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Question: This morning when checking the weather maps I noticed an odd-colored purple frontal boundary stretching from Winnepeg south through much of western Minnesota. Wikipedia tells me it is an occluded front, and being someone who watches the local news the majority of evenings, it struck me as odd that I'd never heard the term before. Is it that I've not been a good weather citizen all these years, or are they uncommon to see? How often do we encounter them in the Piedmont? — Matt in Durham
Answer: Occlusions are quite common overall as a part of the general organization of mid-latitude synoptic storm systems. In somewhat oversimplified terms, they arise where cold fronts catch up to warm fronts, such that the warmer airmass between those two boundaries is lifted off the ground in and along the vicinity of the occluded front. For much of the year, they tend to occur most frequently north or northwest of us, while more typical warm fronts, cold fronts and stationary fronts extending south of the primary low pressure areas affect us. However, during the winter months, we tend to see a few occluded fronts track across our state when surface low pressure systems follow a notably more southerly path than at other times of year. The character of weather associated with them falls somewhere between classic warm front and cold fronts, and can lean closer to either, depending on the distribution of temperature and moisture around a particular storm system. Now that you're aware of them, you'll likely notice them on weather maps rather often, in many cases running just east and/or southeast from slow-moving, deep low pressure centers.
Sep. 30, 2016 | Tags: fronts & airmasses, general meteorology
Question: Do you work in shifts? I've noticed Mike Moss in the background before even when it wasn't his day to report the weather. Is there staffing 24/7, or is the WeatherCenter only staffed during the graveyard shift when there is expected inclement weather? — Brian
Answer: As you noted, when significant weather scenarios involving wintry precipitation, hurricanes, severe weather outbreaks and the like are underway, we usually go to 24-hour staffing, often with two meteorologists on duty at all times. However, due to the near 24-hour cycle followed in news these days, on TV, radio, the internet and mobile platforms, our regular schedules do not fall all that much short of 24-hour coverage. There is usually at least one meteorologist on duty from around 2 or 3 in the morning until around midnight. A typical week will find Elizabeth Gardner paired with Mike Moss or Aimee Wilmoth during the early to mid morning, then Mike Maze and Greg Fishel through the mid-afternoon and evening hours, with Nate Johnson often working a mid-morning to late afternoon shift. On weekends, we usually have one person cover the early morning to midday, then another cover mid-afternoon to near midnight. Again, if the potential for threatening weather is in the forecast, we may augment the weekend staffing, or sometimes simply designate one or two people to be on call for a short-notice response to help out if needed.
Sep. 29, 2016 | Tags: careers & education, wral.com
Question: WRAL continually has higher daily forecasted temps. For instance, this week (Mon-Fri), you're approximately 3 degrees per day warmer than other sources. What causes this? Is your location a factor? I can't figure out why? — Dan
Answer: We suspect that if you kept track over a long period of time, there might not be so consistent a difference toward warmer or colder by a few degrees, but it has been the case that in the past few weeks we've had several scenarios in which we both felt the pattern that was developing was one that would lean toward higher than normal temperatures, and we had also noted that calculated temperature projections from a number of computer models (both in the way of "raw" output, and statistically adjusted forecasts that are intended to reduce biases) were frequently under-predicting highs by anywhere from around 2-5 degrees under some conditions. When we felt this was an applicable issue, we forecast temperatures that we felt were most likely to occur, and as you noted in a number of instances our numbers were on the high side of those you'd see elsewhere. Fortunately, at least during those few weeks, the higher numbers often proved to be verified by later observations.
Sep. 28, 2016 | Tags: heat, past weather
Question: Back in the late eighties/early 90's, in January, in Durham (presumably in the surrounding areas as well), we had a very hot day, at least in the 80's followed by a day where it snowed significantly (6 to 8 inches) that was not forecast to occur. What reference(s) would you recommend that I use to find data on this event? — Ruth
Answer: You could try to narrow down the possible winter storm events by using the Winter Storms Database feature of the State Climate Office web site, at climate.ncsu.edu/climate/winter_wx/database.php. After finding the event that you think most resembles the timing and character of the storm you recall, you can use the Almanac section of our web site, and it's "Get Historical Data" feature, to look up temperatures observed at the RDU airport or other nearby locations in the days leading up to the snow.
