National Park Service U.S. Department of the Interior Cape Hatteras Inventory & Monitoring Program Southeast Coast Network National Seashore Resource Brief: Summary of Weather and Climate Monitoring, 2010

Vital Sign Weather and climate are key drivers for ecosystem patterns and processes, affecting both Overview biotic and abiotic components alike. Continuous weather monitoring is an important factor in separating the effects of climate from the effects of human-induced disturbance on other vital signs (e.g., plant and animal communities and population dynamics). In support of these efforts, the SECN has compiled and analyzed data from existing sources to (1) determine status, trends, and variability of precipitation and temperature over time inside and around SECN park units; (2) determine the status, trends, and variability of derived weather data (i.e., drought indices) inside and around SECN park units; (3) track the location, magnitude, and frequency of extreme weather events that affect SECN park resources.

Significant Average monthly temperatures across all relevant RHmin occurring in December and the highest Findings stations ranged from a low of 37.5°F at Duck tide occurring in the summer months. station to a high of 80.3°F at Ocracoke weather station. Derivative climate measures indicated that growing season length varied from 273 to 293 days (Table 1) Average monthly temperatures were slightly above between weather stations and variation was also normal at most locations during the summer months present in other measures including the date of last and below normal during the winter. freeze. Table 1. Derived climate measures across all relevant Average monthly precipitation was higher than weather stations for annual temperature-based events at average during the late winter, early spring and late CAHA. summer months, but below normal the rest of year. Measure Min Max Average annual precipitation was above normal at Growing Season Length (days) 273 293 Cape Hatteras Airport, but below normal at Ocracoke. Maximum Temp. ºF (Tmax) 92 94

Number of Days Tmax ≥ 90ºF 1 12 Average monthly maximum relative humidity (RHmax) ranged from 79–99%, with the lowest maximum RH Number of Days Tmin ≤ 32ºF 33 52

occurring in December. Average monthly minimum Last Spring Date Tmin ≤ 32ºF 17-Feb 9-Mar

RH (RHmin) ranged from 52–73% with the lowest Earliest Fall Date Tmin ≤ 322ºF 7-Dec 7-Dec

Status of Comparisons of 2010 temperature data to the 30-year temperature average at Cape Hatteras Airport show that January, February, and December were colder than average (Figuree 1). In addition, the average annual Conditions – temperature was also colder than the long-term average at both stations. In contrast, temperatures during June, Temperature August, and September tended to have higher average maximum monthly temperatures (Tmax) than normal. This pattern was fairly consistent across all weather stations relevant to SECN parks.

100 100

Tmax Tmin 80 80

60 60

40 40

Temperature, in degrees F in degrees Temperature, 20 20 F in degrees Temperature,

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1. 2010 temperature departures from 30-year (1981 – 2010) average for Cape Hatteras Airport weather station. Depicted in these graphs are average maximum monthly temperature (Tmmax) and average minimum monthly temperature (Tmin). Gray shaded region represents 30-year average and standard deviation. Error bars represent standard deviation off average Tmax and Tmin in 2010.

* EXPERIENC E YOUR AM ERICA *

Status of Comparisons of 2010 precipitation data to the 30-year average at Cape Hatteras Airport show that January, Conditions – February, March, July, August and September experienced higher than average precipitation, while at Ocracoke Precipitation station only January, February, March and September experienced higher than average precipitation (Figure 2). Precipitation during the rest of 2010 was lower than average. Total annual precipitation at Cape Hatteras Airport station was 61.39 inches during 2010, which is 3.35 inches above normal. Total annual precipitation at Ocracoke station was 51.64 inches during 2010, which is 6.55 inches below normal. Cape Hatteras Airport is only one of two stations relevant to SECN Parks with above average total annual precipitation during 2010.

12 12 12 12 10 10 10 10 8 8 8 8 6 6 6 6 4 4 4 4 (inches) (inches) 2 2 2 2 Total Precipitation Total Precipitation 0 0 0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 2. Total monthly precipitation during 2010 and the 30-year (1981 - 2010) monthly averages for Cape Hatteras Airport (left) and Ocracoke (right) stations. The gray columns represent 2010 total monthly precipitation. The red circles represent the 30-year average; the lines indicate the 25th and 75th percentile of the 30-year normal data for each month.

About the The Southeast Coast Network (SECN) includes two national memorials, seven national monuments, Southeast Coast twenty parks, seventeen of which contain significant two national military parks, as well as a national Network and diverse natural resources. In total, SECN parks recreation area, national battlefield and an ecological encompass more than 184,000 acres of federally- and historic preserve. The parks range in size from managed land across North Carolina, South Carolina, slightly more than 20 to nearly 60,000 acres, and Georgia, Alabama, and Florida. The parks span a when considered with non-federal lands jointly wide diversity of cultural missions also, including managed with NPS, the Network encompasses more four national seashores, two national historic sites, than 253,000 acres.

About the In 1999, the National Park Service initiated a long- five goals for all parks with significant natural Inventory & term ecological monitoring program, known as “Vital resources: Monitoring Signs Monitoring”, to provide the minimum infrastructure to allow more than 270 national park  Determine the status and trends in selected Program system units to identify and implement long-term indicators of the condition of park ecosystem, monitoring of their highest-priority measurements of  Provide early warning of abnormal conditions, resource condition. The overarching purpose of natural resource monitoring in parks is to develop  Provide data to better understand the dynamic scientifically sound information on the current status nature and condition of park ecosystems, and long-term trends in the composition, structure,  Provide data to meet certain legal and and function of park ecosystems, and to determine Congressional mandates, and how well current management practices are sustaining those ecosystems.  Provide a means of measuring progress towards performance goals. The NPS Vital Signs Monitoring Program addresses

For More SECN Home Page: http://science.nature.nps.gov/im/units/secn/index.cfm Information SECN Reports & Publications: http://science.nature.nps.gov/im/units/SECN/reports.cfm Inventory & Monitoring Program: http://science.nature.nps.gov/im/index.cfm Data Downloads via the Natural Resource Information Portal: http://nrinfo.nps.gov/Home.mvc Follow us on Twitter at: http://twitter.com/SECoastNetwkNPS or @SECoastNetwkNPS Project Lead: Christina Wright at [email protected]

* EXPERIENCE YOUR AMERICA *