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Recent Questions

Question: Hello, I am tasked to find annual/monthly global wind averages at ground speed and/or at different altitudes no greater than 15,000 feet AGL. Could you point me in the right direction to obtain this data? — Scott Carter

Answer: This isn not an especially simple or easy task. A couple of resources we thought might get you going include surface wind roses that can be generated for many locations worldwide using a tool created by the Iowa Environmental Mesonet site. You can start at a map of NC with clickable stations that will produce seasonal and monthly wind roses for the selected location, and also note that a drop-down box near the top of the page provides access to maps of other regions. The address for this tool is mesonet.agron.iastate.edu/sites/locate.php?network=NC_ASOS.

In addition, the International Research Institute for Climate & Society, though Columbia University, has a site with access to multiple climatological tools available at iridl.ldeo.columbia.edu/maproom/Global/Climatologies/index.html. There is a zoomable monthly wind climatology tool included in this page, which allows inspection of wind information at multiple levels, ranging from near the surface (1000 mb) to 10 mb. Based on your requirements, you'd be most interested in data from 925 mb (approximately 2500 ft AGL on average), 850 mb (about 5,000 ft), 700 mb (about 10,000 ft) and 500 mb (about 18,000 ft).
May. 20, 2015 | Tags: cool sites, normals, winds

Question: I thought an outflow from some thunderstorms just passed by the house. I looked on iControl, but did not see anything, but it clearly showed up on DualDoppler. Why didn't it show up on the iControl view? — Sandy McNeill

Answer: Outflow boundaries can be visible on radar due to convergence of air along the boundary concentrating dust, insects, birds and other reflectors, in addition to creating a turbulent mixture of contrasting airmasses with differing temperature, humidity and density properties. This is a low-altitude phenomenon that is usually also a rather weak echo. From our own DualDoppler 5000 (both the images/lapses and the live stream), we display a more or less raw reflectivity image with relatively little additional processing or manipulation. On the other hand, iControl is a viewer that consolidates information from the entire network of National Weather Service Doppler radars into a national mosaic. In the process of putting together, it is likely that some processing is being applied that is meant to remove, to the extent possible, spurious echoes, ground returns, and non-precipitation echoes. It is quite possible the automated algorithms that carry out this processing filter out small, weak features having little vertical consistency, and in so doing remove most if not all very shallow, narrow outflow boundary echoes.
May. 19, 2015 | Tags: instruments, weather radar, wral.com

Question: Can you please tell me how much total rainfall was received in Mount Olive from May 8 thru May 11? We were hammered. — Ron Page

Answer: We can only make a rough estimate due to variability of rainfall amounts and the distance to nearby surface measuring stations, but based on a number of those, combined with radar rainfall estimates over the same area, it appears that in the time span you asked about, rainfall would have totaled up to something in the range of 2.75 to 3.25 inches, which is around 2 inches above normal.
May. 18, 2015 | Tags: past weather, rain

Question: When R we going to have meteor showers? — Sheila Kendrick

Answer: While rather minor meteor showers are underway and recur on a frequent basis, the next two major showers are the Perseids, starting July 17th, peaking around August 12th and ending August 24th, and then the Geminids, starting December 7th, peaking around December 13th and ending December 17th. For more detailed schedules that include lesser showers, see the calendar sections of the web sites of the American Meteor Society (www.amsmeteors.org/meteor-showers/meteor-shower-calendar) or the International Meteor Organization (www.imo.net/calendar).
May. 17, 2015 | Tags: astronomy, cool sites

Question: The weather page used to include pollen levels, moon phase, sun and moon rise and set times, and air quality ozone/pollution levels. Where is all this info now? — Katie

Answer: All of those pieces of information remain available on our site, with the moon and sun data located under the "Almanac" section, and the links to information of pollen, ozone and other air quality issues found via the "resources" or "weather resources" links. Note that the weather resources section is two pages long, so be sure to check both for any information you're looking for that doesn't show up elsewhere.
May. 16, 2015 | Tags: air quality, astronomy, pollen, wral.com

Question: Driving to work the morning of May 4th, Sanford, looking into the Eastern sky, I saw an orange color streak about 15-20 degrees from the horizon. Time was around 3:45. It looked like the streak from some fireworks and not a shooting star. Any ideas? — Steven H Garner, Sr

Answer: The main things we could check for on that morning were the possibility of fireball meteors or space launches that might have been visible in that direction, or perhaps the re-entry of some orbital object. We were unable to find any reports along those lines that corresponded to the timing of your obsevation (although, given the date, we can't help wonder if it was a quick glimpse of the Millenium Falcon!)

