How can a tropical disturbance over the Pacific grow into a typhoon powerful enough to produce winds above 150 km/h — and then begin weakening just days later? Typhoon Cempaka offers a useful real-world case study. Its rapid development in the western North Pacific during November 2026 shows how warm ocean water, rising moist air and favourable atmospheric conditions can work together to organise a powerful storm.
First, an important distinction: meteorological agencies documented Cempaka’s track and changing intensity, but those observations do not, by themselves, prove exactly which environmental factor contributed most to its strengthening. This article separates the storm’s recorded history from the general science that explains how typhoons intensify.
How powerful did Typhoon Cempaka become?
On 10 November 2026, the Hong Kong Observatory classified Cempaka as a severe typhoon and reported maximum sustained winds near its centre of 155 km/h at 8 a.m. Hong Kong time. Later that day, the U.S. National Weather Service’s Guam advisory reported maximum sustained winds of 110 mph (about 177 km/h) at 1 p.m. Chamorro Standard Time.
Why are the numbers different? Agencies may use different wind-averaging periods, observations and analysis methods. A one-minute sustained-wind estimate and a ten-minute estimate are not directly interchangeable. The safest way to report the storm is to name the agency, its observation time and its wind estimate rather than combine the figures into one supposedly exact value.
How did Cempaka develop into a typhoon?
The Hong Kong Observatory’s historical record shows Cempaka developing from a tropical depression on 6 November. It was classified as a tropical storm on 7 November, strengthened into a severe tropical storm on 8 November, became a typhoon on 9 November and reached the severe-typhoon category in the Observatory’s 10 November 8 a.m. analysis.
That progression is important: a typhoon does not appear fully formed. A broad area of thunderstorms and low pressure can gradually develop a more organised circulation. As the circulation strengthens and wind speeds rise, the system is reclassified through the stages used by the regional meteorological agency.
What gives a typhoon the energy to grow?
1. The ocean supplies heat and moisture
Warm ocean water allows more evaporation, adding water vapour to the air above the sea. When warm, humid air rises in thunderstorms and cools, some of that vapour condenses into cloud droplets. Condensation releases latent heat — energy that had been used to evaporate the water.
That heat warms the air within the storm’s central region and helps maintain the rising motion that supports a tropical cyclone. In simple terms, the ocean is not just a surface the storm travels over: it is an important source of the heat and moisture that keep the storm engine operating.
Easy example: Think about steam rising from a pot of hot water. The water supplies moisture, and the rising vapour carries it into the air. A typhoon is far more complicated, but this helps picture how the ocean can supply moisture to the atmosphere.
2. Condensation helps maintain the storm’s warm core
In a tropical cyclone, air flows towards the low-pressure centre near the surface and rises in bands of thunderstorms. As water vapour condenses, latent heat is released. This heating helps create and maintain the storm’s warm-core structure. The pressure and wind fields adjust as the circulation becomes more organised.
Moisture alone does not guarantee a powerful typhoon. The storm also needs a suitable circulation and atmospheric environment. That is why warm tropical seas can exist without a major cyclone forming over them.
3. Earth’s rotation helps organise the spin
The Coriolis effect, which results from Earth’s rotation, helps organise the rotating circulation of a tropical cyclone. In the Northern Hemisphere, the winds around a mature low-pressure cyclone rotate anticlockwise. Very close to the equator, the Coriolis effect is too weak to organise this rotation efficiently, which is one reason tropical cyclones rarely form right on the equator.
The Coriolis effect does not provide the storm’s energy. It helps organise the circulation, while the ocean-atmosphere exchange of heat and moisture provides the energy that sustains the system.
4. Wind shear can either disrupt or favour organisation
Vertical wind shear is a change in wind speed or direction with altitude. Strong shear can tilt a cyclone’s circulation and displace thunderstorms away from the centre, making it harder for the storm to stay organised. Weaker shear is generally more favourable because thunderstorms can remain closer to the centre.
Easy example: Imagine trying to keep a spinning top upright while a strong sideways force keeps pushing it. The top becomes harder to keep balanced. Strong wind shear can disturb a cyclone’s structure in a comparable way. This is an analogy, not a literal model of atmospheric motion.
Why did Cempaka strengthen — and what can we actually confirm?
The observed record confirms that Cempaka’s classification and estimated winds increased between 6 and 10 November. The science described above explains the ingredients that commonly support tropical-cyclone intensification: warm water, abundant moisture, organised rising air and an atmosphere that does not strongly disrupt the circulation.