Sep. 27, 2016 | Tags: cool sites, past weather, snow
Question: Would you please recommend a good website where I could find local (Chapel Hill) weather information such as the high and low temperatures for a given day, number of days the high temperature reached 90 degrees, number of days the low temperature was below freezing, amount of rain on a given day, amount of rain for the year, etc.? — Richard Woeller
Answer: You can look a lot of that up using the "Almanac" section of our web site, which will link you to historical weather information for a selected date - it will default to RDU, but you can change locations from the resulting page, as well as change dates or choose to view data over daily, weekly or monthly time frames.
While there's a little bit of a learning curve, you can also run more sophisticated searches to find averages, or the number of times that thresholds were exceeded for defined periods of time, and many other statistics, using the database tools at xmacis.rcc-acis.org/. If you're really into delving deeply into this tool, there is a one hour user training video link at the bottom of the home page for the tool. There is also a short written tutorial we found online for a few key types of searches that might help you get familiar with the interface more quickly. It's located at www.srh.noaa.gov/images/ffc/climate/xmACIS2_guidance.pdf.
Sep. 26, 2016 | Tags: cool sites, past weather
Question: What is an areal flood? — Arr Schaller
Answer: It's probably easiest to describe by comparing it to the other common flood warnings that the National Weather Service may issue, since they differ largely in the sense of how quickly the onset of flooding may occur, and how localized flooding is expected to be. They define flash flood warnings and areal flood warnings in the following ways:
A Flash Flood Warning is issued for flooding that normally occurs within six hours of heavy or intense rainfall. This results in small creeks and streams quickly rising out of their banks. Dangerous flooding in areas near these creeks and streams, as well as low-lying flood prone areas, develops very quickly and is a significant threat to life and/or property.
An Areal Flood Warning is normally issued for flooding that develops more gradually, usually from prolonged and persistent moderate to heavy rainfall. This results in a gradual ponding or buildup of water in low-lying, flood prone areas, as well as small creeks and streams. The flooding normally occurs more than six hours after the rainfall begins, and may cover a large area. However, even though this type of flooding develops more slowly than flash flooding, it can still be a threat to life and property.
A third type to be aware of is the River Flood Warning, which is issued when runoff from extended periods or large areas of heavy precipitation cause rivers to reach or exceed established elevation levels that correspond to minor, moderate or major flooding levels at designated gauge locations along the river. While the other warnings typically remain in place for a few to several hours, river warnings can sometimes stay in effect for days.
Sep. 25, 2016 | Tags: flooding, preparedness, rain
Question: When are the earliest and latest dates Raleigh has seen 90 degrees? — Caravaggio
Answer: In records stretching back to 1887, the earliest occurrence of 90 or higher for Raleigh was on March 12, 1990, while the latest was on October 10, 1939. The average date of the first 90 or higher of the year is May 10th, while the average date of the last 90 or higher is September 11th.
Sep. 24, 2016 | Tags: heat, normals, records/extremes
Question: Can you tell me if there is a way to look up wind directions from past days? The specific day I was looking for was September 10th 2016. — Jonathan
Answer: To track wind direction over time, and see that data graphically, you can click the "Almanac" link on our web site, then enter your date under "Get Historical Data." The resulting page will default to data from the RDU airport, but does include a "Search for Another Location" box. Also, once you are on that page, you can change the view between daily, weekly and monthly, for example, and scroll down a bit to see graphs over that time span of several variables, wind speed and direction included. There are also links near the top of the page to step to the previous or next day, week or month, and you can see a table of text observations that include winds as well, by scrolling down past the graphical data.
Sep. 23, 2016 | Tags: past weather, winds, wral.com
Question: When do you think we will start seeing fall weather? (75 degrees or lower) — Heather West
Answer: We'll likely have a day or two here and there last weeks of September that stay in the upper 70s, but consistently seeing highs in the lower 70s or below could easily take until two or three weeks into October. We don't have any confident way to predict specific stretches of day-to-day weather that far in advance, but by that time frame we have reached a point where our normal high temperatures have declined into the low to mid 70s range.
Sep. 22, 2016 | Tags: normals
Question: Could we have a tornado in the fall season? — Amy
Answer: It can't be ruled out, as tornadoes are possible in any month of the year in our part of the state. Climatologically, they are most numerous in the Spring, during the period from March to May, with a small secondary peak in frequency in the September to November time frame. Fatalities from tornadoes are rather rare in our state overall, but it is notable that November has seen the third most tornado deaths, with 19 during the span from 1950 to 2014, behind the months of March (48) and April (38), as documented in a recent undergraduate student project carried out under the guidance of the Raleigh NWS office.
Sep. 21, 2016 | Tags: preparedness, tornadoes
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Published: 2007-10-09 14:40:00
Updated: 2014-06-24 16:06:51