22-HDP

(Released June 2021)

HURRICANE DATA PROVISIONS (HDP)

2022 AND SUCCEEDING CROP YEARS 

These provisions document the procedures for determining the counties where a loss is 

triggered for Hurricane Insurance Protection – Wind Index (HIP-WI). The county losstrigger is

determined using data provided from the National Hurricane Center operated by the National 

Oceanic and Atmospheric Administration (NOAA) and the US Census Bureau, which may be 

modified in the Special Provisions of Insurance.

1. Data

The data used for determining the county loss trigger is the International Best Track Archive for 

Climate Stewardship (IBTrACS) dataset from the National Climatic Data Center within the

National Hurricane Center operated by NOAA and hosted on the website below (or a successor 

website). The table below shows the variables used to develop the wind extents and determine 

the trigger counties. 

IBTrACS generally records new values for these variables in three-hour intervals. If additional 

data points exist, RMA will use the three-hour interval data only. If data is missing, RMA will 

coordinate with NOAA to fill in the missing data. IBTrACS data can be found at the following 

link: 

https://www.ncei.noaa.gov/products/international-best-track-archive, or successor website.

2. County Data

The county boundary shapefile from the US Census Bureau at https://www.census.gov/cgibin/geo/shapefiles/index.php, or successor website, is used to determine if the hurricane 

Variable Column Name Units

Season SEASON Year

Name NAME N/A

Time ISO_TIME UTC (YYYY-MM-DD HH:MM:SS)

Latitude USA_LAT Degrees North

Longitude USA_LON Degrees East

Maximum Sustained Winds USA_WIND Knots

Hurricane Category USA_SSHS N/A

Wind Extents Northeast USA_R64_NE Nautical Miles

Wind Extents Southeast USA_R64_SE Nautical Miles

Wind Extents Southwest USA_R64_SW Nautical Miles

Wind Extents Northwest USA_R64_NW Nautical Miles
2

corridor intersects the county boundary. Adjacent counties are determined using the county 

adjacency file from the US Census Bureau at

https://www2.census.gov/geo/docs/reference/county_adjacency.txt, or successor website. 

The most recent shapefile and county adjacency file available at the contract change date will 

be used to determine trigger counties. Census county boundaries and adjacent counties may 

be modified by Special Provisions of Insurance.

3. Storm Center Points

IBTrACS uses World Geodetic System 1984 longitude and latitude coordinates which locate the 

center of the storm in 3-hour intervals. When wind speeds reach or exceed 64 knots 

(USA_WIND >= 64), the storm center point is a hurricane center point. In addition, RMA will 

calculate a hurricane center point between the last tropical storm center point and the first 

hurricane center point (i.e., when a tropical storm strengthens to a hurricane) and another 

hurricane center point between the last hurricane center point and the first tropical storm 

center point (i.e., when a hurricane weakens to a tropical storm). A tropical storm point, by 

itself, does not constitute a hurricane center point for determining a county loss trigger.

4. Wind Extents

The maximum of the USA_R64(NE, SE, SW, NW) values are used as the radius of a circle around 

each storm center point. These are referred to as the hurricane buffers.

Hurricane Buffer = Max(USA_R64_NE,USA_R64_SE,USA_R64_SW,USA_R64_NW)

Example:

Suppose the maximum distance of the hurricane wind extent from the storm center point is 

35 nautical miles (nm) for northeast quadrant, 25 nm for the southeast quadrant, 10 nm for 

the southwest quadrant, and 30 nm for the northwest quadrant. In this case, the maximum 

distance of the hurricane wind extent from the storm center is 35 nm (northwest quadrant). 

The hurricane buffer is then a 35 nm radius circle around the storm center point.

5. Estimated Hurricane Center Point and Buffer

A hurricane ceases to exist at some point between where the last hurricane point is measured 

and when the first tropical storm point is measured. The maximum sustained winds 

(USA_WIND) value is used to calculate where the estimated hurricane center point and wind 

extents are measured.

