Ask Greg

Recent Questions

Question: It's World Meteorological Day, and it's being officially recognized with a new cloud named Asperitas. Is this a new type of cloud because of climate change? — Dunrovin

Answer: Asperitas is one of a number of new designations for describing certain cloud types and sub-types. This all comes as the World Meteorological Organization issued the first update to its International Cloud Atlas since 1987 on World Meteorological Day. The 2017 update adds a number of new designations, although the clouds themselves are not new, or a result of climate change. The "asperitas" label is now applied as a subtype (known as a "supplementary feature" in the cloud atlas), for example, stratocumulus asperitas or altocumulus asperitas. This type of cloud formation, which can have a very dramatic appearance under the right circumstances, was proposed as a new type called "undulatus asperatus" a number of years ago, with that description giving way to the new feature designation in the updated atlas. The only new cloud species in the updated atlas is "volutus," which is now an official name for the phenomenon that's been commonly referred to as a "roll cloud." There are a number of other new designations, and they are highlighted at www.wmo.int/wmocloudatlas/ICA-New-classifications.html, where you can also make your way back to the main site for the new cloud atlas. We've published a couple of blog posts about these types of clouds here on our site in the past. You can see those posts at www.wral.com/weather/blogpost/5356199/, which discusses the initial effort to apply a new name to the clouds, and www.wral.com/weather/blogpost/4367962/, in which we discuss the physical reasoning behind their appearance in response to photos sent in by a local viewer.
Mar. 29, 2017 | Tags: clouds, cool sites

Question: On Saturday we had a thunderstorm, and I asked you about the chances of frozen precipitation within seven days. So, today is Tuesday, and we had hail. It was not what I expected, but it was definitely frozen, and it's appearance fell within the prediction of "Thunder in the the Winter". Old wives' tale wins again. — John

Answer: Good observation, though it may be pushing the connection just a little! We've always heard the old rules of thumb as specifying "snow" within 7-10 days of a wintertime thunderstorm, which seems more meaningful in the sense that thunderstorms are just as capable of producing hail in August as in February or March, while we are extremely unlikely to ever have a thunderstorm followed by snow a week or so later during the summer.
Mar. 28, 2017 | Tags: folklore, snow, thunderstorms

Question: I have noticed that Sanford is usually cooler than surrounding areas in the morning. Any ideas why? Seems pretty consistent. — Alex Webb

Answer: The temperature for Sanford that is included on our weather maps on TV and the temperature maps and current condition page here on our web site comes from the weather station located at the Sanford-Lee County Regional airport and is maintained by the NC DOT Aviation Division following FAA guidelines. The airport there is in an area that features fairly sandy soil favorable for strong cooling at night and heating by day, and is topographically located with somewhat higher terrain just to the northeast, northwest and southeast, which can result in pooling of denser, cooled air, especially on nights with light winds and relatively clear skies. On early mornings with light winds and low humidity, temperatures may fall more precipitously there than some other airport locations, although there are times the Erwin and Southern Pines airports are similarly cool. Daytime temperatures often more closely match nearby locations, and overnight values come closer to doing so as well when cloudy and breezy conditions prevail.
Mar. 27, 2017 | Tags: cold, general meteorology, instruments, maps & codes

Question: I live in Clayton, and I would like to build a run in shed for the horses. Which way should I face the opening so that the prevailing winds don't blow in? — Liz

Answer: There can be some very localized terrain influences on wind directions such that your prevailing winds could differ a bit from those on the broader scale across the region, but most weather reporting sites around the area, which use "surface" wind measurements that are taken about 10 meters above ground level, consistently show our prevailing direction to be southwesterly for most of the year, with the exceptions being September and October, when the prevailing direction reverses to northeasterly. There are also some fairly common occurrences of gusty, cold winds from the northwest during the winter in the wake of passing cold fronts or departing coastal low pressure systems. If all that holds reasonably well for your property, you might be well-served to face the opening toward the southeast.
Mar. 26, 2017 | Tags: normals, weather & health, winds

Question: Greg, you are slipping. LOL, the chart you showed at 6 comparing cold to 1960 was "March Madness!" Keep up the good work. — Gene W Berg

Answer: A missed opportunity, indeed, but as you mentioned, the real madness was how cold March of 1960 was (or maybe, having all but one ACC team out of the tournament after the first weekend this year)! We've taken a chillier turn this March in the wake of a record warm February, but we're not even remotely as cold as that year. For reference, the "normal" average temperature for March at RDU is 51.1 degrees. Through the first three weeks of this March, we've averaged about 46.8 degrees, and will probably finish the month with an average a little warmer than that. March 1960, though, ended with an average temperature of 37.6 degrees. This was a full 4.4 degrees colder than the second coldest March since 1887, which was 1947 with 42.0 degrees. The third coldest March was in 1915, with 42.7 degrees. Not coincidentally, perhaps, 1915 was also notable for the 10-inch snow that occurred in Raleigh on April 3rd. Also of interest is that the very cold March of 1960 featured observed snowfall in Raleigh on the first three Wednesdays of the month!
Mar. 25, 2017 | Tags: cold, past weather, records/extremes

Question: I was going to ask since it is tornado season or severe weather season, when is are next chance of thunderstorms with severe weather? — Daniel

Answer: We have to note that since we sometimes answer these questions anywhere from a day or two to as many as several days in advance, discussions of particular upcoming weather features or storm events are highly subject to change and you should check out the most recent posted forecast information here on the web site, or tune in to our on-air weathercasts on WRAL or Fox 50 to confirm the latest outlook. That said, at the time we drafted this response there was no significant severe weather threat foreseeable within the upcoming 7 days. As you noted, though, we are in the time of year with the best chances of severe weather, and new systems with severe potential can crop up with only a few days' notice.
Mar. 24, 2017 | Tags: severe weather, wral.com

