This is storm CLARA that was active in 1964 in the W. Pacific region with maximum winds of 148 km/h.

What was the maximum intensity of the storm?

Max Wind: 148 km/h. Min Pressure: hPa.

storm CLARA (1964) - Track and intensity details

Name: storm CLARA
Start: 1964-10-01
End: 1964-10-08
Location: W. Pacific

CLARA (1964)

Storm Code: 1964276N07142 | Region: W. Pacific
Active from 01/10/1964 to 09/10/1964 (8 days)

148 km/h

1-min Wind (JTWC)

Level 13

143 km/h

10-min Wind (CMA)

Level 13

975 hPa

Min Pressure

4,557 km

Distance

Forecast Agencies

Agency	Max Intensity	Trajectory	Energy	highest_classification
WMO (International) (coordinates_only)	~	980	30	4,489	~	~	Undefined
JMA (Japan) (coordinates_only)	~	980	59	4,557	~	~	Undefined
CMA (China)	143	975	55	4,268	66.61	84.80	Level 13 - Violent Storm
JTWC	148	~	51	3,922	66.92	87.02	Level 13 - Violent Storm
HKO (Hong Kong)	130	975	51	3,975	54.30	64.98	Level 12 - Violent Storm
DS824	148	~	51	3,922	66.92	87.02	Level 13 - Violent Storm
TD9636	148	~	49	3,786	67.67	88.29	Level 13 - Violent Storm
TD9635	148	982	51	4,013	66.92	87.02	Level 13 - Violent Storm

Agency

Max Intensity

Trajectory

Energy

highest_classification

Max Wind (km/h)

Min Pressure (hPa)

Number of points

Distance (km)

ACE (10⁴ (km/h)²)

PDI (10⁶ (km/h)³)

WMO (International)
(coordinates_only)

980

4,489

Undefined

JMA (Japan)
(coordinates_only)

980

4,557

Undefined

CMA (China)

143

975

4,268

66.61

84.80

Level 13 - Violent Storm

JTWC

148

3,922

66.92

87.02

Level 13 - Violent Storm

HKO (Hong Kong)

130

975

3,975

54.30

64.98

Level 12 - Violent Storm

DS824

148

3,922

66.92

87.02

Level 13 - Violent Storm

TD9636

148

3,786

67.67

88.29

Level 13 - Violent Storm

TD9635

148

982

4,013

66.92

87.02

Level 13 - Violent Storm

Advanced Meteorological Indices by Agency Automatically calculated from raw data

WMO (International)

Pressure Variation
Max Pressure Drop/Step	-6 hPa
Max Pressure Drop/24h	-12 hPa
Max Pressure Rise/Step (weakening)	+10 hPa
Movement & Duration
Avg Movement Speed	25.8
Tracking Time	174h (7.3 days)
Peak Intensity & Range
Latitude	7°N – 18.2°N (11.2°)
Longitude	103.3°E – 142°E (38.7°)

JMA (Japan)

Pressure Variation
Max Pressure Drop/Step	-3 hPa
Max Pressure Drop/24h	-10 hPa
Max Pressure Rise/Step (weakening)	+5 hPa
Movement & Duration
Avg Movement Speed	26.2
Tracking Time	174h (7.3 days)
Peak Intensity & Range
Latitude	7°N – 18°N (11°)
Longitude	103.3°E – 142°E (38.7°)

CMA (China) RI

Energy
ACE (10⁴ (km/h)²)	66.61	Very High
PDI (10⁶ (km/h)³)	84.80
Intensification / Weakening
Max Wind Gain/Step	+19 km/h
Max Wind Gain/24h	+56 km/h	RI
Max Wind Loss/Step	-19 km/h
Pressure Variation
Max Pressure Drop/Step	-3 hPa
Max Pressure Drop/24h	-10 hPa
Max Pressure Rise/Step (weakening)	+5 hPa
Movement & Duration
Avg Movement Speed	26.3 km/h
Tracking Time	162h (6.8 days)
Time as TD+ (≥34kt)	288h (12d)
Time as Storm+ (≥64kt)	162h (6.8d)
Peak Intensity & Range
Peak Intensity	08:00 06/10/1964 17.2°N, 116.4°E
Latitude	7°N – 18.1°N (11.1°)
Longitude	105.7°E – 142°E (36.3°)