Based on your location and the direction you cited, we also thought that something like air-dropped or ground-launched flares or perhaps artillery associated with training in the Fort Bragg area might be another possibility. If anyone else reading this knows of something else going on near Sanford that morning, feel free to let us know and we'll follow up here.
May. 15, 2015 | Tags: astronomy, atmospheric optics

Question: Will WRAL re-air your climate change weather special that aired Wednesday May 6th? Many of us were in church Wednesday night and would really like to see your work. Thank you. — Anonymous

Answer: We aren't certain if the documentary, "Exploring Climate Change," will air again on television, but it is available any time for viewing on demand at our web site. Just go to wral.com/14536286/ and click the blue "play" button on the title image near the center of the page.
May. 14, 2015 | Tags: climate change, wral.com

Question: What characteristics of precipitation define whether it is snow or freezing rain/sleet? — Holly Donnelly

Answer: Almost all wintry precipitation begins as snow, but it may have to fall thousands of feet to reach the surface, and the temperature structure of the air it falls though, along with the temperature of the air near the ground and the ground surface, determines whether it will reach the ground as rain, snow, sleet or freezing rain. If the snow falls into and through air that is significantly above freezing in a layer deep enough to melt it, and the ground is above freezing as well, the precipitation occurs as rain. If the snow crystals fall all the way to the surface through air that is below freezing, or nearly so, they can arrive at the surface as snow. If the snow encounters a layer that is warm enough and deep enough to melt it, but then falls though a deep layer of sub-freezing air below prior to reaching the ground, it may re-freeze into small solid particles of clear ice. These are called ice pellets, or more commonly sleet. If the snow falls through a layer sufficiently warm and deep to melt it, and then falls into a layer of air that is below freezing or near freezing but that is not deep enough of cold enough to refreeze the droplets, and the ground or objects near the ground are below freezing, then the droplets may spread out on those surfaces and then freeze into a clear glaze of ice - this is the process for freezing rain.
May. 13, 2015 | Tags: general meteorology, winter weather

Question: Why does so many thunderstorms this year have hail with them? I can remember time when you never saw much hail around here. — John Gibbs

Answer: From late March through about the start of May we had several episodes of upper level troughs forming over the eastern half of the United States and pulling relatively cool air aloft into the region, with a couple of other periods in which temperatures were generally a little warmer, but in which moist low level air was overlain by some layers of drier air at mid-levels. In each case, when passing disturbances helped trigger thunderstorms, the effective freezing level was rather low, either due to the cold air aloft or to evaporative cooling effects in the case of the dry mid-level layers. The lower the freezing level in the presence of thunderstorms, the better the chance of hail reaching the ground before melting. In most cases, the storms during these episodes were not extremely intense, so that most of the hail was too small to constitute severe weather (defined as hail with a diameter of one inch or greater).
May. 12, 2015 | Tags: hail, severe weather, thunderstorms

Question: You are doing a report on climate change. I have been wondering if the water temperature change that is affecting so much of our weather is also being affected by the 7 active volcanoes in our world right now. Many pouring into our oceans. Can't this many affect our overall temperature of water over time? — Vivian Gregory

Answer: Volcanoes form a small part of the overall energy source that includes steam vents, mid-ocean ridges, geysers, upwelling heat that travels through the earth's crust and so on, all of which is often combined under the umbrella term "geothermal heating." It turns out that while there are localized variations associated with eruptions, new formations and the closing off of older sources, the overall contribution from geothermal sources on a global scale doesn't appear to change much over long time scales. It also turns out that this heating source averages out to about .09 watts per square meter (W/m2). This compares to about 239 W/m2 of solar energy reaching the surface, and estimates that the difference between pre-industrial and recent carbon dioxide concentrations contributes about 1.6 W/m2, about 18 times greater than the geothermal heating component.

One other bit of scale difference that helps to visualize this, is to note that the sheer volume of the oceans so greatly exceeds that of any lava that enters them. The lava certainly transfers heat in a very dramatic way to water in the immediate vicinity of the flow, but consider that, as examples, the eruption volume from Mt Pinatubo was about 1.2 cubic miles of material, and as another example a 1984 eruption of Mauna Loa released about 4.8 cubic miles of material. By comparison, the volume of ocean water world wide is estimated at about 321,000,000 cubic miles (around 353 quintillion gallons).
May. 11, 2015 | Tags: climate change, heat, volcanoes

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