21-HURRICANE DATA PROVISIONS (HDP)

1

HURRICANE DATA PROVISIONS (HDP)

2021 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). Counties triggered are 

determined by the Saffir-Simpson Hurricane wind scale using data provided from the National 

Hurricane Center operated by the National Oceanic and Atmospheric Administration (NOAA).

Trigger counties are defined as counties that intersect the hurricane corridor as defined under 

these provisions. 

1. Data

The data used for HIP-WI 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 their 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/data/international-best-track-archive-for-climate-stewardshipibtracs/v04r00/access/csv/

2. Loss Triggers

The most recent county boundary shapefile from the US Census Bureau is used to determine if 

the hurricane corridor intersects the county (or equivalent) boundary. 

(https://www.census.gov/cgi-bin/geo/shapefiles/index.php). Adjacent counties are determined 

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
21-HURRICANE DATA PROVISIONS (HDP)

2

using the county adjacency file from the US Census Bureau 

(https://www2.census.gov/geo/docs/reference/county_adjacency.txt).

NOAA publishes IBTrACS datasets approximately two weeks following the occurrence of a 

hurricane landfall. Once published, RMA will obtain the IBTrACS dataset and determine the 

trigger counties. If NOAA publishes an updated final IBTrACS dataset prior to the start of the 

following hurricane season, which begins June 1st of the following year, RMA will process the 

updated data to determine if a loss is triggered for any additional counties but will not remove 

any previously triggered counties.

3. Storm Center Points

The latitudes and longitudes are projected in a continental USA Albers Equal-Area projection to 

determine the storm center points when the hurricane strength is greater than or equal to a 

Category 1 hurricane (USA_SSHS >=1). In addition, RMA will calculate a storm 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 storm 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 storm center point 

for the determination of payment.

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 = MMMMMM(UUUUUU_RR64_NNNN,UUUUUU_RR64_ ,UUUUUU_RR64_ SS,UUUUUU_RR64_NN )

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 M radius circle around 

the storm center point.

5. Estimated Storm 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 center point and wind extents are 

measured. 

The estimated 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 
21-HURRICANE DATA PROVISIONS (HDP)

3

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

(USA_WINDts). 

A line is drawn between the two center points, and the bearing and distance (Distancefull) is 

used to calculate the estimated center point. The same bearing is used, but the distance is 

calculated using the following formula:

Distance = DDDDDDDD DDDDDDffffffff ∗ UUUUUU_WWWWWWWWhuuuuuu−64

UUUUUU_WWWWWWWWhuuuuuu− UUUUUU_WWWWWWWWtttt

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

following formula:

Buffer = MMMMMM(

HH HHHHHHHHHHHHHHHH HHHHllll

2 , HHHHHHHH HHHHHHHH HH llll ∗ (1 − UUUUUU_WWWWWWWWhuuuuuu−64

UUUUUU_WWWWWWWWhuuuuuu− UUUUUU_WWWWWWWWtttt

))

In cases where a hurricane forms close to land, the same process is employed 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 

70knots 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_

NE

USA_R64_

SE

USA_R64_

SW

USA_R64_

NW

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
21-HURRICANE DATA PROVISIONS (HDP)

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. Line segments are then drawn between each pair of 

hurricane buffers that are tangent to both hurricane buffers to develop the hurricane corridor. 

The hurricane corridor is comprised of the tangent lines and arcs of the hurricane buffers or in 

some cases only the tangent lines are used if they intersect prior to the buffer. Figure 2 below 

shows the final hurricane corridor.
21-HURRICANE DATA PROVISIONS (HDP)

5

Figure 2 – Hurricane Corridor

The hurricane corridor is then projected on the continental USA Albers Equal-Area projection. 

Any county that intersects the hurricane corridor is determined to be a trigger county. Any 

counties adjacent to a trigger county (according to the US Census County Adjacency File) are 

also determined to be trigger counties. The trigger counties and date (ISO_TIM) will be 

published in the actuarial documents. Payments will be issued in accordance with the HIP-WI

endorsement.