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Question: I'm looking at the sky tonight and I am seeing one of the biggest and most beautiful stars. It is so bright, I can see points all around it. Is this unusual or do I not look up in the sky enough because I have never seen a star this close to earth? — Candice L.

Answer: You noted that the time you saw this was around 8:30 PM on January 26th. We think it is almost certain that you were noticing the planet Venus, which is currently in it's "Evening Star" position well to one side of the sun, so that it is visible at nearly its highest angle of the year above the horizon in the hours after sunset. As long as clouds don't interfere, you can see it night after night for a good while yet in the western sky, and gives exactly that sense of being VERY bright and "close." One that that you might notice on close inspection is that it is a very steady light, whereas even bright stars tend to "twinkle," with their brightness and precise position fluctuating just a bit. That difference is a common way to discern the much closer planets in our sky from the vastly more distant stars.
Feb. 5, 2017 | Tags: astronomy, atmospheric optics

Question: I was at your WRAL exhibit at the NC Museum of Natural Science, and I really liked it! I did the "forecast" thing, but, I do have one question about it: how do you forecast the wind direction? How do you predict that? Because I just couldn't figure out how to get that one right! I really liked your exhibit though; it was really cool! — Daniel

Answer: We're really glad you enjoyed the exhibit! Forecasting wind direction in most cases comes down to utilizing forecasts from computer models of what the surface pressure pattern is expected to be an how it will change over time, along with understanding some quirks and details of how those patterns relate to the likely direction of flow. The basic relationship we look for is that wind flows clockwise and outward around high pressure centers and vice versa for lows (in the northern hemisphere). We usually visualize the pressure patterns with "isobars" or lines of equal pressure. Where these lines run parallel to each other, the wind flows in a direction such that lower pressure is on the left and vice versa, with about a 30-45 degree angle toward low pressure (over land) and more like a 10-20 degree angle toward low pressure over water. The speed of the wind is inversely proportional to the distance between isobars, so that closer spacing equates to higher speeds and vice versa. For more detailed forecasts, and to help us further quantify expected speeds and gust levels, we use tools that compute and display wind vectors from various computer models in vertical profile graphically (one tool for this is called BUFKIT), and some products that use statistical correlations of computer output in the past to the actual observed winds that resulted. These are called MOS products (Model Output Statistics) and they provide numerical estimates of wind direction and speed every three hours for selected locations.
Feb. 4, 2017 | Tags: maps & codes, winds

Question: I got a weather surprise today (January 26) around noon as I was bike riding West on Hillsborough Street near NCSU. I was going to try to experience the passage of the strong cold front that I had been tracking over time on the personal weather stations to the West of us. As the front got to somewhere between Cary and West Raleigh a narrow line of heavy rain and wind similar to a squall line suddenly blew up within roughly a 5-minute period. From looking at myfox8 interactive radar website when I got home it seemed to have blown up around I-540. A lot of times this sudden development happens with summer thunderstorms between Durham and Raleigh or around I-95 well to the East. Can you explain the dynamics of this type of pop-up squall line? — Dave Crotts

Answer: The frontal structure that day appears to have been of the "split front" variety in which a cold front aloft decouples from and surges well ahead of a lagging surface cold front. In these situations, there is usually a band of fairly widespread precipitation that is located along a "warm conveyor belt" of moist air that is acted on in part by upward motions associated with a broad upper-level trough following along behind both frontal boundaries. That band of precipitation is what occurred through the late night/early morning hours on Thursday. The cold front aloft brought a deep layer of cooler, drier air into place that caused some clearing in the wake of the morning rain, but left a fairly moist, shallow layer of warmer air near the surface along and ahead of the surface cold front. By the time that front moved in to the Raleigh area, the break in cloud cover had allowed significant warming at the surface, leading to substantial instability due to the warm surface and cooling airmass aloft. At about the same time, the surface front provided some measure of lift to the low-level air along it (due to drier, cooler, and thus more dense air undercutting the warmer, more humid air) and at about the same time a concentration of higher winds aloft (a subtle jet streak) moved into position to also provide a measure of enhanced upward motion. Where the two features overlapped, we saw a northeast to southwest oriented line of showers develop, and they briefly become rather intense over a small area. In short order, the surface front moved on to the east, the jet streak pulled away northeast, and skies cleared again. You can read briefly about split fronts and see a couple of helpful diagrams at www4.ncsu.edu/~nwsfo/storage/training/jets/split.html.
Feb. 3, 2017 | Tags: cool sites, fronts & airmasses, past weather

Question: When was the last hail event that occurred in the Piedmont Area? — Deborah L Trogdon

Answer: The last event we could find with several hail reports around the Piedmont was on Sep 30, 2016. Most of the hail was in the dime to nickel size category, not quite reaching the severe weather criteria of 1 inch diameter (quarter size) or greater. There was a more sizable outbreak that included some severe-level hail reports, though, two days earlier on Sep 28th. You can see a map and listing of the reports for that day at www.spc.noaa.gov/climo/reports/160928_rpts.html, and there are links above the map that let you step forward or backward by one day.
Feb. 2, 2017 | Tags: cool sites, hail

