timing, location, and track of the potential development have been inconsistent from run to run. We should merely take note of the fact that these models predict that the Caribbean will be ripe for tropical storm development late this week and early next week, and not put much faith in the specifics of these highly unreliable long-range forecasts.

I'll have a new post on Tuesday morning.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.