Ask the Meteorologists

Recent Questions

Question: The Nov 28th aviation reports had wind from the northwest and gusty. What constitutes a gust? — Chris

Answer: Reported gusts are defined as the highest instantaneous wind speed when there are rapid fluctuations in wind speed and there is at least a 10 knot difference between peaks and lulls. This definition is spelled out in Federal Meteorological Handbook 1 (FMH-1), "Surface Weather Observations and Reports." The term "gusty winds" would imply that winds are sufficiently variable to produce those rapid 10 knot or greater fluctuations.
Dec. 7, 2018 | Tags: maps & codes, winds

Question: Is cocorahs the best amateur group? Thanks for any advice. — R. Koch

Answer: If you're interested in a rather continuous commitment to making weather observations that contribute to detailed analyses of precipitation patterns around the country, you might find that to be an excellent group to participate in. The Community Collaborative Rain Hail and Snow network (CoCoRaHS) web site has all the details you need to know about the reason it was initiated and how it operates, in addition to advice on making accurate precipitation observations - for more information, see www.cocorahs.org. Note that even if you have an automated home weather station rain gauge, CoCoRaHS requests that you obtain a 4-inch diameter manual rain gauge which is considered more accurate and enhances the consistency of observations across the network.
Dec. 6, 2018 | Tags: cool sites, hail, instruments, rain, snow

Question: What is a good weather station for home use? — Reinhard Koch

Answer: There are a number of reputable companies (Davis, La Crosse, Rainwise, Acurite, Oregon Scientific, etc) that make complete home weather stations that range from quite basic to very advanced (and from inexpensive to rather costly as you move up the quality/accuracy/convenience scale), to include wired or wireless installations and data transfer. Most include software for archiving and displaying the data on a PC, tablet or laptop, and some can upload observations to the Weather Underground or other web services where you can monitor it remotely when you're not at home. You can find a number of suppliers for these systems by doing a web search for the phrase "home weather station," and most of the sites include customer reviews that may help you decide on the system that best fits your purposes. We would recommend going with one that falls in the "complete" category, so that it includes instruments to measure wind and precipitation, but we don't have a specific brand or model that we endorse.
Dec. 5, 2018 | Tags: instruments

Question: I am driving from Cary to New Baltimore, MI and I am looking for an app or website I can use during my travels to stay on top of the weather especially with the mountains and snow. — Mary Kay

Answer: We would note, of course, that our WRAL Weather App is not restricted to use in our local area, but can detect your location and display current and forecast information anywhere you happen to be, along with any warnings that might be issued for that location. However, there are a couple of recent apps that are designed to plan ahead by showing expected weather conditions along the route of a trip based on entered starting and destination locations. Two of those are called Weather on Wheels, and Weather Route, and you may be able to find others by searching the iOS or Google Play stores online. In addition, of course, weather.gov is a National Weather Service web site that offers up forecasts and watch/warning information nationwide.
Dec. 4, 2018 | Tags: cool sites, wral.com

Question: I've heard from one almanac that we're going to have a cold winter with plenty of snow, then another states the opposite. I was just wondering, which do you think it will be? Myself, I'm hoping for the snow. — Mallory Anderson

Answer: In the "O'Fishel Winter Forecast," we settled on 5-8 inches as an amount to call for in the Raleigh area for the winter, but we do acknowledge and point out that seasonal snow amounts are highly variable due to how sensitive those totals are to just one or two storm systems that are especially productive or a couple of potentially strong systems that turn out to produce mostly rain or slush instead. These kinds of details can't be forecast more than a few days instead. Rather, it is possible to forecast with somewhat more success the occurrence of large scale patterns like El Nino or La Nina, and how they may combine with other influences to tilt our odds of precipitation toward higher or lower than normal amounts (this year, higher than normal amounts are somewhat more likely than near-normal or below normal), or tilt our odds of temperatures, although this year that is an especially hard call, and there's a nearly equal chance we could be above, below or near normal for the season. The amount of snow over the winter season does correlate somewhat with temperature, so that warmer years tend to have less snow and vice versa, but it is a fairly weak correlation with a lot of scatter. There is an even weaker correlation between an index that describes the state and strength of El Nino and how much snow falls during the winter season.
Dec. 3, 2018 | Tags: el nino/la nina, snow, winter weather

Question: We are coming up on the 30th anniversary of the tornado that came through the Raleigh area around 1 a.m. November 28. I recall that on the 11 p.m. broadcast evening Greg said something like "it is 77 degrees at 11 p.m. in late-November". The other recollection I have is that the winds were really strong all day long. Do you have any records that show how strong the winds were that day and would the persistent winds be a sign of potential danger. Would the unseasonable temperatures also be a red flag? — Dave Crotts

