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Recent Questions

Question: How is ambient temperature measured? Is it in the sun or in the shade? Since both influence the thermometer, how do we know the temperature? — Chuck

Answer: Ideally, the "surface" temperature is measured about 2 meters off the ground, in an open area with a grassy surface, well away from trees or buildings. The sensor should be in an area that isn't shaded, but the thermometer itself is housed in a light-colored ventilated enclosure so that it isn't exposed to direct sunlight in the daytime or to open sky at night. This allows the thermometer to measure the temperature of the air passing through the enclosure itself, without reading too high in the daytime because of solar energy being directly absorbed by the sensor, or too low at night because of infrared radiation leaving the sensor and causing it to become cooler than the surrounding air. Some official thermometer installations are "aspirated," meaning there is a fan that ensures outside air continually flows into and through the enclosure, even when ambient winds are calm or very light.
Aug. 7, 2016 | Tags: general meteorology, instruments

Question: Humidity is so important to how one feels in high heat. And high humidity with high heat can certainly cause health issues. Why is humidity not listed more prominently on the website (forecasts, current conditions, etc?) We get the temp and possibility of rain... why no humidity? — Greg Schneck

Answer: We agree that humidity levels play an important role in comfort, and potentially health and safety, when temperatures are on the hot side. For that reason, the write-ups in our seven day forecast will often mention humidity and/or expected heat index levels when those are of special interest. In addition, we certainly don't try to make it hard to find current and projected humidity values (and especially dew point, since that value is more directly proportional to how much moisture is in the air than is relative humidity). You'll find both of those displayed rather prominently when you click on our "Current Conditions" link, and likewise, if you click on the "Hourly" link you'll have access to a lot of info on humidity. First, there is a graph toward the bottom of the page that includes selections for humidity, dew point and "feels like" which is set to show heat index in hot weather, and wind chill when it's cold. Finally, in the hourly forecast, you'll see a "more details" link - clicking that link will show you projected dew point and relative humidity values every hour, along with the sky condition, rain chance, wind, etc.
Aug. 6, 2016 | Tags: humidity/dew point, weather & health,

Question: I saw a local grocery store has their bee hive exposed to full sun in this hot weather. Should not they move the bee hive to shaded area? I Am afraid bees may suffer or die since the temperature of the hive could be extremely high. — Y C Lee

Answer: That was a good thought to bring up, given the run of mid 90s temperatures and high humidity we were having when you wrote in. We did some checking on recommendations regarding hives and exposure to direct sun, and the general consensus was that bees are probably safe and will remain healthy despite direct sun and hot temperatures, though they may tend to expend more energy cooling the hive and thus be less productive in other ways during the hottest part of the day. Some beekeepers seem to favor, where possible, siting their hives in locations that will receive direct sunlight early in the day (prompting the bees to become active earlier) and will be shaded during the afternoon (allowing them to expend less effort cooling the hive, and leaving more energy for active foraging and honey production).
Aug. 5, 2016 | Tags: heat, weather & health

Question: What was the high temperature on July 28 officially at the RDU airport and in Clayton, plus what were the heat indices? — Deb Jones

Answer: Observations from Thursday July 28, 2016 from RDU show a maximum temperature of 96 degrees, with a top heat index value of 109. We also checked data from two stations in Clayton for that day, and found the respective highs were 98 and 97, with maximum heat index values of 106 and 104.
Aug. 4, 2016 | Tags: apparent temperature, heat, past weather

Question: In terms of circulation size or cloud canopy which one of these storms was the biggest.. Sandy or Super Typhoon Tip? — David

Answer: We weren't able to find comparable measurements of cloud area, but both systems were tracked with regard to the diameter of tropical storm force winds. While Sandy set the Atlantic record in that respect, with a circulation diameter of roughly 1000 miles, Typhoon Tip retains the global record by that measure, with a diameter of about 1350 miles. Until 2015, Tip was also known for the strongest maximum sustained winds in a tropical cyclone, at 190 mph. However, it was surpassed by eastern Pacific Hurricane Patricia's 215 mph peak sustained winds that season.
Aug. 3, 2016 | Tags: hurricanes, records/extremes

Question: In Holly Springs on Tuesday evening July 26th at 8:35 PM, we'd had rain, thunder and lightning, including one that sounded like a local strike for about half an hour with no warnings. Now that the power has gone off and on we are getting the notices online but not on the phone. Any idea why? I trust your team implicitly for weather notifications and warnings but this one seems to have slipped through the cracks. — Doris E Bornkessel

