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