Climate Summary

Temperature and Precipitation by climate division
Departures from Normal for August 2010 - based on preliminary data.

August 2010 in North Carolina was hot statewide and generally dry, although many locations were able to experience periods of extended and heavy rainfall. Across the state, average daily mean temperatures ranked on the high side, with several locations ranked as the 5 warmest on record. In western NC, most towns in central and southern mountains generally had experienced their #1 or #2 warmest August on record. However, the high ranks in the daily mean temperatures were due more to record warm lows than extreme daytime high temperatures. Statewide, August 2010 in NC ranked at the 46th driest and the 3rd warmest since 1895.

Precipitation for August 2010
Based on estimates from NWS Radar
Data courtesy NWS/NCEP

Precipitation for August 2010: Percent of Normal
Based on estimates from NWS Radar
Data courtesy NWS/NCEP

Impacts to Agriculture and Water Resources

Heat and dry conditions continued to cause problems for crops. Rainfall in western NC brought relief to some, but it’s too late for many corn growers, especially in eastern parts of the state.

Monitoring data from reservoirs, streams, and groundwater supplies suggest minimal impacts through August.

The NC Drought Management Advisory Council continues to have weekly technical conferences to review conditions and make recommendations to the US Drought Monitor. While improvements have been observed in western NC, moderate and severe drought is still observed at the end of August in the northern coastal plain.

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

Summer Statistic -- Hottest Summer on Record

August ends the meteorological summer for 2010, and preliminary numbers confirm what we’ve all been feeling outside: 2010 was the warmest summer on record. One of the more interesting aspects of this record warmth is the contribution from overnight minimum temperatures, which were ranked #1 warmest for almost every station in NC. A few locations with long records in the southern mountains set records for average maximum temperatures, but for most other locations, the summer of 2010 ranked as a top 10 warmest for maximum temperatures.

What caused this pattern? It’s likely due to a combination of several factors, but one interesting feature that made 2010 unique was the high humidity through most of the summer. Unlike other very warm summers, 2010 brought consistent winds from the Gulf of Mexico and the associated moisture. However, not all of that moisture came down as rainfall. Some areas (most notable the upper Yadkin River basin) finished the summer with above normal rainfall. But most of the rest of NC was relatively dry for the summer. There is possibly also a contribution from local land use – as we urbanize, many cities and towns have more land surfaces that store heat (concrete, asphalt streets and shingles) that would also likely contribute to warmer minimum temperatures. And while that is certainly observed in the longer-term trends in city minimum temperature records, we observed very high minimum temperatures during the summer of 2010 in both urban and rural locations.

What about El Nino? El Nino is gone, and La Nina (the cool phase of the ENSO pattern) has quickly emerged. While La Nina is associated with increased tropical storm activity and dry, warmer winters in NC, neither El Nino nor La Nina have shown to be closely linked with summer temperatures in NC.

And what about global warming? It’s difficult to attribute the climate of any single month or season to changing climate patterns. Just like we can’t say that the very cold winter we had in 2010 was due to global warming, we also can’t attribute the record warmth in the summer to longer-term warming.

Speaking of La Nina... La Nina has quickly emerged in the tropical Pacific Ocean. This phase of the El Nino / Southern Oscillation (ENSO) is associated with cooler ocean temperatures in the eastern tropical Pacific Ocean. Historically, La Nina is associated with increases in the number of Atlantic Tropical storms. Indeed, as I write this, there are 3 named storms in the Atlantic and another tropical wave that could become Hermine. La Nina is also typically associated with warmer, drier winters in NC. While La Nina doesn’t guarantee drought conditions to extend through the winter and into next year, we will be closely monitoring rainfall patterns and water resource data to see if NC is primed for drought next summer.

New CRONOS Features

Since the summer began, several new parameters and features have been added to the NC CRONOS Database.

Climate Normals
CRONOS users will now find the option to retrieve climate normals on the daily retrieval pages of many stations (such as this page for the Lake Wheeler Road Field Lab). The normals data comes from nearby COOP stations with longer-term temperature and precipitation data. Both the normal range or value and the departure from normal can be retrieved for five parameters: max, min and mean temperature, degree days, and precipitation.

Monthly Evapotranspiration
On the monthly retrieval page for many stations, monthly total evapotranspiration can now be retrieved. This includes reference crop evapotranspiration, crop evapotranspiration for a given crop and growth stage, and open water evaporation.

Local Storm Reports
On both the hourly and daily data retrieval pages for all stations, Local Storm Reports can be retrieved. This feature ties in with the new Local Storm Reports Database, which includes reports issued by the National Weather Service about storm events from across the country. Event types covered include severe weather and thunderstorms, winter weather, flooding and heavy rain, storm damage and more.

CRONOS Advanced Map
Our famous CRONOS map has gotten a facelift! The new CRONOS Advanced Map features interactive options for viewing atmospheric conditions, as well as station information. Most weather station data is plotted inside color-coded circles. Hovering over the station data will show a breakdown of the latest observations; and retrieving historical data from the CRONOS database takes only a single click. Current weather overlays now include satellite and weather advisories, watches, and warnings from the National Weather Service. And automatic data updates allow you to view the latest information without having to refresh your page. Past weather conditions can be easily accessed, as well as viewing past Radar up to 1995. This new map utilizes does not require any packages to download, using your browser to display data in a whole new way.

Like the old map, weather data is available from North Carolina and surrounding states. New weather variables that are displayed include graphical depictions of sky conditions and wind speed/gust arrowheads. Looking for a certain location? You can search the CRONOS database for a station name or city, or you can now search the map to find an address, city, or landmark.

Check it all out at http://nc-climate.ncsu.edu/map

Showing past hourly radar and sky conditions at 11:00AM EST on January 20th, 2009.

Showing past hourly radar and wind gusts at 2:00AM EST on September 3rd, 2010 as Hurricane Earl sits offshore.