The estimated hurricane center point and buffer are calculated based on the last hurricane 

center point (USA_LAT and USA_LON) and maximum sustained wind speeds (USA_WINDhurr) 

and the first tropical storm center point (USA_LAT and USA_LON) and maximum sustain wind 

speeds (USA_WINDts). 
3

A bearing is calculated between the two center points, and the bearing and distance 

(Distancefull) is used to calculate the estimated center point. The distance is calculated using 

the following formula:

Distance = Distancefull ∗

USA_WINDhurr−64

USA_WINDhurr− USA_WINDts

The estimated buffer is calculated using the last hurricane buffer (HurricaneBufferlast) and the 

following formula:

Buffer = Max(

HurricaneBufferlast

2

, HurricaneBufferlast ∗ (1 −

USA_WINDhurr−64

USA_WINDhurr− USA_WINDts

))

The same process is used during the formation of a hurricane, using the last tropical storm 

point and the first hurricane point. 

Example:

Given the table below:

The last hurricane storm point occurs on September 30th at 0:00 and the first tropical storm 

point occurs on September 30th at 3:00 hours. The maximum sustained wind speeds are 70

knots and 60 knots, respectively. Figure 1 below shows the estimated center point and 

buffer.

SEASON NAME ISO_TIME USA_LAT USA_LON USA_SSHS USA_WIND

USA_R64_

N E

USA_R64_

SE

USA_R64_

SW

USA_R64_

N W

2020 HURRICANE 9/29/20 0:00 21.3000 -74.0000 0 60

2020 HURRICANE 9/29/20 3:00 21.6999 -74.5877 1 65 15

2020 HURRICANE 9/29/20 6:00 22.1000 -75.1000 1 70 25 15 20

2020 HURRICANE 9/29/20 9:00 22.5072 -75.5228 1 75 30 15 15 20

2020 HURRICANE 9/29/20 12:00 22.9000 -75.9000 1 80 35 25 10 30

2020 HURRICANE 9/29/20 15:00 23.2574 -76.3003 1 90 35 20 11 30

2020 HURRICANE 9/29/20 18:00 23.6000 -76.7000 1 80 30 20 11 25

2020 HURRICANE 9/29/20 21:00 23.9649 -77.1001 1 75 20 15 20

2020 HURRICANE 9/30/20 0:00 24.3000 -77.5000 1 70 10

2020 HURRICANE 9/30/20 3:00 24.5650 -77.9152 0 60
4

Figure 1 – Estimated Center Point and Buffer

6. Hurricane Corridor

When the storm center points and corresponding hurricane buffers are plotted, the result is a 

series of (often overlapping) circles. A convex hull is calculated for each pair of adjacent buffers

which results in a series of ovals. Figure 2 below shows the convex hulls for the adjacent 

buffers.
5

Figure 2 – Convex Hulls

7. Determining County Loss Triggers

Once the convex hulls are calculated, county loss triggers are determined. The convex hulls 

and the county shapefile are mapped in the same coordinate reference system. Any county 

shape that intersects the convex hulls meets the county loss trigger. Any county that is 

adjacent (according to the US Census Bureau county adjacency file) to a county that is 

intersected by the convex hulls will also meet the county loss trigger.

The county loss trigger and date will be published in the actuarial documents. Payments will be 

issued in accordance with the HIP-WI endorsement. NOAA publishes IBTrACS datasets 

approximately two weeks following the occurrence of a hurricane landfall. Once published, 

RMA will obtain the IBTrACS dataset and determine whether a county is triggered. If NOAA 

publishes an updated final IBTrACS dataset following the hurricane season, RMA will process 

the updated data to determine if any additional counties are triggered. Counties previously 

identified as being triggered, will remain triggered.

RMA will use the R programming language to implement these provisions. Sample computer 

code to determine triggered counties can be found at: 

https://rma.usda.gov/Topics/Hurricane-Insurance-Protection-Wind-Index.