Climate Summary

Temperature and Precipitation by climate division
Departures from Normal for May 2011
Based on Preliminary Data

May 2011 was a bit warm and generally dry. While temperatures were not as much above normal as the previous month, temperatures for most locations were1-3 degrees Fahrenheit above normal in May. And for many locations, especially in the southern mountains and coastal counties, May was very dry – many locations in these areas reported less than 1 inch of precipiation for the entire month. In the southern mountains, both Murphy and Brevard recorded the 5th driest May on record. In far eastern NC, most reporting gauges reported at least in the driest 10 Mays on record. New Bern, Kinston, and Elizabeth City reported May 2011 as the #1 driest May on record. Elizabeth City also reported the 3rd warmest May on record. Statewide, temperatures ranked as the 37th driest and 34th warmest since 1895

However, May was much quieter for most of the state, without the widespread reports of damage from severe thunderstorms and tornadoes. While no tornadoes were reported, there were many reports of hail, especially in western North Carolina in May. There were 142 reports of hail in May 2011 as compared with only 84 in April 2011.

Local Storms Reports for May 2011
Preliminary Count of LSRs courtesy National Weather Service

Precipitation for May 2011
Based on estimates from NWS Radar
Data courtesy NWS/NCEP

Precipitation for May 2011: Percent of Normal
Based on estimates from NWS Radar
Data courtesy NWS/NCEP

Impacts to Agriculture and Water Resources

Dry conditions are primarily impacting eastern NC, which did not benefit from wet conditions in the previous month like western NC. While most surface reservoirs in central and western NC were able to benefit from periods of heavy rainfall in April and May, most water in eastern NC for drinking and irrigation comes from groundwater. There are growing concerns about crops in eastern NC that have missed out on timely rainfall. The recent extreme heat, combined with a lack of moisture in the top soil, may have substantial impacts especially on corn production as the period from late May through mid-June is when kernels often set. Insufficient moisture during this critical period can prevent a successful corn crop.

Streamflow and shallow groundwater levels in eastern NC have also been dropping, and some groundwater monitoring wells in coastal counties have been moving toward record low levels for this time of year.

US Drought Monitor for North Carolina
Courtesy NC DENR Division of Water Resources

Climate Outlook

Will the heat and dry conditions continue? We’ve moved into the time of year when we lose almost all ability to predict seasonal climate patterns. Unlike the winter season when we often have good guidance on temperature and precipitation shifts, in the summer all predictability is lost out beyond a few days. The exception to this is overall tropical storm activity.

Tropical Cyclone Outlook

Scientists have made great progress in recent years in predicting the total number of tropical cyclones that are likely to form each year. For 2011, most projections (including those by NOAA, Colorado State University, and NC State University) are calling for another active tropical season. The consensus outlook calls for 13-17 cyclones that will reach Tropical Storm strength on the Saffir-Simpson Scale and 7-10 storms that will reach Hurricane strength. The long-term average is 10 Tropical Storms and 6 Hurricanes.

Unfortunately, scientists aren’t yet been able to predict this far in advance how many storms are likely to affect any given area such as North Carolina. In recent years we’ve had very active seasons with zero storms impacting North Carolina. We’ve also recently had years where numerous storms formed and impacted the Carolinas. But with such warm ocean temperatures and a weakening La Nina (and no El Nino forecasted to form), conditions are generally favorable for tropical cyclones to form. The more that form, the better the chances that one or more will affect North Carolina.

New Training Video for Hurricane Database

In light of the start of Hurricane Season, the State Climate Office – with the help of former intern David Church – recently put together a video to train users to navigate through our hurricane database. This video guides users on the many ways to search for tropical cyclones, and introduces various tools such as the mapping and tabular display of storm tracks and associated measurements of maximum wind speed and minimum central pressure. To access the video, click on the image below or visit http://www.youtube.com/watch?v=8lqhbXnm7Js