Editing 53rd Weather Reconnaissance Squadron (section)

===Tropical cyclone operational profiles===
When a tropical disturbance becomes suspect for development as a tropical or subtropical cyclone, the NHC assigns the system a [[Invest (meteorology)|temporary tracking ("Investigation") number]]{{efn|Numbers 90 through 99 in the cyclone numbering system are reserved for such disturbances. Although not required, the "90" series of cyclone numbers is assigned sequentially and normally reused throughout the calendar year. The number is further modified by a two-letter ocean basin code. Investigation AL97 (or "97L" in verbal shorthand) would be the seventh sequential disturbance in the North Atlantic basin, while Invest. EP92 (92E) is the second in the East Pacific basin north of the equator.}} and requests the 53rd WRS to determine if the winds are blowing in a counterclockwise rotation, indicating a "closed [[Cyclone#Structure|cyclonic circulation]]". This investigative mission is flown at an altitude of {{convert|500|–|1500|ft|abbr=on}} above the ocean surface in a pattern designated by the ARWO aboard the mission WC-130 based on observed conditions.{{efn|"Suggested" investigative patterns are the X, Box, and Delta patterns, described and illustrated at ''NHOP 2015'', pages 5–19 and 5–20.}} The ARWO, using a [[microwave radiometer|stepped-frequency microwave radiometer]] (SFMR, or "smurf"),<ref name="hss"/><ref name="smrf">{{cite web| url= https://www.403wg.afrc.af.mil/About/Fact-Sheets/Display/Article/192532/hurricane-hunter-weather-equipment/|title = Stepped-Frequency Microwave Radiometer fact Sheet| publisher = 403rd Wing AFRC| access-date= 12 December 2012}}</ref>{{efn|The SFMR is designed to continuously measure surface winds directly below the WC-130J, and is installed on the aircraft within a wing-mounted antenna pod. As the plane flies through a storm, the SFMR senses microwave radiation naturally emitted from foam created on the sea by winds at the surface. Computers determine wind speeds based on the levels of microwave radiation detected, extrapolated from the winds at the aircraft's altitude or from a dropsonde released from the aircraft. The SFMR can also determine rainfall rates within a system, which in addition to wind speeds at flight level, provides structural detail of the storm.}} continuously monitors ocean waves to determine wind speed and direction. The low-level wind and pressure fields provide an accurate picture for NHC forecasters. Investigative missions are usually flown during daylight and may be timed to arrive in the investigative area at first light in the morning or last light in the evening. Weak pressure gradients, large areas of calm, and light winds in areas of heavy convective activity often make vortex fixes difficult to obtain in areas of weak circulation, challenging the skills of the crews.

Once NHC determines that there is circulation within the disturbance, the mission becomes a sequentially numbered "fix" mission, conducted initially every six hours by rotating flights in cooperation with NOAA missions, and then at three-hour intervals as the storm moves within specified parameters.<ref name="53wrsmp">{{cite web | url= http://www.hurricanehunters.com/mission.html|title = The Mission of the Hurricane Hunters| publisher = Hurricane Hunters Association.com| access-date=30 August 2010| archive-url= https://web.archive.org/web/20100826005613/http://www.hurricanehunters.com/mission.html| archive-date= 26 August 2010 | url-status= live}}</ref>{{efn|A typical weather reconnaissance Tropical Cyclone Plan of the Day (TCPOD) is reproduced [http://www.nhc.noaa.gov/text/MIAREPRPD.shtml here]. Up to four 6-hour fixes per day are conducted when a system is within 500 nautical miles of landfall and west of 55°W in the Atlantic, and up to eight 3-hour fixes per day if within 300 nautical miles of the coast of the United States, Hawaii, Puerto Rico, the Virgin islands, or DOD installations. Up to two "synoptic surveillance" missions per day may be flown on the periphery of systems with a potential for landfall. (''NHOP 2015'', p. 5–12).}} During the "fix" mission, the ARWO directs the aircraft to the true center or ''vortex'' of the storm by monitoring the radar presentation, temperature, pressure, and mapping the wind fields as the aircraft makes left-hand turns. Vortices determined by individual parameters including visual observation may not coincide at the same geographic location. Surface and upper-level centers may be displaced by many miles. In order to make a reliable evaluation of its size and configuration, the crew flies through the disturbance using "Flight Pattern Alpha" consisting of [[cardinal directions|intercardinal]] headings with legs {{convert|105|nmi|km|sigfig=2}} in length.{{efn|"'''5.8.1. Flight Pattern ALPHA Operational Details. 5.8.1.1. Flight Levels and Sequence.''' Flight levels will normally be 1,500&nbsp;ft, 925 [[Pascal (unit)|hPa]], 850 hPa, or 700 hPa, depending on data requirements and flight safety. Legs will normally be 105 nm long and flown on intercardinal tracks (45 degrees off cardinal tracks). The pattern can be started at any intercardinal point and then repeated throughout the mission. Prior to starting an inbound or outbound track the aircrew should evaluate all available data, e.g., radar presentation, satellite photo, for flight safety. Once started on course, every effort should be made to maintain a straight track and the tasked altitude. A horizontal observation is required at each leg end point. This data is transmitted immediately. The ALPHA pattern may be modified to satisfy unique customer requirements (such as extending legs to examine the wind profile of a strong storm) or because of proximity of land or warning areas." (''NHOP 2015'', p. 5–19).}} The Alpha pattern is repeated at least twice during the mission, which will typically see a penetration of the eye of the system four times. Patterns may also be adjusted to meet circumstances encountered in the system. In August 2011, as [[Hurricane Irene]] neared the [[Delmarva Peninsula]] between landfalls, a 53rd WRS ARWO directed a pattern with shorter legs and more rapid turnarounds because of the proximity of land, making seven center fixes in one flight.<ref name="nlm"/> Flight weather data is continuously collected and sent directly to the NHC by satellite communications. Since the WC-130J is not equipped for aerial refueling, the alpha pattern continues until minimum fuel reserve is reached, or until the NHC has received all the data it requires.<ref name="53wrsmp"/>

