NEW! Wind Rose Tool to Show Distribution of Wind Speed and Wind Direction

A new tool recently developed by Graduate Assistant Megan Embrey allows users to generate wind roses for all CRONOS weather stations across the Southeast with hourly observations of wind speed and wind direction. With this tool, users will be able to choose their desired station, date range, and unit of measurement, as well as how often the wind speed data will be incremented. In addition to the standard frequency rings depicting winds at various speeds and directions, the wind rose tool also displays the frequency of calm winds, as well as statistics such as the maximum wind speed, maximum wind direction, average wind speed and average wind direction.

Wind rose generated for Raleigh-Durham Airport (KRDU) for the 10-year period from January 1, 2001 through December 31, 2010

Wind roses are particularly useful in determining the prevailing wind direction over an extended period of time, given that the direction of the rose with the longest spoke shows the wind direction with the greatest frequency. By extension, such a tool can be used in determining how various air pollutants will be dispersed, as well as in the beginning stages of airport runway construction, given that aircraft tend to perform their best take-offs and landings when they are pointing into the wind.

To view the new wind rose tool, please click here.

NEW! Training Video for the Winter Storm Database

Although winter storms are relatively rare in North Carolina, even a light snow or ice accumulation can have a significant impact across the state. Despite this importance, a detailed and searchable archive of winter storms affecting North Carolina was not available. This gap in our knowledge of North Carolina's winter climatology presented a research and educational opportunity for the State Climate Office.

Using the National Climatic Data Center's annual "Storm Data" publications, the State Climate Office developed a searchable Winter Storm Database in 2009. The database includes winter events since 1959, and each includes data such as statewide impacts, a meteorological summary, and affected locations. This product has been integrated with our existing database of weather data, which allows users to view hourly and daily observations from the event, as reported at weather stations across the state. Also, for many events, links are provided to case studies and accumulation maps created by the National Weather Service's Raleigh office. These provide additional insight into the meteorological setup and extent of impacts for a given event.

To aid clients in utilizing the database, the SCO has recently released a training video put together by Graduate Assistant Corey Davis. This video can be accessed through the main database page, or by clicking below.

NEW! White Christmas Tool

The SCO is often asked one main question as the holiday season approaches -- what are the odds of North Carolina having a white Christmas? In keeping up with this need, the SCO has recently developed a "White Christmas" tool. This product allows users to view the years in which a given station observed a white Christmas (defined as a trace or more of snowfall on December 24-26), as well as the total amount of snow that was observed over the 3-day period. The frequency of snowfall over the 3-day period is also generated, and is defined as the number of years with snowfall divided by the total number of years where snow was possible (based on the station's data record).

The White Christmas tool also allows users to view historical winter storm events that occurred over the Christmas holiday and affected the county in which the selected station is located. Each event is directly tied into our Winter Storm Database (see above), which gives information on impacts (number of injuries, amount of property damage), a meteorological summary of the event itself, and more. A screenshot of output from the White Christmas tool can be found below for NWS Cooperative station, Raleigh State University (317079).

Temperature and Precipitation Statistics for Christmas Day

Our Holiday Climatology product allows you to view various statistics from stations across the Southeast for a select list of holidays. Below you will find a table with the warmest, coldest and wettest Christmas Days on record for a few cities across North Carolina.

Climate Summary: Warm, Wet, and a Bit Stormy

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

November 2011 in North Carolina was warm and wet, especially in western North Carolina. Two major storms produced over 10 inches in parts of western NC. The last storm of the month produced flooding in the southern mountains. On November 16, a severe line of storms ripped across state, producing hail, damaging winds, and an EF2 tornado in Davidson and Randolph Counties. Statewide average precipitation for November 2011 ranked as the 18th wettest November since 1895.

The first half of November was a bit chilly, with many locations experiencing temperatures that ranked in the top 20 coldest on average. In contrast, the last 2 weeks of November were very warm, with temperatures that ranked in the top 10 warmest on record. Over all, temperatures in November 2011 averages to be warmer than normal with statewide average temperature ranking as the 36th warmest since 1895.

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

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

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

Impacts to Agriculture and Water Resources

As most warm season commodities have been harvested, the primary agricultural impacts in November were in winter grains. Adequate moisture in the topsoil has generally led to successful planting. Impacts to water resources were substantial in western NC, where heavy rain in the last few days of November was sufficient to eliminate drought impacts in the southwestern Piedmont. However, much of NC east of I-95 did not experience the beneficial rains, and areas of the southern coastal plain remain in moderate drought.

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

Seasonal Climate Summary: September – November (Autumn) 2011

We’re trying something new this month – a brief seasonal summary to put the past season into perspective. Let us know if you like this – it takes a bit more time but we think it might be of interest to some folks.

Let’s start with temperatures – after a very hot summer, temperatures were generally on the warm side during the autumn, at least in central and eastern NC. However, temperatures in western NC were cooler than normal. This is depicted nicely in the map below, which shows the percentiles in temperature distribution for sites across the region. Lower percentiles with cooler colors represent locations that were cool, while higher values and warmer colors represent locations that were warm for this time of year. Values in white represent more normal ranges for temperatures, generally between the 25th and 75th percentile (more typical temperatures for autumn).

In terms of rainfall, central and western NC did fairly well, as reflected both in the rainfall maps and in the improvements in drought conditions as compared to summer. And while eastern NC experienced somewhat drier conditions in September-November, remember that they were drenched with 7-14 inches from Hurricane Irene in August, which eliminated drought in that area overnight.

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

But the most interesting part of the past season is that it was relatively calm in terms of severe weather, especially in contrast to the previous seasons. During the summer, spring, and winter of 2011, NC experienced a hurricane, extreme heat & drought, a major tornado outbreak, and major winter storms. So in comparison, Autumn 2011 seemed quite mild.