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NOAA Office of Satellite and Product Operations

Dvorak Current Intensity Chart

 

CI
Number
MWS
Knots
MWS
MPH
MSLP
Atlantic
MSLP
NW Pacific
Saffir-Simpson Category
(Approximate)
   1 25 KTS 29 MPH      
1.5 25 KTS 29 MPH      
   2 30 KTS 35 MPH 1009 mb 1000 mb  
2.5 35 KTS 40 MPH 1005 mb 997 mb  
   3 45 KTS 52 MPH 1000 mb 991 mb  
3.5 55 KTS 63 MPH 994 mb 984 mb 1:  (64-83 KTS)
    4 65 KTS 75 MPH 987 mb 976 mb 1:  (64-83 KTS)
4.5 77 KTS 89 MPH 979 mb 966 mb 1:  (64-83 KTS);  2:  (84-96 KTS)
    5 90 KTS 104 MPH 970 mb 954 mb 2:  (84-96 KTS);  3:  (96-112 KTS)
5.5 102 KTS 117 MPH 960 mb 941 mb 3:  (96-112 KTS)
    6 115 KTS 132 MPH 948 mb 927 mb 4:  (113-136 KTS)
6.5 127 KTS 146 MPH 935 mb 914 mb 4:  (113-136 KTS)
    7 140 KTS 161 MPH 921 mb 898 mb 5:  (137+ KTS)
7.5 155 KTS 178 MPH 906 mb 879 mb 5:  (137+ KTS)
    8 170 KTS 196 MPH 890 mb 858 mb 5:  (137+ KTS)

Where:
CI -- Current Intensity
MWS -- Mean Wind Speed
MSLP -- Mean Sea Level Atmospheric Pressure in Millibars

Saffir-Simpson Hurricane Categories
Hurricane:
Category 1: 74-95 mph (64-82 kt, 119-153 km/h)
Category 2: 96-110 mph (83-95 kt, 154-177 km/h)

Major Hurricane:
Category 3: 111-129 mph (96-112 kt, 178-208 km/h)
Category 4: 130-156 mph (113-136 kt, 209-251 km/h)
Category 5: 157 mph or higher (137 kt or higher, 252 km/h or higher)

More Information about the Saffir-Simpson Hurricane Categories