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Answer: According to a climatology of severe weather for central NC produced by our local NWS office, the Raleigh county warning area (covering 31 counties) averages about 5 tornadoes per year. Comparing tornado rates for different parts of the country requires balancing the area involved in the estimates, and a few different methods have been applied in various studies and technical reports. For example, a method estimating the number of tornadoes occurring within 25 nautical miles of any given point shows a value of .4-.8 per year for central NC versus about 1.0-1.4 per year over central OK in the heart of "tornado alley." A similar statistic for F2 and stronger tornadoes shows about 5-15 per century for our state versus about 35-40 there. Another estimate of the fraction of land surface disturbed by tornadoes each year in NC is about 2.1 x 10^-4, compared to around 4.4 to 4.8 x 10^-4 in the most active regions of the country. Finally, an analysis of tornadoes from 1950-2003 that counted tornado events within 2-degree latitude by 2-deg longitude boxes across the U.S. showed 303 in a box including our area, while boxes in the central plains states ranged from around 700 to as high as 942. Taken all together, then, we see that the "tornado alley" areas have about 2-3 times as many tornadoes over a given area as we do overall, but if you exclude the weak F0 and F1 tornadoes and look in particular at the more powerful F2 intensity and higher storms, those are about 4-5 times more likely in states like Oklahoma than they are around here.
Oct. 29, 2009 | Tags: normals, severe weather, tornadoes

Answer: The center of Hurricane Hugo sped into North Carolina the morning of September 22, 1989 after crossing the South Carolina coastline around Charleston the evening before. You can see details of its track by selecting it from the "Major NC Storms" box on our interactive hurricane tracker in the "hurricanes" section of our web site. The devastating tornado that reached F4 intensity, destroyed the northwest Raleigh K-Mart, and killed 2 people each in Wake and Nash counties, touched down around 1 am on November 28, 1988 in Umstead State Park and then followed an 84-mile path toward the northeast that ended near Jackson in Northampton County. As the dates illustrate, these two systems were not related. You can see much more about the Raleigh tornado in a National Weather Service event summary at www4.ncsu.edu/~nwsfo/storage/cases/19881128/.
Oct. 13, 2009 | Tags: cool sites, hurricanes, past weather, tornadoes

Answer: You probably noted in the class that most significant tornadoes form on the right rear flank of supercell thunderstorms, relative to the direction of storm movement. If the supercell is a "discrete" storm, out on its own, then most of the rain, thunder and lightning would be over when the tornado moves through or very shortly afterward. However, sometimes the tornadic supercell can be just one part of a larger group or line of thunderstorms, in which case additional areas of rain, lightning and perhaps hail may pass across the same area. In rare cases, there can even be multiple tornadic cells that cross the same or nearly the same location.
Sep. 17, 2009 | Tags: severe weather, thunderstorms, tornadoes

Answer: The idea behind finding a ditch or other significant terrain depression to take cover in is not that it is necessarily guaranteed to be safe, but that lacking any better alternatives, it is greatly preferable to being fully exposed to the intense winds of the tornado and especially to any debris (wood, glass, metal and so on) being carried at high speed by those winds. The hope is that the debris and the strongest wind will pass over your head if you can find a suitable spot to shelter in.
Sep. 11, 2009 | Tags: preparedness, tornadoes

Answer: Tornadoes certainly do occur in both those areas, but geographic factors lead to a much lower prevalence there than in parts of the United States. For example, a French study of significant (F2 and stronger) tornadoes there identified 58 between 1960 and 1988, and established that the frequency of such tornadoes was about 1/15th that of the U.S. Great Plains region. Notable tornadoes have been reported in most other European countries as well. It's likely we don't hear about more of them because they are both infrequent and often deemed of primarily local rather than international news value.
Aug. 28, 2009 | Tags: tornadoes

Answer: Ideally, if you can clearly determine the direction of movement of the tornado and there is a route that will take you at a right angle to its motion, that will be most effective in moving you out of the storm's path. Most tornado safety references do not advise trying to outrun the tornado by driving away from it in the same direction that it is headed. You can read more about tornado/automobile safety at www.spc.noaa.gov/faq/tornado/#Safety.
Aug. 12, 2009 | Tags: preparedness, tornadoes

Answer: A check of local storm reports compiled by NOAA's Storm Prediction Center for that date, along with local news stories, shows that straight-line winds associated with a severe thunderstorm was the most likely reason for a number of trees that were toppled in the vicinity of Red Mountain Road around 2 pm. There were two tornado reports in the state that day, near Pinetown and Washington, both in Beaufort County. You can see storm reports for that day at www.spc.noaa.gov/climo/reports/090717_rpts.html, and can also scroll to the bottom of the page to select another date.
Aug. 7, 2009 | Tags: cool sites, past weather, severe weather, tornadoes

Answer: All safety rules of thumb are subject to variations arising from unique circumstances, but even with a natural gas furnace in a basement, it is likely among the safest locations available should a home be struck directly by a strong or violent tornado. If active gas lines are damaged by the tornado, there is at least some risk of fire or explosion, but it is worth noting that unlike propane, for example, natural gas vapor is lighter than air and will tend to disperse rather than collecting in low spots. Of course, if you smell gas in the wake of tornado damage, avoid lighting matches or creating sparks, evacuate the property and contact 911 or your gas provider. You can find a good collection of tornado safety advice at www.spc.noaa.gov/faq/tornado/safety.html.
Aug. 6, 2009 | Tags: preparedness, tornadoes

Answer: According to a severe weather climatology for central North Carolina compiled by the Raleigh National Weather Service office, about 43 percent of our tornadoes form in the spring, 26 percent during summer and 23 percent in the fall, with the greatest percentage occurring between March and June. Over half of the tornadoes in our area form during the later afternoon and early evening, between the hours of 3 and 8 pm.
Jul. 30, 2009 | Tags: normals, tornadoes

Answer: Yes they can. The most recent tornado reported in San Jose was an F0 twister that occurred in December 1997. It covered a path length of less than a mile with a width around 100 yards, and produced around $20,000 in damage to some mobile homes. There have been at least five other tornadoes in surrounding Santa Clara county since 1950, two of which produced F2-level damage.
Jul. 2, 2009 | Tags: tornadoes