CSU Lowers Hurricane Forecast

Colorado State University Lowers 2009 Hurricane Forecast for Atlantic basin to “Slightly Below Average Season”

The forecasters  now anticipates 11 named storms forming during the official Atlantic basin hurricane season between June 1 and November 30.

William Gray and Phil Klotzbach. The Colorado State University Tropical Storm Duo!

CSU forecasts use available data on global oceanic and atmospheric conditions [El Nino, sea surface temperatures, sea level pressures … ] recorded prior to the past seasons and compare the results to forecast future trends.

“The probability of a major hurricane making landfall along the U.S. coastline is 48 percent compared with the last-century average of 52 percent,” said lead forecaster Phil Klotzbach.

“Currently observed climate factors are similar to conditions that occurred during 1959, 1960, 1965, 2001 and 2002 seasons. The average of these five seasons had slightly below-average activity, and Klotzbach and Gray predict the 2009 season will have activity in line with the average of these five years.” CSU forecasters reported.

According to CSU forecast tropical cyclone activity in 2009 will be 90 percent of the average season. In 2008 tropical cyclone activity reached about 160 percent of the average.

CSU Hurricane Forecasters said they will issue a final seasonal update on Tuesday, August 4, 2009

Here’s summary of their revised forecast released June 2, 2009

EXTENDED RANGE ATLANTIC BASIN HURRICANE FORECAST FOR 2009

Tropical Cyclone Parameters Extended Range

• Named Storms:  (9.6)* 11
• Named Storm Days: (49.1) 50
• Hurricanes:  (5.9) 5
• Hurricane Days (24.5) 20
• Intense Hurricanes: (2.3) 2
• Intense Hurricane Days:  (5.0) 4
• Accumulated Cyclone Energy:  (96) 85
• Net Tropical Cyclone Activity (100%) 90

{Note: Numbers in ( ) represent average year data based on 1950-2000 records.

On the face of it, their revised forecast appears to be  sensible; however, it excludes the possibility that the traditional hurricane season might be shifting.

Related Links:

• FEWW FORECAST: 2009 Likely Wettest Year on Record
• What if each time a storm struck your area it turned out to be a major hurricane?
• 2009 Hurricane Season: Storms in Teacup, or Nasty Surprises?

CSU forecasters’ Landfall Probability tables are available at  http://www.e-transit.org/hurricane

FEWW New Hurricane Scale

FEWW New Hurricane Scale Makes Hurricane Classification More Meaningful!

FEWW’s New Hurricane Scale is based on the Saffir-Simpson Hurricane Scale and provides a more detailed definition of hurricane forces.

Size Description

To make the classification of tropical cyclones even more descriptive, FIRE-EARTH recommends the addition of following suffixes for storm size to denote the category:

• Midget hurricanes (m). With the average radius from the storm’s center of circulation to its outermost closed isobar (ROCI) in four quadrants measuring less than two degrees of latitude [222.2 km or 138.1 miles.]

• Small. Small Hurricanes (s).  ROCI measuring between 2 and 3 degrees of latitude [222km< ROCI< 333km]
• Regular. Average Hurricanes (r). ROCI measuring between 3 and 6 degrees of latitude [333km< ROCI< 667km]
• Large. Large Hurricanes (g). ROCI of between 6 and 8 degrees of latitude [667km< ROCI< 889km]
• Monster. Very Large Hurricanes (x). ROCI of larger than 8 degrees of latitude [ROCI> 889km]

Example: Hurricane GRETA, with ROCI of 960km, the largest ever recorded Atlantic hurricane, which reached a maximum sustained winds of about 225km/h on November 5, 1956 may be represented as a Monster hurricane, or 4Ax category hurricane on the FEWW New Hurricane Scale.

Tropical Cyclones

What’s a Tropical cyclone?

A tropical cyclone is a storm system characterized by a low pressure center and numerous thunderstorms that produce strong winds and flooding rain. A tropical cyclone feeds on the heat released when moist air rises and the water vapor it contains condenses.

The term “tropical” refers to both the geographic origin of these systems, which form almost exclusively in tropical regions of the globe, and their formation in Maritime Tropical air masses. The term “cyclone” refers to such storms’ cyclonic nature, with counterclockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on their location and strength, tropical cyclones are referred to by other names, such as hurricane, typhoon, tropical storm, cyclonic storm, tropical depression and simply cyclone.

Map of the cumulative tracks of all tropical cyclones during the 1985–2005 time period.

Tropical cyclones can produce extremely powerful winds and torrential rain, as well as high waves and devastating storm surge. They develop over large bodies of warm water, and can cause significant damage to coastal regions flooding up to 40km from the coastline. Although inland regions are relatively safe from receiving strong winds, heavy rains can produce significant flooding inland. (Source)

Cyclones can relieve drought conditions

Known for devastating human populations, tropical cyclones can also relieve drought conditions. They also carry heat and energy away from the tropics and transport it towards temperate latitudes, which makes them an important part of the global atmospheric circulation mechanism. As a result, tropical cyclones help to maintain equilibrium in the Earth’s troposphere, and to maintain a relatively stable and warm temperature worldwide. (Source)

Structure of a tropical cyclone (Source: NOAA)

Cyclone Structure

Tropical cyclones are areas of low atmospheric pressure near the Earth’s surface. The pressures recorded at the centers of tropical cyclones are very low. Tropical cyclones are driven by the release of large amounts of latent heat of condensation, which occurs when moist air is carried upwards and its water vapor condenses.

Eye and inner core

A strong tropical cyclone will harbor an area of sinking air at the center of circulation. If this area is strong enough, it can develop into an eye. Weather in the eye is normally calm and free of clouds, although the sea may be extremely violent. The eye is normally circular in shape, and may range in size from 3 km to 370km in diameter. (Source)

Brief History:

The 1970 Bhola cyclone is the deadliest tropical cyclone on record, killing more than 300,000 people and potentially as many as 1 million after striking the densely populated Ganges Delta region of Bangladesh on November 13, 1970. Its powerful storm surge was responsible for the high death toll. The North Indian cyclone basin has historically been the deadliest basin, with several cyclones since 1900 killing more than 100,000 people, all in Bangladesh. Super Typhoon Nina caused major damage and deaths in China, mainly from the collapse of the Banqiao Dam. Hundreds of thousands of people died due to the resulting floods, making it one of the deadliest tropical cyclones recorded in history. The collapse of the dam due to heavy floods also caused a string of 60 or so smaller dams to collapse. (Source)

Global Warming and Hurricanes

Source: Geophysical Fluid Dynamics Laboratory

The strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth’s climate is warmed by increasing levels of greenhouse gases in the atmosphere. […]
According to a new simulation study by a group of scientists at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL), a 5-12% increase in wind speeds for the strongest hurricanes (typhoons) in the northwest tropical Pacific is projected if tropical sea surfaces warm by a little over 2°C (Figure 1). Recent preliminary findings indicate that these results may apply to the other tropical cyclone basins as well. […] (Source: OAR NOAA)

Recent Cyclones and Hurricanes:

• The most intense tropical cyclone ever recorded (watch this space for the record breakers!)
  
• List of notable tropical cyclones
• List of Atlantic hurricanes
• List of Pacific hurricanes
• List of tropical cyclones

• ist of Atlantic hurricane seasons (2008 season)
• List of Pacific hurricane seasons (2008 season)
• List of Pacific typhoon seasons (2008 season)
• List of North Indian Ocean cyclone seasons ( 2008 season)
• List of Southern Hemisphere cyclone seasons (2007-08 Southern Hemisphere)