Question: Why is it that sometimes the high for a day on the WRAL weather site will be listed as a very different high compared to finding the high through the hourly readings? One example, the high on 3-21-2017 is listed as 80, but scrolling through the hourly temps the highs never exceeds 75. Thanks for the most interesting and accurate weather forecasts. Our family likes watching WRAL weather. — Aylin Regulski

Answer: We appreciate the kind words, and having your family as viewers! There are a couple of things that can contribute to the issue you asked about. First, the highest temperature of the day can occur between hours, so that on occasion any two hourly times may bracket the time of the maximum value. This would usually only result in a difference of a degree or two, though. A more pertinent factor is the manner in which our web site is set to retrieve hourly forecast information. While the main 7-day forecast numbers (highs/lows), weather icons, wind speeds and directions, and text descriptions for the Raleigh area are directly entered by WRAL WeatherCenter meteorologists, the hourly values, in addition to 7-day forecasts that you might use the "change location" feature for, are retrieved from a gridded information resource called the National Digital Forecast Database (NDFD), which is populated through a combination of computer modeling and adjustments by National Weather Service meteorologists. At the time you checked the hourly forecast, that database was indicating a max temperature in Raleigh for that Tuesday around 77 degrees while we were projecting around 80 (of course, while we have to choose a single number for the 7-day forecast, we would not have been surprised at the observed high ending up anywhere in about the 77-83 degree range, as alluded to by the written description portion of our forecast, which called for highs in the "upper 70s to low 80s" - the actual high observed at RDU that day turned out to be 82). Use of the NDFD allows us to include the ability for you to use the "change location" function on our main weather page to check forecasts for distant locations in our state, or anywhere across the United States.
Mar. 23, 2017 | Tags: maps & codes, wral.com

Question: During the storm this evening, the sky had an orange appearance, and then yellow. What causes that? — Pat Kowite

Answer: You were likely noticing the effect of the cirrus outflow clouds from the upper portion of the thunderstorm reflecting light from the setting sun. The timing of the storm was right around the time of sunset, and with the sun near or below the horizon, it's light is turned yellow, orange or red somewhat due to the blue end of the spectrum being scattered out be air molecules (sunlight passes through a lot more air when the sun is near the horizon than when it is high in the sky). When this warmly colored light illuminates the base of those thunderstorm anvil clouds, it produces the slightly eerie coloration that you reported.
Mar. 22, 2017 | Tags: atmospheric optics, thunderstorms

Question: There seems to be general dissatisfaction with the twice-yearly time changes -- serving little or no purpose for energy savings and being disruptive to people. Who or what body has the power to discontinue the national time changes? — Robert Weickert

Answer: Under existing national legislation, the dates of time change are set for the country as a whole, but individual states do have the option to draft legislation that opts the state out of switching to DST. Currently, Hawaii and Arizona do not switch to daylight time, and remain on standard time year-round. In that sense, the most direct means for you to lobby in favor of not changing the clocks twice a year would be to contact your state representatives and or state senators and ask them to push for legislation opting NC out of DST. Alternatively, you could make the same suggestions to your congressman or U.S. senators in hopes that they will push for changes to the national time legislation. The problem that seems to arise in switching to a single year-round time is that some people would rather that be standard time, while others would prefer DST, and a legislative stalemate ensues. There have also been suggestions to simply abandon time zones and have everyone switch to using Universal Time (meteorologists use this for weather observations, satellite data times, radiosonde balloon launches, computer model times, etc in order to maintain worldwide coordination), which has the advantage of 1030 or 1345 hours, for example, referring to the same moment in time whether you happen to be in Raleigh, Denver, London or anyplace worldwide.
Mar. 21, 2017 | Tags: maps & codes

Question: How do wind gusts (of 40 mph) impact flights? — Monique May

Answer: Flights are affected by gusty winds to varying degrees and in different ways depending on the phase of flight, the size and type of aircraft and in some cases the direction of the winds. When aircraft are in steady flight at fairly low altitudes, strong gusty winds can lead to a bumpy ride due to the turbulence involved, which causes sharp upward and downward motions in addition to the rapid increases and decreases in horizontal wind speed. Gusty winds can be more of an issue when an aircraft is in takeoff or landing mode. If the winds are blowing along the direction of the runway, sudden surges or lulls in wind speed can cause sudden changes in the effective airspeed of the plane, causing lift to be suddenly gained or lost (potentially leading to stalls), and there are techniques pilots can use to anticipate and partially offset these effects (such as adding part of the difference between steady winds and gust speeds to the approach or takeoff speed that they use). If the wind direction is largely perpendicular to the runway, strong gusts can cause sudden variations in the crosswind speed, making it difficult to remain properly lined up for takeoff or landing. Winds gusting beyond the crosswind limits of the aircraft can lead to aborted landings and go-arounds, and if they are persistent enough, can force the pilots to choose to proceed to an alternate airport where winds are lighter or are more favorably aligned with the runway.
Mar. 20, 2017 | Tags: weather & health, winds

Questions 1 - 10 of 5250.


Ask Greg Your Question Now!

Please understand that the volume of Ask Greg questions makes it impossible to answer every one or to list them all here. You may find it helpful to search for your own question using the form at the top of this page to see if it has been posted in our database.

When you submit a question you understand that your question and e-mail address will be sent to our editorial staff. Accordingly your question will not be subject to the privacy policy of this site.