Answer: We have indeed recently passed that anniversary, and the tornado produced that night, one of 7 that occurred around eastern NC and southeastern VA in the outbreak, was one of the strongest and longest-lived in NC history. It was rated F4 on the Fujita scale in use at the time, tracked along a path 84 miles long over about 2 hours, and unfortunately took four lives and left 1000 people homeless. You might be surprised to know that in the day leading up to the storm, surface winds were about 5-10 mph through much of the day, becoming south to southwest about 10-15 mph through the later evening (winds were a little stronger east of Raleigh through the day, around 10-20 mph). Certainly the unusual warmth played a role in making the atmosphere unstable enough for tornadoes, as did the unseasonably humid air through the lower and middle atmosphere. there was also moderately strong vertical wind shear, both in terms of speed and direction, which contributed, and there are also papers that link the intensity of the system to gravity waves that propagated into the region from other disturbance to our southwest. The temperature in Raleigh at 11 PM was around 71 degrees, but was rising a bit at that time from upper 60s after a high of 75 earlier in the day. There were some high temperatures in the upper 70s southeast of Raleigh. To some extent, those are both red flags, but it's worth noting that we have plenty of unseasonably warm and humid episodes over the years that do not yield severe thunderstorms or intense tornadoes. There's a summary of the event from the Raleigh NWS office available at www4.ncsu.edu/~nwsfo/storage/cases/19881128/.
Dec. 2, 2018 | Tags: cool sites, past weather, severe weather, tornadoes

Question: You mentioned you would be heading up North for the Thanksgiving holiday 2018: is that PA or NYC? — Phillip Walden

Answer: It was to New York City this time around, where Thanksgiving was tied for second coldest ever, and coldest since 1901 according to records for the Central Park area. It was breezy, but not as windy as had been expected at one time, which allowed the Macy's parade folks to fly their famous balloons, albeit a little lower than they typically do.
Dec. 1, 2018 | Tags: cold, records/extremes, weather & health

Question: I was looking at the Doppler radar Saturday morning. I don't think I have seen it lit up like that for such a large area. I saw the yellow and red and know what that was. I also saw some areas of black up by the Virginia border. What would that be? — Mike Andrews

Answer: That would have been the morning of November 24th, and while we did have areas of rain crossing the region then, the radar images you saw on one part of our web site (the view labeled "DUALDOPPLER5000") was showing incorrect reflectivity values that were much more intense than the actual retrns measured by the radar. This led areas that should have been green showing as red, yellows as purple, reds as black, etc. The reflectivities on our display that would be shown in black are extremely high, typically seen only in thunderstorms with very large hail. On Saturday, the radar itself was actually working properly and providing valid data, but a problem translating that data to graphics by a company we use to populate those maps caused the temporarily "hot" appearance. If you happen to see that kind of thing again, one thing to do is check some of the other locations with radar data on our site. For example, you can see a live sweeping view from the same radar by clicking the "Live Stream" link below the main image, and you can also use the iControl radar display, using the selector above the image to change the view from "National" to "DualDoppler 5000." In both cases, the radar data looked correct from those sources on our web site Saturday morning. Another option is to check one of our regional or national composite radar views.
Nov. 30, 2018 | Tags: weather radar, wral.com

Question: How many days has it rained in Raleigh in 2018? — Nikki Heron

Answer: When we drafted an answer to your question, we had data up through November 23rd. At that time, measurable rain (.01" or more) had been recorded at the RDU airport on 122 days. For the same portion of the year, observations for Raleigh going back to 1887 show that 1943 had the fewest days, at 77, while 1989 had the most at 140. The 122 this year for that stretch of time was the 9th most on record, although due to some ties between other years, there have been 15 years since 1887 with more days of measurable rain.
Nov. 29, 2018 | Tags: past weather, rain, records/extremes

Question: Why are we getting a constant barrage of "Warnings" for flooding in Durham and Chatham Counties when there hasn't been any rain for days? There won't be any for days AND Jordan lake is 10 feet lower than "full." I don't get it. — Morgan Feldman

Answer: The weather service issued small stream flood warnings for the area around New Hope Creek, which was out of its banks and flooding roads in southeastern Durham and northeastern Chatham counties in the days leading up to your question. The warnings were discontinued when the water levels fell enough to allow the roads to dry and be opened. In addition, on the day you sent your message, the Jordan Lake level was 231.1 feet. This is 15.1 feet above the guide curve, or "full pool," for that lake. It was a little under 9 feet below the "flood pool" level of 240 feet, but still represents an unusually high level (only a foot or so below the peak reached in the wake of Florence) that probably contributed to the flooding of some of the immediately adjacent creeks.
Nov. 28, 2018 | Tags: flooding, lakes and rivers

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