Climate Summary

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

Summer continues to be exceptionally hot, with near record temperatures across much of North Carolina in July. While NC didn’t experience the 110+F temperatures that were observed in the high plains region of the US, we did have the warmest July on record at Raleigh-Durham Airport, Cape Hatteras, Elizabeth City, and Aurora. As shown below, most other locations in NC experienced July temperatures that ranked in the top 5 warmest on record.

Several individual daily records for maximum temperature were broken in July 2011, and many locations reported temperatures in excess of 100F for several consecutive days. Unfortunately, guidance from the NWS Climate Prediction Center suggests that above normal temperatures are likely to continue in August.

Rankings for Average Mean Temperature for July 2011 for each long-term station
Climate Perspectives courtesy of the SE Regional Climate Center
http://sercc.com/perspectives

While temperatures were exceptionally warm in July, rainfall was a bit more plentiful as compared with previous months. As is typical during summer, thunderstorms produced locally intense precipitation amounts that in some locations was associated with local flooding. However, despite more generous rainfall amounts, much of eastern NC continues to experience very dry conditions. As shown below, May-July rainfall totals are the driest on record for locations including Wilmington, New Bern, and Morehead City.

Rankings for Total Precipitation for May-July 2011 for each long-term station
Climate Perspectives courtesy of the SE Regional Climate Center
http://sercc.com/perspectives

Local Storms Reports for July 2011
Preliminary Count of LSRs courtesy National Weather Service
http://www.nc-climate.ncsu.edu/lsrdb/index.php

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

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

Impacts to Agriculture and Water Resources

High heat places enormous stress on plants and water supplies - evapotranspiration rates increase with temperature, pulling additional moisture from the top soil and stressing plants when moisture is insufficient. Drought impacts in agriculture are most pronounced in corn, where much of the corn crop in eastern NC has been reduced or lost entirely. Heat also puts stress on pastures and the animals that feed in pastures, including horses and cattle.

Despite the heat, additional precipitation in July provided a bit of relief, especially in the northern Piedmont and Yadkin River basin. In addition, many surface reservoirs were able to capture the runoff produced by strong thunderstorms. As the heat is likely to continue in August, frequent rainfall will be needed to prevent further drought deterioration.

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

It's Not the Heat - It's the Humidity, Right?

The effects of excessive heat on the human body can be devastating. Heat index was devised as a way to determine how warm the outside temperature feels when humidity is factored in.

The recent extreme temperatures in NC were generally associated with a high pressure system that brought winds from the west and northwest. These conditions are typically associated with lower humidities. When winds blow from the south and southwest (as is typical for NC in the summer), very humid air is sent from the Caribbean and Gulf of Mexico. Dew point temperatures under typical conditions are often near or above 70F. This can make a day with 95F temperatures produce a heat index in excess of 110F.

But the high heat this summer has been associated with dew point temperatures closer to 60F. So what does this mean for heat index? Days with near record heat in July, including days when temperatures exceeded 100F, only once had heat indexes that exceeded 110F. In the summer of 2010 (another hot summer), Raleigh experienced 13 hours with Heat Index >= 110F. So far in the summer of 2011, Raleigh has experienced only 1 hour with Heat Index in excess of 110F. The graph below highlights the history of heat index at Raleigh-Durham Airport. Graphs and data for other locations across the region are available on the SCO’s Heat Index web page.

While some might argue that the drier air makes 100F more bearable, it's still extremely hot and can be dangerous.

AMS Applied Climatology Conference / AASC Annual Meeting

From July 18-20, climate office staff and students ventured to Asheville for the 19th Conference on Applied Climatology, sponsored by the American Meteorological Society (AMS). With 7 oral presentations to give and 8 posters to display, SCO staff and students kept extremely busy throughout the conference's entirety. The conference featured climate research and applications involving various sectors such as drought monitoring, water resources, agriculture, recreation, and education, with an underlying focus on ways to provide more effective climate services and improve climate communications with the broader community.

In addition, the July 20 luncheon, with Colorado State Climatologist Nolan Doesken as keynote speaker, featured an awards ceremony in which several SCO students were presented with the following awards:

• Corey Davis received the 1st place Outstanding Student Paper Award for the "Creation of a recreation climatology for the Southeast US"
• Heather Dinon received the 2nd place Outstanding Student Paper Award for her paper on "Relationships between ENSO and crop yield across the southeast US"
• Adrienne Wootten tied for the 3rd place Outstanding Student Paper Award for her paper on "Downscaling precipitation across the southeast United States"
• Heather Dinon also tied for the 1st place Outstanding Student Poster Award for her "Evaluation of techniques to estimate solar radiation and photosynthetically active radiation in the southeast US"

Poster session during AMS Applied Climatology Conference

The group concluded the week attending the 36th annual meeting of the American Association of State Climatologists (AASC) on July 21-22. Highlights from the meeting included: discussions of climate educational efforts in how to effectively communicate climate to the general public, and in curriculum recommendations for applied climatologists; SCEP project reports from 4 states; as well as a dinner with Keir Klepzig from USDA speaking on the birth of forestry in the Asheville area. After the meeting's conclusion, a small group of SCO staff and students along with a few other AASC attendees made a short trip to Mount Mitchell for a brief escape from the week's heat before traveling home.

SCO staff and students, along with other AASC attendees, atop Mount Mitchell