JTWC

Energy
ACE (10⁴ (km/h)²)	66.92	Very High
PDI (10⁶ (km/h)³)	87.02
Intensification / Weakening
Max Wind Gain/Step	+9 km/h
Max Wind Gain/24h	+37 km/h	Fast
Max Wind Loss/Step	-24 km/h
Movement & Duration
Avg Movement Speed	26.1 km/h
Tracking Time	150h (6.3 days)
Time as TD+ (≥34kt)	270h (11.3d)
Time as Storm+ (≥64kt)	186h (7.8d)
Peak Intensity & Range
Peak Intensity	08:00 05/10/1964 16.3°N, 122.2°E
Latitude	8.7°N – 18.5°N (9.8°)
Longitude	104.9°E – 138.8°E (33.9°)

HKO (Hong Kong)

Energy
ACE (10⁴ (km/h)²)	54.30	Very High
PDI (10⁶ (km/h)³)	64.98
Intensification / Weakening
Max Wind Gain/Step	+15 km/h
Max Wind Gain/24h	+46 km/h	Fast
Max Wind Loss/Step	-24 km/h
Pressure Variation
Max Pressure Drop/Step	-4 hPa
Max Pressure Drop/24h	-10 hPa
Max Pressure Rise/Step (weakening)	+5 hPa
Movement & Duration
Avg Movement Speed	26.5 km/h
Tracking Time	150h (6.3 days)
Time as TD+ (≥34kt)	246h (10.3d)
Time as Storm+ (≥64kt)	186h (7.8d)
Peak Intensity & Range
Peak Intensity	08:00 05/10/1964 16.5°N, 121.9°E
Latitude	8.7°N – 17.8°N (9.1°)
Longitude	104.2°E – 138.8°E (34.6°)

DS824

Energy
ACE (10⁴ (km/h)²)	66.92	Very High
PDI (10⁶ (km/h)³)	87.02
Intensification / Weakening
Max Wind Gain/Step	+9 km/h
Max Wind Gain/24h	+37 km/h	Fast
Max Wind Loss/Step	-24 km/h
Movement & Duration
Avg Movement Speed	26.1 km/h
Tracking Time	150h (6.3 days)
Time as TD+ (≥34kt)	270h (11.3d)
Time as Storm+ (≥64kt)	186h (7.8d)
Peak Intensity & Range
Peak Intensity	08:00 05/10/1964 16.3°N, 122.2°E
Latitude	8.7°N – 18.5°N (9.8°)
Longitude	104.9°E – 138.8°E (33.9°)

TD9636

Energy
ACE (10⁴ (km/h)²)	67.67	Very High
PDI (10⁶ (km/h)³)	88.29
Intensification / Weakening
Max Wind Gain/Step	+9 km/h
Max Wind Gain/24h	+37 km/h	Fast
Max Wind Loss/Step	-17 km/h
Movement & Duration
Avg Movement Speed	26.3 km/h
Tracking Time	144h (6 days)
Time as TD+ (≥34kt)	270h (11.3d)
Time as Storm+ (≥64kt)	180h (7.5d)
Peak Intensity & Range
Peak Intensity	08:00 05/10/1964 16.3°N, 122.2°E
Latitude	8.7°N – 18.4°N (9.7°)
Longitude	106.1°E – 138.8°E (32.7°)

TD9635

Energy
ACE (10⁴ (km/h)²)	66.92	Very High
PDI (10⁶ (km/h)³)	87.02
Intensification / Weakening
Max Wind Gain/Step	+9 km/h
Max Wind Gain/24h	+37 km/h	Fast
Max Wind Loss/Step	-24 km/h
Pressure Variation
Max Pressure Drop/Step	-4 hPa
Max Pressure Drop/24h	-8 hPa
Max Pressure Rise/Step (weakening)	+2 hPa
Movement & Duration
Avg Movement Speed	26.8 km/h
Tracking Time	150h (6.3 days)
Time as TD+ (≥34kt)	270h (11.3d)
Time as Storm+ (≥64kt)	186h (7.8d)
Peak Intensity & Range
Peak Intensity	08:00 05/10/1964 16.3°N, 122.2°E
Latitude	8.2°N – 18.5°N (10.3°)
Longitude	104.9°E – 138.8°E (33.9°)

