Weather reconnaissance aircraft report several types of observations. Below you will find a brief description of each observation type (click on the name to see a detailed explanation and an example).

Vortex Data Message (or with frames) Summarizes hurricane data, to include the location of the eye (the "fix"), the minimum central pressure, maximum winds on the way into the eye, temperature inside and outside of the eye, etc.

Supplementary Vortex Data Message. Profiles the flight-level data during one pass through the eye. Each line of weather data is spaced 15 nautical miles (nm) apart, usually from 105 nm out (7 times 15!), into the center, then out the other side for another 105 nm.

Dropsonde Message. On most passes through the eye (fixes) at 10,000 feet, a dropsonde instrument is dropped at the exact center and sometimes in the eyewall. It measures a vertical profile of the atmosphere similar to a weather balloon (rawinsonde), except it goes down instead of up! This is how we measure the sea-level pressure. Dropsondes are also released every 400 nm enroute to and from the storm and on training flights.

Recco Observation. A line of weather data observed by the weather officer, usually every 30 minutes enroute, and at the turnpoints in the storm. Typically, only the first eight groups are encoded, but on rare occasions clouds, icing, radar and surface winds are included.

High Density Observations. These are collected automatically by the on-board computer, usually every minute (about three nm apart), but may be collected in 30- second or two-minute intervals. They are sent directly to the National Hurricane Center (NHC) by satellite communications in blocks of 20 lines of data. Due to the voluminous nature of these observations, they are not disseminated to the public, but are used on a real-time basis by the hurricane specialists at NHC.