Answer: We reviewed radar and warning archives from that evening, and found that based on the time you sent your message and the location outlines of the warnings that were issued for the slow-moving storm that was drifting across the area then. We found that an initial severe thunderstorm warning was issued for western Wake County at 8:06 PM, but the boundary of that warning was just northwest of Holly Springs. As the storm spread a little more intensely east and southeast, an updated, expanded warning area was issued at 8:45 PM. That one did included Holly Springs. While the storm produced a terrific amount of lightning, some rainfall totals on the order of 1-2 inches and gusty winds, reported damage was limited to trees down in a couple of isolated locations.
Aug. 2, 2016 | Tags: past weather, severe weather,

Question: How long is this excessive heatwave (temps above 95) going to be in NC? — Brandon

Answer: You sent your question midway through the stretch of above-normal heat, and at the time we are writing this answer, it appears the heat will begin to abate, at least temporarily, by the time you read it. While it will remain seasonably warm and humid, the mid and upper 90s highs should be running more on the order of mid 80s to low 90s as we kick off August, perhaps edging back up somewhat late in the week. This is a very general outlook from a few days before the answer posts on our web site, so we'd refer you to the current 7-day forecast for the latest information.
Aug. 1, 2016 | Tags: heat,

Question: We have a home on Cameron Hill Rd in Cameron, and the storms that hit last Friday cut a path of destruction at our house and the surrounding area that looks like a tornado hit here, but I did not get a tornado warning. Was there a tornado? — April

Answer: A cluster of thunderstorms late that afternoon and early evening cycles rapidly through development and dissipation over parts of Moore, Chatham, Lee, Harnett, Cumberland and Hoke counties. While they did not produce any tornadoes, they did generate some downdraft/outflow winds that were strong enough to cause pockets of damage. There were three severe thunderstorm warnings issued by the NWS in association with these cells, the first two covering parts of Chatham and Lee counties, and the final one covering the southeastern corner of Moore, along with parts of Hoke, Cumberland and Harnett counties. It appears a few damaging wind gusts did extend outside the boundaries of the warning area over eastern Moore County, and that the northwestern corner of the warning area was just a little south of your location, leaving you out of the warnings that were issued.
Jul. 31, 2016 | Tags: past weather, severe weather

Question: Why is lightning often associated with volcanic eruptions? I visited Kyushu two years ago and saw the Sakurajima volcano then. In online photos of eruptions since then they often had lightning within the smoke plume. — Charlie Smith

Answer: Many volcanoes that generate large ash and/or condensed steam clouds during energetic eruptions likewise produce an array of lightning discharges, some very similar to thunderstorms and others in the form of very small discharges that may only travel a few feet. The precise mechanisms of charge separation that produce lightning in any form remain poorly understood, but the general idea is that particles (in the case of volcanoes, pulverized bits of glass, minerals and rocks, sometimes together with water droplets and ice particles formed from a combination of water vapor released from the volcano itself or from lakes, snow cover or glaciers on or around it) that are violently and turbulently lifted into the air can become electrically charged by transferring electrons from one to another so that a surfeit or deficit develops in individual particles. Then, a separation process occurs that concentrates particles having negative charges in some layers or pockets of the cloud and results in other pockets or layers favoring positive charges.

When the difference in charge becomes great enough between a positive area and a negative one, the insulating properties of air are overcome and a "spark" occurs, carrying current from one point to the other, often within the cloud but sometimes to an oppositely charged point on the ground (the earth's surface is, on average, negatively charged, but positively charged "shadow areas" on the surface can form underneath strong negative charge centers in the lower levels of clouds).

As you noted in your message to us, there is a nice photo of a bolt from the Sakurajima cloud in an article at
Jul. 30, 2016 | Tags: cool sites, lightning, volcanoes

Question: I'm curious about the LOWEST dewpoint ever recorded for this area? — James

Answer: The lowest dew point ever observed at the RDU airport was a very dry -28 degrees Fahrenheit on Jan 21, 1985, while for comparison purposes the highest was a steamy 82 on Aug 10, 2007. Those numbers are known to us thanks to a special search of hourly observations carried out by the State Climate Office to identify a few of the highest and lowest hourly dew point readings in the airport database.
Jul. 29, 2016 | Tags: humidity/dew point, records/extremes

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