Advanced Indices Legend

ACE: Accumulated Cyclone Energy - measures total storm activity

PDI: Power Dissipation Index - measures potential destructiveness

RI: Rapid Intensification - when wind increases >=30 kt/24h or pressure drops >=30 hPa/24h

Countries with Direct Landfall

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Index	Meaning	Formula / Condition	Classification
ACE Accumulated Cyclone Energy	Accumulated Cyclone Energy. Measures the total energy generated by the storm during its lifetime. Only counts reports with wind ≥ 35 kt (TS level or higher).	`ACE = Σ(V_max²) / 10&sup4;` Unit: 10⁴ kt²	< 2: Low 2-6: Medium 6-15: High ≥ 15: Very High
PDI Power Dissipation Index	Power Dissipation Index. More sensitive than ACE to extremely strong storms due to using cubic power. Reflects potential destructive power.	`PDI = Σ(V_max&sup³;) / 10&sup6;` Unit: 10⁶ kt³	Higher value = greater cumulative destructive power
RI Rapid Intensification	Rapid Intensification - storm strengthens suddenly in a short time. Very dangerous as it is difficult to forecast and causes surprise for prevention efforts.	Wind increase ≥ 30 kt/24h or Pressure drop ≥ 30 hPa/24h	Has RI or Fast increase (≥20kt)
Max wind gain/step	Maximum wind increase between 2 consecutive reports (usually 6 hours apart). Shows the fastest local intensification rate.	`max(V_i+1 - V_i)` Unit: kt (km/h)	Positive value = storm strengthening
Max wind gain/24h	Maximum wind increase in a 24-hour window. Main criterion for determining Rapid Intensification (RI).	`max(V_t+24h - V_t)` RI if ≥ 30 kt/24h	≥ 30kt: RI ≥ 20kt: Fast
Max wind loss/step	Maximum wind weakening between 2 consecutive reports. Shows at which stage the storm weakened fastest.	`max(V_i - V_i+1)` Unit: kt (km/h)	Positive value = storm weakening
Max pressure drop/step	Maximum pressure drop between 2 consecutive reports. Pressure decrease = storm center strengthening. Reflects local deepening rate.	`max(P_i - P_i+1)` Unit: hPa	Higher value = faster strengthening
Max pressure drop/24h	Maximum pressure drop in a 24-hour window. Important index for evaluating explosive deepening / explosive intensification.	`max(P_t - P_t+24h)` Explosive if ≥ 30 hPa	≥ 30hPa: RI ≥ 20hPa: Strong
Max pressure rise/step	Maximum pressure rise between 2 consecutive reports. Pressure increase = storm weakening. Large value indicates rapid weakening (due to terrain interaction, landfall, etc.).	`max(P_i+1 - P_i)` Unit: hPa	Higher value = faster weakening
Average moving speed	Average moving speed of the storm center during the entire monitoring period by that agency.	`V_avg = S_total / T_total` Unit: kt (km/h)	Slow-moving storms (<15 km/h) usually cause prolonged heavy rain
Monitoring duration	Total time from first report to last report of that agency.	`T = t_end - t_start` Unit: hours (days)	Different agencies may monitor for different durations
TS+ Duration	Total hours with average wind ≥ 34 kt (Tropical Storm level or higher). Reflects how long the storm maintained significant intensity.	Average wind ≥ 34 kt	Longer storm = greater total damage
TY+ Duration	Total hours with average wind ≥ 64 kt (Typhoon level or higher). Storms maintaining this level longer have much greater destructive power.	Average wind ≥ 64 kt	Longer time at Typhoon level = more dangerous
Peak Intensity	Time and location (lat, lon) when the storm reached maximum wind according to each agency. Helps identify where the storm was strongest.	V_max = max(V_i)	Peak location helps assess danger for nearby areas
Latitude / Longitude	Spatial range of activity by latitude and longitude. Shows whether the storm affected area is wide or narrow.	min-max(lat), min-max(lon)	Large range = long trajectory, wide impact

Index

Meaning

Formula / Condition

Classification

ACE
Accumulated Cyclone Energy

Accumulated Cyclone Energy. Measures the total energy generated by the storm during its lifetime. Only counts reports with wind ≥ 35 kt (TS level or higher).