However, the public track and intensity tables alone do not establish the exact sea-surface temperature, ocean heat content, wind-shear values or dry-air influence experienced by Cempaka throughout its development. Without a storm-specific analysis of those measurements, it would be misleading to claim that one particular factor — such as unusually warm water or exceptionally low wind shear — was proven to be the main reason Cempaka intensified.
This distinction matters. A scientifically accurate explanation should tell readers what was observed, what meteorology tells us generally, and what has not been demonstrated for this individual storm.
Why do powerful typhoons weaken?
A tropical cyclone can weaken when the environment stops supporting its organised warm-core circulation. It may move over cooler water, encounter drier air, experience stronger vertical wind shear or undergo changes in its surrounding atmospheric flow. Moving over land can also cut off its supply of ocean moisture and increase friction.
In Cempaka’s case, the U.S. National Weather Service’s 1 p.m. Chamorro Standard Time advisory on 10 November forecast that the storm would weaken through that night. The Hong Kong Observatory’s forecast issued that morning also showed a weakening trend over the following days, with the system expected to become an extratropical low by 13 November. These were forecasts at the time, not observations of what had already happened.
Where was Typhoon Cempaka heading?
At 1 p.m. Chamorro Standard Time on 10 November, the Guam National Weather Service located Cempaka near 25.3°N, 139.0°E, about 150 miles west-northwest of Iwo To. It was moving east-northeast at 15 mph (about 24 km/h). The advisory listed no watches or warnings and said it would be the final advisory issued by that office for Cempaka.
PAGASA’s 4 p.m. bulletin on 10 November placed the cyclone outside the Philippine Area of Responsibility, about 1,940 km east-northeast of extreme Northern Luzon, moving east-northeast at 35 km/h with estimated maximum sustained winds of 150 km/h and gusts up to 185 km/h. PAGASA had earlier said the cyclone was less likely to directly affect the Philippines during its forecast period. These bulletins describe conditions at their stated issue times; they should not be treated as live tracking information after that date.
Why was the storm also called Samuel?
When Cempaka entered the Philippine Area of Responsibility, PAGASA assigned it the local name Samuel. This is a regional naming practice: a tropical cyclone can have an international name used across the basin and a local name used by a national weather service. Cempaka and Samuel referred to the same cyclone, not two separate storms.
What does the name Cempaka mean?
Cempaka is a name contributed by Malaysia to the western North Pacific and South China Sea tropical cyclone naming list. It refers to the champak, a fragrant flowering tree. Names on the regional list are selected in advance through the World Meteorological Organization’s Typhoon Committee system.
Typhoon, hurricane and cyclone: are they different?
They are regional names for the same broad type of weather system: a tropical cyclone. The term typhoon is used in the western North Pacific, hurricane in the Atlantic and eastern North Pacific, and tropical cyclone in the South Pacific and Indian Ocean. The terminology changes with the ocean basin, not because the storms are fundamentally different kinds of weather system.
The science behind Cempaka, in simple terms
Cempaka’s recorded development shows how a tropical cyclone can progress from a depression to a severe typhoon over several days. The wider science explains why that can happen: warm seas supply moisture and heat, condensation releases latent heat, Earth’s rotation helps organise the circulation, and wind shear can either disrupt or favour the storm’s structure.
But no single ingredient guarantees a powerful typhoon. It is the combination of ocean conditions and atmospheric processes that matters. Cempaka also demonstrates why storm reports must be read with their timestamps: a powerful cyclone can move away from land and begin weakening, while older warnings and forecasts remain visible online.
Sources and further reading
The following official and specialist sources support the storm timeline, intensity reports, naming information and general science discussed in this article.
- Hong Kong Observatory — Tropical Cyclone Position: Cempaka historical positions and intensity record, 6–10 November 2026
- U.S. National Weather Service, Guam — Typhoon Cempaka Advisory No. 16, 10 November 2026
- PAGASA — Tropical Cyclone Bulletin archive for Typhoon Samuel (Cempaka), November 2026
- NOAA JetStream — Tropical cyclones: how they form and develop
- National Hurricane Center — Saffir-Simpson Hurricane Wind Scale and wind terminology
Accuracy note: Storm positions, wind speeds and forecasts are tied to the date and time of each agency bulletin. Different agencies may report different sustained-wind estimates because their averaging periods and analysis methods differ. This article does not attribute Cempaka’s intensification to a specific ocean or atmospheric factor unless supported by storm-specific analysis.