As of June 1, the 2011 Atlantic hurricane season is in progress. The first TCPOD (Tropical Cyclone Plan Of the Day) was issued yesterday. In fact, it did order investigation of an area of interest in the Gulf of Mexico. This daily product is available from NOAA's NHC Aircraft Reconnaissance page, which is here:
http://www.nhc.noaa.gov/reconlist.shtml
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Hurricane Hunters are US Air Force Reserve personnel who fly specially outfitted WC-130J aircraft on long missions which make repeated passes through tropical disturbances at 10,000 feet while returning weather and position data to the National Hurricane Center in Florida. The radio call sign is TEAL.
In hurricanes, they fly cross-shaped patterns that pass through the eye, where they drop a weather instrument called a dropsonde. This parachutes down to the sea, transmitting the whole time while the sonde operator records its data.
This mission began in 1944, but it still provides essential ground truth that has been shown to increase the accuracy of hurricane forecasting.
NOAA also flies some aircraft reconnaissance missions, in various types of aircraft depending on altitude.
Flights increase in large hurricanes that may threaten land, when more frequent fixes are needed.