The P-3 airplane allows scientists to fly right into a storm, to learn more about its intensity than they could by just relying on satellites. The scientists use onboard instruments to measure the storm's wind strength and turbulence as well as conditions on the ocean's surface. Some of the instrumentation includes nose, belly, and tail radar (look at precipitation), microwave (ocean surface conditions), and expendable probes (dropsondes for measuring the atmosphere and AXBTs for measuring the ocean's top surface layer).
Dropsondes are released from the airplane to gather real-time data from right inside the storm. The dropsondes fall through the storm on a parachute, sending back data about pressure, humidity, temperature, and wind speed and direction.
For more information, please visit:
NOAA - AOC Instrumentation Information
NOAA – AOC P3 Aircraft Information
NOAA - What is an XBT?