 Both the central dense <unk> and embedded eye pattern use the size of the <unk> . The <unk> pattern <unk> start at <unk> , equivalent to minimal tropical storm intensity ( 40 mph , 65 km / h ) . The shape of the central dense <unk> is also considered . The eye pattern utilizes the <unk> of the cloud tops within the surrounding mass of thunderstorms and contrasts it with the temperature within the eye itself . The larger the temperature difference is , the stronger the tropical cyclone . Once a pattern is identified , the storm features ( such as length and <unk> of banding features ) are further analyzed to arrive at a particular T @-@ number . The <unk> pattern indicates little development is occurring , despite the cold cloud tops associated with the quickly evolving feature . 