Major hurricanes (Category 3 or higher in the [[Saffir–Simpson scale]]) are entered at approximately {{convert|10000|ft|abbr=on}} altitude.{{efn|Atmospheric pressure is determined by deviations from "standard levels" used by meteorologists worldwide. Stronger storms have lower pressures, and the lower the actual altitude from the standard level, the lower the pressure. The Hurricane Hunters use autopilot to fly a steady atmospheric pressure of 925 (2500&nbsp;ft/762&nbsp;m), 850 (4780&nbsp;ft/1457&nbsp;m), or 700 [[millibar]]s (9880&nbsp;ft/3011&nbsp;m) of pressure. Storms of category 3 strength or greater are flown at 700mb. By using a radar altimeter to measure actual altitude above the surface, the ARWO calculates the "height of standard surface" reported to NHC to make these determinations.}} While penetrating the [[Eye (cyclone)|eyewall]], a dropsonde is released to determine the [[maximum sustained wind]]s at the surface and a second dropsonde is released in the [[Eye (cyclone)|eye]] to detect the lowest pressure at the surface. After exiting the eye, the ARWO creates a Vortex Data Message that includes the precise latitude and longitude of the storm center as well as its maximum winds, maximum temperature, and minimum sea level pressure.{{efn|A description of the contents of the vortex data message is [http://jrscience.wcp.muohio.edu/downloads/VortexDataMessage.pdf here]. Standard sea level pressure is 1013 millibars. A "supplemental vortex data message" gives a cross-section of weather data at 15-nautical mile intervals, both inbound and outbound, along the 105-mile intercardinal legs to locate damaging winds in the storm's quadrants. Observation requirements are summarized in Table 5-1, page 5.5, ''National Hurricane Operations Plan 2015'', linked below. During active tropical cyclones, the most current vortex data message can be found at <u>http://www.nhc.noaa.gov/</u> by clicking on ''Aircraft Recon'' under "Tools & Data".}} The average duration of a "Hurricane Hunter" mission is ten hours, with five to six hours on station, depending on the distance of the storm from base, when tasked to perform three fixes at three-hour intervals.<ref name="nlm">{{cite journal|last=Mitchell |first=Capt. N. L. |year=2013 |title=Into the Storm: A Hurricane Hunter Member Describes Her Missions in the Air While Her Concerns are For Those on the Ground |url=http://www.mydigitalrendition.com/publication/?i=139668&p=35 |journal=The Officer |volume=LXXXIX |issue=January–February |archive-url=https://archive.today/20130216121616/http://www.mydigitalrendition.com/publication/?i=139668&p=35 |archive-date=16 February 2013 |access-date=8 January 2013 }}</ref>