ACE = Σ(V_max²) / 10&sup4;
Unit: 10⁴ kt²

< 2: Low
2-6: Medium
6-15: High
≥ 15: Very High

PDI
Power Dissipation Index

Power Dissipation Index. More sensitive than ACE to extremely strong storms due to using cubic power. Reflects potential destructive power.

PDI = Σ(V_max&sup³;) / 10&sup6;
Unit: 10⁶ kt³

Higher value = greater cumulative destructive power

RI
Rapid Intensification

Rapid Intensification - storm strengthens suddenly in a short time. Very dangerous as it is difficult to forecast and causes surprise for prevention efforts.

Wind increase ≥ 30 kt/24h or Pressure drop ≥ 30 hPa/24h

Has RI or
Fast increase (≥20kt)

Max wind gain/step

Maximum wind increase between 2 consecutive reports (usually 6 hours apart). Shows the fastest local intensification rate.

max(V_i+1 - V_i)
Unit: kt (km/h)

Positive value = storm strengthening

Max wind gain/24h

Maximum wind increase in a 24-hour window. Main criterion for determining Rapid Intensification (RI).

max(V_t+24h - V_t)
RI if ≥ 30 kt/24h

≥ 30kt: RI
≥ 20kt: Fast

Max wind loss/step

Maximum wind weakening between 2 consecutive reports. Shows at which stage the storm weakened fastest.

max(V_i - V_i+1)
Unit: kt (km/h)

Positive value = storm weakening

Max pressure drop/step

Maximum pressure drop between 2 consecutive reports. Pressure decrease = storm center strengthening. Reflects local deepening rate.

max(P_i - P_i+1)
Unit: hPa

Higher value = faster strengthening

Max pressure drop/24h

Maximum pressure drop in a 24-hour window. Important index for evaluating explosive deepening / explosive intensification.

max(P_t - P_t+24h)
Explosive if ≥ 30 hPa

≥ 30hPa: RI
≥ 20hPa: Strong

Max pressure rise/step

Maximum pressure rise between 2 consecutive reports. Pressure increase = storm weakening. Large value indicates rapid weakening (due to terrain interaction, landfall, etc.).

max(P_i+1 - P_i)
Unit: hPa

Higher value = faster weakening

Average moving speed

Average moving speed of the storm center during the entire monitoring period by that agency.

V_avg = S_total / T_total
Unit: kt (km/h)

Slow-moving storms (<15 km/h) usually cause prolonged heavy rain

Monitoring duration

Total time from first report to last report of that agency.

T = t_end - t_start
Unit: hours (days)

Different agencies may monitor for different durations

TS+ Duration

Total hours with average wind ≥ 34 kt (Tropical Storm level or higher). Reflects how long the storm maintained significant intensity.

Average wind ≥ 34 kt

Longer storm = greater total damage

TY+ Duration

Total hours with average wind ≥ 64 kt (Typhoon level or higher). Storms maintaining this level longer have much greater destructive power.

Average wind ≥ 64 kt

Longer time at Typhoon level = more dangerous

Peak Intensity

Time and location (lat, lon) when the storm reached maximum wind according to each agency. Helps identify where the storm was strongest.

V_max = max(V_i)

Peak location helps assess danger for nearby areas

Latitude / Longitude

Spatial range of activity by latitude and longitude. Shows whether the storm affected area is wide or narrow.

min-max(lat), min-max(lon)

Large range = long trajectory, wide impact

CLARA (1964)

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Advanced Meteorological Indices by Agency Automatically calculated from raw data

Advanced Indices Legend

Countries with Direct Landfall

CLARA

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CLARA (1964)

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Weather Agencies (8 sources)

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Indices Legend

Advanced Meteorological Indices by Agency Automatically calculated from raw data

Advanced Indices Legend

Countries with Direct Landfall

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