Question: I'm going into high school this year and I was wondering what classes I need to take to be a meteorologist. Are there any specific classes I need to take? — Luke

Answer: If you're planning to pursue a meteorology degree in college, you would do well at the high school level to take courses in mathematics (the most advanced available at your school), physics, chemistry, statistics if they offer it, and computer science. To supplement these nicely, courses in geography and geology, if offered, along with writing and public speaking classes, would be very beneficial. Good luck!
Feb. 1, 2017 | Tags: careers & education

Question: Do you have any suggestion for an app for my laptop to watch the sky? — Tony White

Answer: We certainly haven't tried all the products and programs that might be available, but for visualizing the night sky as seen from a selected location on any given date or time, we've had good luck with one called AstroViewer, and we'd also note that the visuals you see in the Carolina Skies segments we do on Saturday mornings in collaboration with the Morehead Planetarium and Science Center are made with software called Stellarium. It's in a different vein, but you might also enjoy a program from the Jet Propulsion Laboratory called "NASA's Eyes." All of these and more should turn up in a web search by name, or more generally searching for "planetarium software."
Jan. 31, 2017 | Tags: astronomy

Question: Can you please explain what dew point is so an ordinary person can understand it? — Lynda

Answer: Sure thing! Dew point is a measure of how much invisible water vapor is in the air, so that the higher the dew point, the more water vapor and vice versa. Dew point is expressed as a temperature, and if the actual temperature of the air becomes equal to the dew point, the air is considered saturated with water vapor so that any additional cooling of the air or increase in water vapor will result in condensation, or a change of the water vapor molecules into liquid water. This can lead to the formation of cloud or fog droplets in the air and, when conditions are appropriate, the development of precipitation. Another common illustration of this is when you see "sweat" form on the outside of an iced beverage. If or when the outside of the glass cools down to the dew point of the air surrounding it or below, water vapor in contact with the glass will condense onto its surface.
Jan. 30, 2017 | Tags: general meteorology, humidity/dew point

Question: I know its very early but we want to have a Patriots Superbowl party and turn on the projector in the garage, but if it is going to be freezing it will change the plans. Any idea if the current warmth will continue 13 days from now? — Tim Urdi

Answer: Long range projections that far in advance have been giving mixed signals by then. After a return to typical winter temperatures late last week, it appears we'll vary a little above and below normal in the week ahead. Early indications from ensemble systems extending to that Sunday center around lows below freezing and highs potentially in the 40s, but they also indicate a large spread in solutions and therefore pretty low confidence about that period. We have to suggest keeping your plans flexible for now, and then following more specific forecasts for that day that we will be making as we move through the second half or so of the week.
Jan. 29, 2017 | Tags: general meteorology, wral.com

Question: Can it snow at temperatures above freezing? I've heard that some of the most powerful snowstorms dropped snow at temperatures around 36 degrees. Is this true? — Luke

Answer: It can certainly snow at surface temperatures well above freezing, although there has to be air above in the region where the snowflakes form that is well below freezing. While it is fairly unusual for snow to fall with surface temperatures warmer than the 30s, on rare occasion snow has been observed at the surface with temperatures, at least briefly, in the mid 40s. This can happen when a pocket of very cold air a few thousand feet up moves across an area in the presence of moderate amounts of low level humidity and warm ground (creating significant instability that can touch off showers or snow showers), and usually involves variable cloud cover that allows some sun to reach the surface. This results in a rapid decrease in temperature with height, so that snow from above only has to fall through a shallow layer of warm air that fails to melt it before it reaches the surface. We're not sure where the 36 degree reference comes from, but it is possible for heavy snow to fall at such a temperature, although if the snow continues at a heavy rate it would tend, through absorption of heat by melting, conduction and evaporation, to lower the temperature of the surrounding air. Conversely, if the above freezing temperature is reinforced by warmer air being advected into the region over a deeper layer, it would tend to eventually change the snow over to rain.
Jan. 28, 2017 | Tags: snow

Question: What is the longest period of continuous below 32 degree temperature to occur in the Raleigh or central NC region? I am curious if this past weekend is close to a record. — Ingrid Harm-Ernandes

Answer: You're asking about the weekend (Jan 7th and 8th) that snow and sleet fell across the area. We did have cold air persist in the wake of that system, enough that out at the RDU airport the temperature was at or below 32 degrees for 83 consecutive hours, finally climbing above freezing after 10 AM on Tuesday Jan 10th. That's only a little over half as long as the record for consecutive hourly reports of 32 or colder, though. With some assistance from the helpful staffs of the State Climate Office of NC and the Southeast Regional Climate Center, we found the longest such period for Raleigh went on for 157 hours (about 6 and a half days) ending on Jan 16th in 1982.
Jan. 27, 2017 | Tags: cold, records/extremes

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